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Chapter02.pdf

G
GLAMERDISGONZALEZ1

This document contains solutions to 11 problems involving the calculation of stresses, strains, elongations, and required dimensions for structural members under tensile loading. The problems apply concepts of stress, strain, modulus of elasticity, and relationships between load, area, elongation and stress to analyze steel, aluminum, nylon and other materials. Diameters, cross-sectional areas, elongations, moduli of elasticity and stresses are calculated for wires, rods, pipes and other structural elements. Safety factors and allowable stresses are also incorporated into the analyses.

Engineering
Related topics:
Mecánica de Materiales • Resistencia de Materiales • Ingeniería Civil • Ingeniería Mecánica • Ingeniería Industrial
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C CH HA AP PT TE ER R 2 2
Chapter02.pdf
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.1 An 80-m-long wire of 5-mm diameter is made of a steel with 200 GPa E = and an ultimate tensile strength of 400 MPa. If a factor of safety of 3.2 is desired, determine (a) the largest allowable tension in the wire, (b) the corresponding elongation of the wire. SOLUTION (a) 6 2 2 2 6 2 400 10 Pa (5) 19.635 mm 19.635 10 m 4 4 U A d π π σ − = × = = = = × 6 6 all (400 10 )(19.635 10 ) 7854 N 7854 2454 N . 3.2 U U U P A P P F S σ − = = × × = = = = all 2.45 kN = P  (b) 3 6 9 (2454)(80) 50.0 10 m (19.635 10 )(200 10 ) PL AE δ − − = = = × × × 50.0 mm δ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.2 A steel control rod is 5.5 ft long and must not stretch more than 0.04 in. when a 2-kip tensile load is applied to it. Knowing that 6 29 10 psi, E = × determine (a) the smallest diameter rod that should be used, (b) the corresponding normal stress caused by the load. SOLUTION (a) 6 (2000 lb)(5.5 12 in.) 0.04 in. (29 10 psi) : PL AE A δ × = = × 2 2 1 0.11379 in 4 π = = A d 0.38063 in. d = 0.381 in. d =  (b) 2 2000 lb 17580 psi 0.11379 in σ = = = P A 17.58 ksi σ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.3 Two gage marks are placed exactly 10 in. apart on a 1 2 -in.-diameter aluminum rod with 6 10.1 10 E = × psi and an ultimate strength of 16 ksi. Knowing that the distance between the gage marks is 10.009 in. after a load is applied, determine (a) the stress in the rod, (b) the factor of safety. SOLUTION (a) 10.009 10.000 0.009 in. δ = − = 6 3 (10.1 10 )(0.009) 9.09 10 psi 10 E L E L δ σ δ ε σ × = = = = = × 9.09 ksi σ =  (b) 16 . . 9.09 σ σ = = U F S . . 1.760 = F S 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.4 An 18-m-long steel wire of 5-mm diameter is to be used in the manufacture of a prestressed concrete beam. It is observed that the wire stretches 45 mm when a tensile force P is applied. Knowing that 200 GPa, E = determine (a) the magnitude of the force P, (b) the corresponding normal stress in the wire. SOLUTION (a) , or PL AE P AE L δ δ = = with 2 2 6 2 1 1 (0.005) 19.6350 10 m 4 4 A d π π − = = = × 6 2 9 2 (0.045 m)(19.6350 10 m )(200 10 N/m ) 9817.5 N 18 m P − × × = = 9.82 kN P =  (b) 6 6 2 9817.5 N 500 10 Pa 19.6350 10 m P A σ − = = = × × 500 MPa σ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.5 A polystyrene rod of length 12 in. and diameter 0.5 in. is subjected to an 800-lb tensile load. Knowing that E 6 0.45 10 psi, = × determine (a) the elongation of the rod, (b) the normal stress in the rod. SOLUTION 2 2 2 (0.5) 0.19635 in 4 4 π π = = = A d (a) 6 (800)(12) 0.1086 (0.19635)(0.45 10 ) PL AE δ = = = × 0.1086 in. δ =  (b) 800 4074 psi 0.19635 P A σ = = = 4.07 ksi σ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.6 A nylon thread is subjected to a 8.5-N tension force. Knowing that 3.3 GPa = E and that the length of the thread increases by 1.1%, determine (a) the diameter of the thread, (b) the stress in the thread. SOLUTION (a) Strain: 1.1 0.011 100 L δ ε = = = Stress: 9 6 (3.3 10 )(0.011) 36.3 10 Pa E σ ε = = × = × P A σ = Area: 9 2 6 8.5 234.16 10 m 36.3 10 P A σ − = = = × × Diameter: 9 6 4 (4)(234.16 10 ) 546 10 m A d π π − − × = = = × 0.546 mm d =  (b) Stress: 36.3 MPa σ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.7 Two gage marks are placed exactly 250 mm apart on a 12-mm-diameter aluminum rod. Knowing that, with an axial load of 6000 N acting on the rod, the distance between the gage marks is 250.18 mm, determine the modulus of elasticity of the aluminum used in the rod. SOLUTION 0 0 2 2 2 6 2 6 6 250.18 250.00 0.18 mm 0.18 mm 0.00072 250 mm (12) 113.097mm 113.097 10 m 4 4 6000 53.052 10 Pa 113.097 10 δ δ ε π π σ − − = Δ = − = − = = = = = = = = × = = = × × L L L L A d P A  6 9 53.052 10 73.683 10 Pa 0.00072 E σ ε × = = = × 73.7 GPa E = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.8 An aluminum pipe must not stretch more than 0.05 in. when it is subjected to a tensile load. Knowing that 6 10.1 10 E = × psi and that the maximum allowable normal stress is 14 ksi, determine (a) the maximum allowable length of the pipe, (b) the required area of the pipe if the tensile load is 127.5 kips. SOLUTION (a) ; PL AE δ = Thus, 6 3 (10.1 10 )(0.05) 14 10 EA E L P δ δ σ × = = = × 36.1 in. = L  (b) ; P A σ = Thus, 3 3 127.5 10 14 10 P A σ × = = × 2 9.11 in = A 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.9 An aluminum control rod must stretch 0.08 in. when a 500-lb tensile load is applied to it. Knowing that all 22 σ = ksi and 6 10.1 10 E = × psi, determine the smallest diameter and shortest length that can be selected for the rod. SOLUTION 3 all 2 all 3 all 2 500 lb, 0.08 in. 22 10 psi 500 0.022727 in 22 10 4 (4)(0.022727) 4 P P P A A A A d d δ σ σ σ σ π π π = = = × = < > = = × = = = min 0.1701 in. = d  all 6 3 all (10.1 10 )(0.08) 36.7 in. 22 10 E E L E L δ σ ε σ δ σ = = < × > = = × min 36.7 in. = L 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.10 A square yellow-brass bar must not stretch more than 2.5 mm when it is subjected to a tensile load. Knowing that 105 E = GPa and that the allowable tensile strength is 180 MPa, determine (a) the maximum allowable length of the bar, (b) the required dimensions of the cross section if the tensile load is 40 kN. SOLUTION 6 3 9 3 180 10 Pa 40 10 N 105 10 Pa 2.5 10 m P E σ δ − = × = × = × = × (a) 9 3 6 (105 10 )(2.5 10 ) 1.45833 m 180 10 PL L AE E E L σ δ δ σ − = = × × = = = × 1.458 m L =  (b) 3 6 2 2 6 40 10 222.22 10 m 222.22 mm 180 10 P A P A σ σ − = × = = = × = × 2 222.22 A a a A = = = 14.91 mm a = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.11 A 4-m-long steel rod must not stretch more than 3 mm and the normal stress must not exceed 150 MPa when the rod is subjected to a 10-kN axial load. Knowing that 200 GPa, E = determine the required diameter of the rod. SOLUTION 4 m L = 3 6 9 3 3 10 m, 150 10 Pa 200 10 Pa, 10 10 N E P δ σ − = × = × = × = × Stress: 3 6 2 2 6 10 10 66.667 10 m 66.667 mm 150 10 P A P A σ σ − = × = = = × = × Deformation: 3 6 2 2 9 3 (10 10 )(4) 66.667 10 m 66.667 mm (200 10 )(3 10 ) PL AE PL A E δ δ − − = × = = = × = × × The larger value of A governs: 2 66.667 mm A = 2 4 4(66.667) 4 A A d d π π π = = = 9.21 mm d = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.12 A nylon thread is to be subjected to a 10-N tension. Knowing that 3.2 E = GPa, that the maximum allowable normal stress is 40 MPa, and that the length of the thread must not increase by more than 1%, determine the required diameter of the thread. SOLUTION Stress criterion: 6 9 2 6 9 2 6 40 MPa 40 10 Pa 10 N 10 N : 250 10 m 40 10 Pa 250 10 : 2 2 564.19 10 m 4 P P P A A A A d d σ σ σ π π π − − − = = × = = = = = × × × = = = = × 0.564 mm d = Elongation criterion: 1% 0.01 : L PL AE δ δ = = = 9 9 2 9 6 2 / 10 N/3.2 10 Pa 312.5 10 m / 0.01 312.5 10 2 2 630.78 10 m P E A L A d δ π π − − − × = = = × × = = = × 0.631 mm d = The required diameter is the larger value: 0.631 mm d = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.13 The 4-mm-diameter cable BC is made of a steel with 200 GPa. = E Knowing that the maximum stress in the cable must not exceed 190 MPa and that the elongation of the cable must not exceed 6 mm, find the maximum load P that can be applied as shown. SOLUTION 2 2 6 4 7.2111 m = + = BC L Use bar AB as a free body. 4 0: 3.5 (6) 0 7.2111 0.9509   Σ = − =     = A BC BC M P F P F Considering allowable stress: 6 190 10 Pa σ = × 2 2 6 2 6 6 3 (0.004) 12.566 10 m 4 4 (190 10 )(12.566 10 ) 2.388 10 N π π σ σ − − = = = × = ∴ = = × × = × BC BC A d F F A A Considering allowable elongation: 3 6 10 m δ − = × 6 9 3 3 (12.566 10 )(200 10 )(6 10 ) 2.091 10 N 7.2111 BC BC BC BC F L AE F AE L δ δ − − × × × = ∴ = = = × Smaller value governs. 3 2.091 10 N BC F = × 3 3 0.9509 (0.9509)(2.091 10 ) 1.988 10 N BC P F = = × = × 1.988 kN P = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.14 The aluminum rod ABC ( 6 10.1 10 psi), E = × which consists of two cylindrical portions AB and BC, is to be replaced with a cylindrical steel rod DE ( 6 29 10 psi) E = × of the same overall length. Determine the minimum required diameter d of the steel rod if its vertical deformation is not to exceed the deformation of the aluminum rod under the same load and if the allowable stress in the steel rod is not to exceed 24 ksi. SOLUTION Deformation of aluminum rod. 3 6 2 2 4 4 28 10 12 18 10.1 10 (1.5) (2.25) 0.031376 in. BC AB A AB BC BC AB AB BC PL PL A E A E L L P E A A π π δ = +   = +       × = +     ×   = Steel rod. 0.031376 in. δ = 3 2 6 3 2 3 (28 10 )(30) 0.92317 in (29 10 )(0.031376) 28 10 1.1667 in 24 10 δ δ σ σ × = ∴ = = = × × = ∴ = = = × PL PL A EA E P P A A Required area is the larger value. 2 1.1667 in = A Diameter: 4 (4)(1.6667) A d π π = = 1.219 in. = d 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.15 A 4-ft section of aluminum pipe of cross-sectional area 1.75 in2 rests on a fixed support at A. The 5 8 -in.-diameter steel rod BC hangs from a rigid bar that rests on the top of the pipe at B. Knowing that the modulus of elasticity is 6 29 10 × psi for steel, and 6 10.4 10 × psi for aluminum, determine the deflection of point C when a 15-kip force is applied at C. SOLUTION Rod BC: 6 7 ft 84 in. 29 10 psi BC BC L E = = = × 2 2 2 3 / 6 (0.625) 0.30680 in 4 4 (15 10 )(84) 0.141618 in. (29 10 )(0.30680) π π δ = = = × = = = × BC BC C B BC BC A d PL E A Pipe AB: 6 4 ft 48 in. 10.4 10 psi AB AB L E = = = × 2 3 3 / 6 1.75 in (15 10 )(48) 39.560 10 in. (10.4 10 )(1.75) δ − = × = = = × × AB AB B A AB AB A PL E A Total: 3 / / 39.560 10 0.141618 0.181178 in. δ δ δ − = + = × + = C B A C B 0.1812 in. C δ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.16 The brass tube ( 105 GPa) = AB E has a cross-sectional area of 140 mm2 and is fitted with a plug at A. The tube is attached at B to a rigid plate that is itself attached at C to the bottom of an aluminum cylinder ( 72 GPa) E = with a cross-sectional area of 250 mm2 . The cylinder is then hung from a support at D. In order to close the cylinder, the plug must move down through 1 mm. Determine the force P that must be applied to the cylinder. SOLUTION Shortening of brass tube AB: 2 6 2 9 9 9 6 375 1 376 mm 0.376 m 140 mm 140 10 m 105 10 Pa (0.376) 25.578 10 (105 10 )(140 10 ) δ − − − = + = = = = × = × = = = × × × AB AB AB AB AB AB AB L A E PL P P E A Lengthening of aluminum cylinder CD: 2 6 2 9 9 9 6 0.375 m 250 mm 250 10 m 72 10 Pa (0.375) 20.833 10 (72 10 )(250 10 ) δ − − − = = = × = × = = = × × × CD CD CD CD CD CD CD L A E PL P P E A Total deflection: A AB CD δ δ δ = + where 0.001 m A δ = 9 9 0.001 (25.578 10 20.833 10 ) − − = × + × P 3 21.547 10 N P = × 21.5 kN P = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.17 A 250-mm-long aluminum tube ( 70 GPa) E = of 36-mm outer diameter and 28-mm inner diameter can be closed at both ends by means of single-threaded screw-on covers of 1.5-mm pitch. With one cover screwed on tight, a solid brass rod ( 105 GPa) E = of 25-mm diameter is placed inside the tube and the second cover is screwed on. Since the rod is slightly longer than the tube, it is observed that the cover must be forced against the rod by rotating it one-quarter of a turn before it can be tightly closed. Determine (a) the average normal stress in the tube and in the rod, (b) the deformations of the tube and of the rod. SOLUTION 2 2 2 2 2 6 2 tube 2 2 2 6 2 rod 9 tube 9 6 tube tube rod 6 rod rod ( ) (36 28 ) 402.12 mm 402.12 10 m 4 4 (25) 490.87 mm 490.87 10 m 4 4 (0.250) 8.8815 10 (70 10 )(402.12 10 ) (0.250) (105 10 )(490.87 1 o i A d d A d PL P P E A PL P E A π π π π δ δ − − − − = − = − = = × = = = = × = = = × × × = − = × × 9 6 * 6 * * tube rod tube rod 9 9 6 3 3 9 4.8505 10 0 ) 1 turn 1.5 mm 0.375 mm 375 10 m 4 or 8.8815 10 4.8505 10 375 10 0.375 10 27.308 10 N (8.8815 4.8505)(10 ) P P P P δ δ δ δ δ δ δ − − − − − − − − = − ×   = × = = ×     = + − = × + × = × × = = × + (a) 3 6 tube 6 tube 27.308 10 67.9 10 Pa 402.12 10 σ − × = = = × × P A tube 67.9 MPa σ =  3 6 rod 6 rod 27.308 10 55.6 10 Pa 490.87 10 σ − × = − = − = − × × P A rod 55.6 MPa σ = −  (b) 9 3 6 tube (8.8815 10 )(27.308 10 ) 242.5 10 m δ − − = × × = × tube 0.2425 mm δ =  9 3 6 rod (4.8505 10 )(27.308 10 ) 132.5 10 m δ − − = − × × = − × rod 0.1325 mm δ = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.18 The specimen shown is made from a 1-in.-diameter cylindrical steel rod with two 1.5-in.-outer-diameter sleeves bonded to the rod as shown. Knowing that 6 29 10 psi, = × E determine (a) the load P so that the total deformation is 0.002 in., (b) the corresponding deformation of the central portion BC. SOLUTION (a) i i i i i i PL L P A E E A δ = Σ = Σ 1 2 4 i i i i L P E A d A π δ −   = Σ =     L, in. d, in. A, in2 L/A, in–1 AB 2 1.5 1.7671 1.1318 BC 3 1.0 0.7854 3.8197 CD 2 1.5 1.7671 1.1318 6.083 ← sum 6 1 3 (29 10 )(0.002)(6.083) 9.353 10 lb P − = × = × 9.53 kips P =  (b) 3 6 9.535 10 (3.8197) 29 10 BC BC BC BC BC PL L P A E E A δ × = = = × 3 1.254 10 in. δ − = × 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.19 Both portions of the rod ABC are made of an aluminum for which 70 GPa. E = Knowing that the magnitude of P is 4 kN, determine (a) the value of Q so that the deflection at A is zero, (b) the corresponding deflection of B. SOLUTION (a) 2 2 6 2 (0.020) 314.16 10 m 4 4 AB AB A d π π − = = = × 2 2 3 2 (0.060) 2.8274 10 m 4 4 BC BC A d π π − = = = × Force in member AB is P tension. Elongation: 3 6 9 6 (4 10 )(0.4) 72.756 10 m (70 10 )(314.16 10 ) δ − − × = = = × × × AB AB AB PL EA Force in member BC is Q − P compression. Shortening: 9 9 3 ( ) ( )(0.5) 2.5263 10 ( ) (70 10 )(2.8274 10 ) δ − − − − = = = × − × × BC BC BC Q P L Q P Q P EA For zero deflection at A, BC AB δ δ = 9 6 3 2.5263 10 ( ) 72.756 10 28.8 10 N − − × − = × ∴ − = × Q P Q P 3 3 3 28.3 10 4 10 32.8 10 N Q = × + × = × 32.8 kN = Q  (b) 6 72.756 10 m AB BC B δ δ δ − = = = × 0.0728 mm δ = ↓ AB 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.20 The rod ABC is made of an aluminum for which 70 GPa. E = Knowing that 6 kN = P and 42 kN, = Q determine the deflection of (a) point A, (b) point B. SOLUTION 2 2 6 2 2 2 3 2 (0.020) 314.16 10 m 4 4 (0.060) 2.8274 10 m 4 4 AB AB BC BC A d A d π π π π − − = = = × = = = × 3 3 3 3 6 10 N 6 10 42 10 36 10 N 0.4 m 0.5 m = = × = − = × − × = − × = = AB BC AB BC P P P P Q L L 3 6 6 9 3 6 3 9 (6 10 )(0.4) 109.135 10 m (314.16 10 )(70 10 ) ( 36 10 )(0.5) 90.947 10 m (2.8274 10 )(70 10 ) AB AB AB AB A BC BC BC BC P L A E P L A E δ δ − − − − × = = = × × × − × = = = − × × × (a) 6 6 6 109.135 10 90.947 10 m 18.19 10 m A AB BC δ δ δ − − − = + = × − × = × 0.01819 mm A δ = ↑  (b) 6 90.9 10 m 0.0909 mm B BC δ δ − = = − × = − or 0.0919 mm B δ = ↓ 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.21 Members AB and BC are made of steel 6 ( 29 10 psi) E = × with cross- sectional areas of 0.80 in2 and 0.64 in2 , respectively. For the loading shown, determine the elongation of (a) member AB, (b) member BC. SOLUTION (a) 2 2 6 5 7.810 ft 93.72 in. = + = = AB L Use joint A as a free body. 3 5 0: 28 0 7.810 43.74 kip 43.74 10 lb Σ = − = = = × y AB AB F F F 3 6 (43.74 10 )(93.72) (29 10 )(0.80) δ × = = × AB AB AB AB F L EA 0.1767 in. δ = AB  (b) Use joint B as a free body. 3 6 0: 0 7.810 (6)(43.74) 33.60 kip 33.60 10 lb. 7.810 Σ = − = = = = × x BC AB BC F F F F 3 6 (33.60 10 )(72) (29 10 )(0.64) δ × = = × BC BC BC BC F L EA 0.1304 in. BC δ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.22 The steel frame ( 200 GPa) E = shown has a diagonal brace BD with an area of 1920 mm2 . Determine the largest allowable load P if the change in length of member BD is not to exceed 1.6 mm. SOLUTION 3 2 6 2 2 2 9 9 6 3 3 1.6 10 m, 1920 mm 1920 10 m 5 6 7.810 m, 200 10 Pa (200 10 )(1920 10 )(1.6 10 ) 7.81 78.67 10 N δ δ δ − − − − = × = = × = + = = × = × × × = = = × BD BD BD BD BD BD BD BD BD BD BD BD BD BD A L E F L E A E A F L Use joint B as a free body. 0: x F Σ = 5 0 7.810 − = BD F P 3 3 5 (5)(78.67 10 ) 7.810 7.810 50.4 10 N × = = = × BD P F 50.4 kN = P 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.23 For the steel truss ( 200 GPa) E = and loading shown, determine the deformations of the members AB and AD, knowing that their cross-sectional areas are 2400 mm2 and 1800 mm2 , respectively. SOLUTION Statics: Reactions are 114 kN upward at A and C. Member BD is a zero force member. 2 2 4.0 2.5 4.717 m = + = AB L Use joint A as a free body. 2.5 0: 114 0 4.717 y AB F F Σ = + = 215.10 kN AB F = − 4 0: 0 4.717 x AD AB F F F Σ = + = (4)( 215.10) 182.4 kN 4.717 AD F − = − = Member AB: 3 9 6 ( 215.10 10 )(4.717) (200 10 )(2400 10 ) AB AB AB AB F L EA δ − − × = = × × 3 2.11 10 m − = − × 2.11 mm δ − AB  Member AD: 3 9 6 (182.4 10 )(4.0) (200 10 )(1800 10 ) AD AD AD AD F L EA δ − × = = × × 3 2.03 10 m − = × 2.03 mm δ = AD 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.24 For the steel truss 6 ( 29 10 psi) E = × and loading shown, determine the deformations of the members BD and DE, knowing that their cross- sectional areas are 2 in2 and 3 in2 , respectively. SOLUTION Free body: Portion ABC of truss 0 : (15 ft) (30 kips)(8 ft) (30 kips)(16 ft) 0 48.0 kips E BD BD M F F Σ = − − = = + Free body: Portion ABEC of truss 0: 30 kips 30 kips 0 60.0 kips Σ = + − = = + x DE DE F F F  3 2 6 ( 48.0 10 lb)(8 12 in.) (2 in )(29 10 psi) δ + × × = = × BD PL AE 3 79.4 10 in. δ − = + × BD   3 2 6 ( 60.0 10 lb)(15 12 in.) (3 in )(29 10 psi) δ + × × = = × DE PL AE 3 124.1 10 in. δ − + × DE 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.25 Each of the links AB and CD is made of aluminum 6 ( 10.9 10 psi) E = × and has a cross-sectional area of 0.2 in.2 . Knowing that they support the rigid member BC, determine the deflection of point E. SOLUTION Free body BC: 3 0: (32) (22)(1 10 ) 0 687.5 lb C AB AB M F F Σ = − + × = = 3 0: 687.5 1 10 0 312.5 lb y CD CD F F F Σ = − × + = = 3 6 3 6 (687.5)(18) 5.6766 10 in (10.9 10 )(0.2) (312.5)(18) 2.5803 10 in (10.9 10 )(0.2) δ δ δ δ − − = = = × = × = = = × = × AB AB AB B CD CD CD C F L EA F L EA Deformation diagram: 3 6 3.0963 10 Slope 32 96.759 10 rad δ δ θ − − − × = = = × B C BC L 3 6 3 2.5803 10 (22)(96.759 10 ) 4.7090 10 in δ δ θ − − − = + = × + × = × E C EC L 3 4.71 10 in δ − = × ↓ E 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.26 The length of the 3 32 -in.-diameter steel wire CD has been adjusted so that with no load applied, a gap of 1 16 in. exists between the end B of the rigid beam ACB and a contact point E. Knowing that 6 29 10 psi, E = × determine where a 50-lb block should be placed on the beam in order to cause contact between B and E. SOLUTION Rigid beam ACB rotates through angle θ to close gap. 3 1/16 3.125 10 rad 20 θ − = = × Point C moves downward. 3 3 3 2 2 3 2 4 4(3.125 10 ) 12.5 10 in. 12.5 10 in. 3 6.9029 10 in 4 32 C CD C CD CD CD CD CD A d d F L EA δ θ δ δ π π δ − − − − = = × = × = = ×   = = = ×     = 6 3 3 (29 10 )(6.9029 10 )(12.5 10 ) 12.5 200.18 lb CD CD CD CD EA F L δ − − × × × = = = Free body ACB: 0: 4 (50)(20 ) 0 A CD M F x Σ = − − = (4)(200.18) 20 16.0144 50 3.9856 in. x x − = = = For contact, 3.99 in. x < 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.27 Link BD is made of brass ( 105 GPa) E = and has a cross-sectional area of 240 mm2 . Link CE is made of aluminum ( 72 GPa) E = and has a cross- sectional area of 300 mm2 . Knowing that they support rigid member ABC determine the maximum force P that can be applied vertically at point A if the deflection of A is not to exceed 0.35 mm. SOLUTION Free body member AC: 0: 0.350 0.225 0 1.55556 Σ = − = = C BD BD M P F F P 0: 0.125 0.225 0 0.55556 Σ = − = = B CE CE M P F F P 9 9 6 9 9 6 (1.55556 )(0.225) 13.8889 10 (105 10 )(240 10 ) (0.55556 )(0.150) 3.8581 10 (72 10 )(300 10 ) δ δ δ δ − − − − = = = = × × × = = = = × × × BD BD B BD BD BD CE CE C CE CE CE F L P P E A F L P P E A Deformation Diagram: From the deformation diagram, Slope, 9 9 17.7470 10 78.876 10 0.225 B C BC P P L δ δ θ − − + × = = = × 9 9 9 13.8889 10 (0.125)(78.876 10 ) 23.748 10 δ δ θ − − − = + = × + × = × A B AB L P P P Apply displacement limit. 3 9 0.35 10 m 23.748 10 δ − − = × = × A P 3 14.7381 10 N P = × 14.74 kN P = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.28 Each of the four vertical links connecting the two rigid horizontal members is made of aluminum ( 70 GPa) = E and has a uniform rectangular cross section of 10 × 40 mm. For the loading shown, determine the deflection of (a) point E, (b) point F, (c) point G. SOLUTION Statics. Free body EFG. 3 0 : (400)(2 ) (250)(24) 0 7.5 kN 7.5 10 N F BE BE M F F Σ = − − = = − = − × 3 0 : (400)(2 ) (650)(24) 0 19.5 kN 19.5 10 N E CF CF M F F Σ = − = = = × Area of one link: 2 6 2 (10)(40) 400 mm 400 10 m − = = = × A Length: 300 mm 0.300 m = = L Deformations. 3 6 9 6 3 6 9 6 ( 7.5 10 )(0.300) 80.357 10 m (70 10 )(400 10 ) (19.5 10 )(0.300) 208.93 10 m (70 10 )(400 10 ) BE BE CF CF F L EA F L EA δ δ − − − − − × = = = − × × × × = = = × × ×
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.28 (Continued) (a) Deflection of Point E. | | δ δ = E BF 80.4 m δ μ = ↑ E  (b) Deflection of Point F. F CF δ δ = 209 m F δ μ = ↓  Geometry change. Let θ be the small change in slope angle. 6 6 6 80.357 10 208.93 10 723.22 10 radians 0.400 δ δ θ − − − + × + × = = = × E F EF L (c) Deflection of Point G. G F FG L δ δ θ = + 6 6 6 208.93 10 (0.250)(723.22 10 ) 389.73 10 m δ δ θ − − − = + = × + × = × G F FG L 390 m δ μ = ↓ G 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.29 A vertical load P is applied at the center A of the upper section of a homogeneous frustum of a circular cone of height h, minimum radius a, and maximum radius b. Denoting by E the modulus of elasticity of the material and neglecting the effect of its weight, determine the deflection of point A. SOLUTION Extend the slant sides of the cone to meet at a point O and place the origin of the coordinate system there. From geometry, tan b a h α − = 1 1 , , tan tan tan α α α = = = a b a b r y At coordinate point y, 2 A r π = Deformation of element of height dy: δ = Pdy d AE 2 2 2 tan δ π π α = = P dy P dy d E r E y Total deformation. 1 1 1 1 2 2 2 2 1 1 1 1 1 tan tan tan b b A a a P dy P P y a b E y E E δ π α π α π α     = = − = −          1 1 1 1 2 1 1 ( ) tan b a P b a P a b Eab E π π α − − = = A Ph Eab δ π = ↓ 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.30 A homogeneous cable of length L and uniform cross section is suspended from one end. (a) Denoting by ρ the density (mass per unit volume) of the cable and by E its modulus of elasticity, determine the elongation of the cable due to its own weight. (b) Show that the same elongation would be obtained if the cable were horizontal and if a force equal to half of its weight were applied at each end. SOLUTION (a) For element at point identified by coordinate y, 2 0 0 weight of portion below the point ( ) ( ) ( ) ( ) 1 2 L L P g A L y Pdy gA L y dy g L y d dy EA EA E g L y g dy Ly y E E ρ ρ ρ δ ρ ρ δ = = − − − = = = −   = = −      2 2 2 ρ   = −       g L L E 2 1 2 ρ δ = gL E  (b) Total weight: ρ = W gAL 2 1 1 2 2 δ ρ ρ = = ⋅ = EA EA gL F gAL L L E 1 2 F W = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.31 The volume of a tensile specimen is essentially constant while plastic deformation occurs. If the initial diameter of the specimen is d1, show that when the diameter is d, the true strain is 1 2ln( / ). ε = t d d SOLUTION If the volume is constant, 2 2 1 0 4 4 d L d L π π = 2 2 1 1 2 0 2 1 0 ln ln ε   = =       = =     t d d L L d d d L L d 1 2ln ε = t d d 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.32 Denoting by ε the “engineering strain” in a tensile specimen, show that the true strain is ln (1 ). ε ε = + t SOLUTION 0 0 0 0 ln ln ln 1 ln (1 ) δ δ ε ε   + = = = + = +     t L L L L L Thus ln(1 ) ε ε = + t 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.33 An axial force of 200 kN is applied to the assembly shown by means of rigid end plates. Determine (a) the normal stress in the aluminum shell, (b) the corresponding deformation of the assembly. SOLUTION Let Pa = Portion of axial force carried by shell Pb = Portion of axial force carried by core. , or a a a a a a P L E A P E A L δ δ = = , or b b b b b b P L E A P E A L δ δ = = Thus, ( ) a b a a b b P P P E A E A L δ = + = + with 2 2 3 2 2 3 2 [(0.060) (0.025) ] 2.3366 10 m 4 (0.025) 0.49087 10 m 4 a b A A π π − − = − = × = = × 9 3 9 3 6 [(70 10 )(2.3366 10 ) (105 10 )(0.49087 10 )] 215.10 10 P L P L δ δ − − = × × + × × = × Strain: 3 3 6 6 200 10 0.92980 10 215.10 10 215.10 10 δ ε − × = = = = × × × P L (a) 9 3 6 (70 10 )(0.92980 10 ) 65.1 10 Pa σ ε − = = × × = × a a E 65.1 MPa a σ =  (b) 3 (0.92980 10 )(300 mm) L δ ε − = = × 0.279 mm δ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.34 The length of the assembly shown decreases by 0.40 mm when an axial force is applied by means of rigid end plates. Determine (a) the magnitude of the applied force, (b) the corresponding stress in the brass core. SOLUTION Let Pa = Portion of axial force carried by shell and Pb = Portion of axial force carried by core. , or a a a a a a P L E A P E A L δ δ = = , or b b b b b b P L E A P E A L δ δ = = Thus, ( ) a b a a b b P P P E A E A L δ = + = + with 2 2 3 2 2 3 2 [(0.060) (0.025) ] 2.3366 10 m 4 (0.025) 0.49087 10 m 4 a b A A π π − − = − = × = = × 9 3 9 3 6 [(70 10 )(2.3366 10 ) (105 10 )(0.49087 10 )] 215.10 10 δ δ − − = × × + × × = × P L L with 0.40 mm, 300 mm L δ = = (a) 6 3 0.40 (215.10 10 ) 286.8 10 N 300 P = × = × 287 kN P =  (b) 9 3 6 3 (105 10 )(0.40 10 ) 140 10 Pa 300 10 δ σ − − × × = = = = × × b b b b P E A L 140.0MPa σ = b 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.35 A 4-ft concrete post is reinforced with four steel bars, each with a 3 4 -in. diameter. Knowing that 6 29 10 s E = × psi and 6 3.6 10 c E = × psi, determine the normal stresses in the steel and in the concrete when a 150-kip axial centric force P is applied to the post. SOLUTION 2 2 3 4 1.76715 in 4 4 π     = =           s A 2 2 8 62.233 in = − = c s A A 6 s 6 (48) 0.93663 10 (1.76715)(29 10 ) s s s s s P L P P A E δ − = = = × × 6 c 6 (48) 0.21425 10 (62.233)(3.6 10 ) c c c c c P L P P A E δ − = = = × × But : s c δ δ = 6 6 0.93663 10 0.21425 10 s c P P − − × = × 0.22875 s c P P = (1) Also: 150 kips s c P P P + = = (2) Substituting (1) into (2): 1.22875 150 kips c P = 122.075 kips c P = From (1): 0.22875(122.075) 27.925 kips s P = = 27.925 1.76715 s s s P A σ = − = − 15.80 ksi s σ = −  122.075 62.233 c c c P A σ = − = − 1.962 ksi c σ = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.36 A 250-mm bar of 15 30-mm × rectangular cross section consists of two aluminum layers, 5-mm thick, brazed to a center brass layer of the same thickness. If it is subjected to centric forces of magnitude P = 30 kN, and knowing that Ea = 70 GPa and Eb = 105 GPa, determine the normal stress (a) in the aluminum layers, (b) in the brass layer. SOLUTION For each layer, 2 6 2 (30)(5) 150 mm 150 10 m A − = = = × Let load on each aluminum layer load on brass layer = = a b P P Deformation. a b a b P L P L E A E A δ = = 105 1.5 70 = = = b b a a a a E P P P P E Total force. 2 3.5 = + = a b a P P P P Solving for Pa and Pb, 2 3 7 7 a b P P P P = = (a) 3 6 6 2 2 30 10 57.1 10 Pa 7 7 150 10 a a P P A A σ − × = − = − = − = − × × 57.1 MPa a σ = −  (b) 3 6 6 3 3 30 10 85.7 10 Pa 7 7 150 10 b b P P A A σ − × = − = − = − = − × × 85.7 MPa b σ = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.37 Determine the deformation of the composite bar of Prob. 2.36 if it is subjected to centric forces of magnitude 45 kN. P = PROBLEM 2.36 A 250-mm bar of 15× 30-mm rectangular cross section consists of two aluminum layers, 5-mm thick, brazed to a center brass layer of the same thickness. If it is subjected to centric forces of magnitude 30 P = kN, and knowing that 70 a E = GPa and 105 b E = GPa, determine the normal stress (a) in the aluminum layers, (b) in the brass layer. SOLUTION For each layer, 2 6 2 (30)(5) 150 mm 150 10 m A − = = = × Let load on each aluminum layer load on brass layer = = a b P P Deformation. a b a b P L P L E A E A δ = − = − 105 1.5 70 = = = b b a a a a E P P P P E Total force. 2 3.5 Pa a b P P P = + = 2 7 a P P = 3 3 9 6 6 2 7 2 (45 10 )(250 10 ) 7 (70 10 )(150 10 ) 306 10 m a a a P L PL E A E A δ − − − = − = − × × = − × × = − × 0.306 mm δ = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.38 Compressive centric forces of 40 kips are applied at both ends of the assembly shown by means of rigid plates. Knowing that Es 6 29 10 psi = × and 6 10.1 10 psi, a E = × determine (a) the normal stresses in the steel core and the aluminum shell, (b) the deformation of the assembly. SOLUTION Let portion of axial force carried by shell portion of axial force carried by core = = a s P P a a a a a a s s s s s s P L E A P E A L P L E A P E A L δ δ δ δ = = = = Total force. ( ) a s a a s s P P P E A E A L δ = + = + a a s s P L E A E A δ ε = = + Data: 3 2 2 2 2 2 0 2 2 2 40 10 lb ( ) (2.5 1.0) 4.1233 in 4 4 (1) 0.7854 in 4 4 a i s P A d d A d π π π π = × = − = − = = = = 3 6 6 6 40 10 620.91 10 (10.1 10 )(4.1233) (29 10 )(0.7854) ε − − × = = − × × + × (a) 6 6 3 (29 10 )( 620.91 10 ) 18.01 10 psi s s E σ ε − = = × − × = − × 18.01 ksi −   6 6 3 (10.1 10 )(620.91 10 ) 6.27 10 psi a a E σ ε − = = × × = − ×  6.27 ksi −  (b) 6 3 (10)(620.91 10 ) 6.21 10 L δ ε − − = = × = − × 3 6.21 10 in. δ − = − × 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.39 Three wires are used to suspend the plate shown. Aluminum wires of 1 8 -in. diameter are used at A and B while a steel wire of 1 12 -in.diameter is used at C. Knowing that the allowable stress for aluminum 6 ( 10.4 10 psi) a E = × is 14 ksi and that the allowable stress for steel 6 ( 29 10 psi) s E = × is 18 ksi, determine the maximum load P that can be applied. SOLUTION By symmetry, , A B P P = and A B δ δ = Also, C A B δ δ δ δ = = = Strain in each wire: , 2 2 A B C A L L δ δ ε ε ε ε = = = = Determine allowable strain. Wires A&B: 3 3 6 4 14 10 1.3462 10 10.4 10 2 2.6924 10 A A A C A E σ ε ε ε − − × = = = × × = = × Wire C: 3 3 6 6 18 10 0.6207 10 29 10 1 0.3103 10 2 C C C A B C E σ ε ε ε ε − − × = = = × × = = = × Allowable strain for wire C governs, ∴ 3 18 10 psi C σ = × 2 6 6 2 3 1 (10.4 10 )(0.3103 10 ) 39.61 lb 4 8 39.61 lb 1 (18 10 ) 98.17 lb 4 12 σ ε ε π π σ ε σ − = =   = × × =     =   = = = × =     A A A A A A A B C C C C C C E P A E P E P A For equilibrium of the plate, 177.4 lb = + + = A B C P P P P 177.4 lb = P 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.40 A polystyrene rod consisting of two cylindrical portions AB and BC is restrained at both ends and supports two 6-kip loads as shown. Knowing that 6 0.45 10 psi, E = × determine (a) the reactions at A and C, (b) the normal stress in each portion of the rod. SOLUTION (a) We express that the elongation of the rod is zero: 2 2 4 4 0 BC BC AB AB AB BC P L P L d E d E π π δ = + = But AB A BC C P R P R = + = − Substituting and simplifying: 2 2 0 C BC A AB AB BC R L R L d d − = 2 2 25 2 15 1.25     = =         BC AB C A A BC AB d L R R R L d 4.2667 C A R R = (1) From the free body diagram: 12 kips A C R R + = (2) Substituting (1) into (2): 5.2667 12 A R = 2.2785 kips A R = 2.28 kips A R = ↑  From (1): 4.2667(2.2785) 9.7217 kips C R = = 9.72 kips C R = ↑  (b) 2 4 2.2785 (1.25) π σ + = = = AB A AB AB AB P R A A 1.857 ksi AB σ = +  2 4 9.7217 (2) BC C BC BC BC P R A A π σ − − = = = 3.09 ksi BC σ = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.41 Two cylindrical rods, one of steel and the other of brass, are joined at C and restrained by rigid supports at A and E. For the loading shown and knowing that 200 GPa s E = and 105 GPa, b E = determine (a) the reactions at A and E, (b) the deflection of point C. SOLUTION A to C: 9 2 3 2 3 2 6 200 10 Pa (40) 1.25664 10 mm 1.25664 10 m 4 251.327 10 N E A EA π − = × = = × = × = × C to E: 9 2 2 6 2 6 105 10 Pa (30) 706.86 mm 706.86 10 m 4 74.220 10 N E A EA π − = × = = = × = × A to B: 6 12 180 mm 0.180 m (0.180) 251.327 10 716.20 10 A A AB A P R L R PL EA R δ − = = = = = × = × B to C: 3 3 6 12 6 60 10 120 mm 0.120 m ( 60 10 )(0.120) 251.327 10 447.47 10 26.848 10 A A BC A P R L R PL EA R δ − − = − × = = − × = = × = × − ×
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.41 (Continued) C to D: 3 3 6 9 6 60 10 100 mm 0.100 m ( 60 10 )(0.100) 74.220 10 1.34735 10 80.841 10 A A BC A P R L R PL EA R δ − − = − × = = − × = = × = × − × D to E: 3 3 6 9 6 100 10 100 mm 0.100 m ( 100 10 )(0.100) 74.220 10 1.34735 10 134.735 10 A A DE A P R L R PL EA R δ − − = − × = = − × = = × = × − × A to E: 9 6 3.85837 10 242.424 10 AE AB BC CD DE A R δ δ δ δ δ − − = + + + = × − × Since point E cannot move relative to A, 0 AE δ = (a) 9 6 3 3.85837 10 242.424 10 0 62.831 10 N A A R R − − × − × = = × 62.8 kN = ← A R  3 3 3 3 100 10 62.8 10 100 10 37.2 10 N E A R R = − × = × − × = − × 37.2 kN = ← E R  (b) 9 6 1.16367 10 26.848 10 C AB BC A R δ δ δ − − = + = × − × 9 3 6 6 (1.16369 10 )(62.831 10 ) 26.848 10 46.3 10 m − − − = × × − × = × 46.3 m C δ μ = → 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.42 Solve Prob. 2.41, assuming that rod AC is made of brass and rod CE is made of steel. PROBLEM 2.41 Two cylindrical rods, one of steel and the other of brass, are joined at C and restrained by rigid supports at A and E. For the loading shown and knowing that 200 s E = GPa and 105 GPa, b E = determine (a) the reactions at A and E, (b) the deflection of point C. SOLUTION A to C: 9 2 3 2 3 2 6 105 10 Pa (40) 1.25664 10 mm 1.25664 10 m 4 131.947 10 N E A EA π − = × = = × = × = × C to E: 9 2 2 6 2 6 200 10 Pa (30) 706.86 mm 706.86 10 m 4 141.372 10 N E A EA π − = × = = = × = × A to B: 6 9 180 mm 0.180 m (0.180) 131.947 10 1.36418 10 A A AB A P R L R PL EA R δ − = = = = = × = × B to C: 3 3 6 12 6 60 10 120 mm 0.120 m ( 60 10 )(0.120) 131.947 10 909.456 10 54.567 10 A A BC A P R L R PL EA R δ − − = − × = = − × = = × = × − × C to D: 3 3 6 12 6 60 10 100 mm 0.100 m ( 60 10 )(0.100) 141.372 10 707.354 10 42.441 10 A A CD A P R L R PL EA R δ − − = − × = = − × = = × = × − ×
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.42 (Continued) D to E: 3 3 6 12 6 100 10 100 mm 0.100 m ( 100 10 )(0.100) 141.372 10 707.354 10 70.735 10 A A DE A P R L R PL EA R δ − − = − × = = − × = = × = × − × A to E: 9 6 3.68834 10 167.743 10 AE AB BC CD DE A R δ δ δ δ δ − − = + + + = × − × Since point E cannot move relative to A, 0 AE δ = (a) 9 6 3 3.68834 10 167.743 10 0 45.479 10 N A A R R − − × − × = = × 45.5 kN = ← A R  3 3 3 3 100 10 45.479 10 100 10 54.521 10 E A R R = − × = × − × = − × 54.5 kN = ← E R  (b) 9 6 2.27364 10 54.567 10 C AB BC A R δ δ δ − − = + = × − × 9 3 6 6 (2.27364 10 )(45.479 10 ) 54.567 10 48.8 10 m − − − = × × − × = × 48.8 m C δ μ = → 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.43 The rigid bar ABCD is suspended from four identical wires. Determine the tension in each wire caused by the load P shown. SOLUTION Deformations Let θ be the rotation of bar ABCD and , , A B C δ δ δ and D δ be the deformations of wires A, B, C, and D. From geometry, B A L δ δ θ − = B A L δ δ θ = + 2 2 C A B A L δ δ θ δ δ = + = − (1) 3 3 2 D A B A L δ δ θ δ δ = + = − (2) Since all wires are identical, the forces in the wires are proportional to the deformations. 2 C B A T T T = − (1′) 3 2 D B A T T T = − (2′)
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.43 (Continued) Use bar ABCD as a free body. 0: 2 0 C A B D M LT LT LT Σ = − − + = (3) 0: 0 y A B C D F T T T T P Σ = + + + − = (4) Substituting (2′) into (3) and dividing by L, 4 2 0 2 A B B A T T T T − + = = (3′) Substituting (1′), (2′), and (3′) into (4), 2 3 4 0 A A A A T T T T P + + + − = 10 A T P = 1 10 A T P =  1 2 (2) 10 B A T T P   = =     1 5 B T P =  1 1 (2) 5 10 C T P P     = −         3 10 C T P =  1 1 (3) (2) 5 10 D T P P     = −         2 5 D T P = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.44 The rigid bar AD is supported by two steel wires of 1 16 -in. diameter 6 ( 29 10 psi) = × E and a pin and bracket at D. Knowing that the wires were initially taut, determine (a) the additional tension in each wire when a 120-lb load P is applied at B, (b) the corresponding deflection of point B. SOLUTION Let θ be the rotation of bar ABCD. Then 24 8 A C δ θ δ θ = =  AE AE A P L AE δ = 6 2 1 4 16 3 (29 10 ) ( ) (24 ) 15 142.353 10 A AE AE EA P L π θ δ θ × = = = × CF CF C P L AE δ = ( ) 2 6 1 4 16 3 (29 10 ) (8 ) 8 88.971 10 C CF CF EA P L π θ δ θ × = = = × Using free body ABCD, 0: D M Σ = 3 3 3 24 16 8 0 24(142.353 10 ) 16(120) 8(88.971 10 ) 0 0.46510 10 rad θ θ θ − − + − = − × + − × = = × AE CF P P P 哷 (a) 3 3 (142.353 10 ) (0.46510 10 ) AE P − = × × 66.2 lb AE P =  3 3 (88.971 10 ) (0.46510 10 ) CF P − = × × 41.4 lb CF P =  (b) 3 16 16(0.46510 10 ) B δ θ − = = × 3 7.44 10 in. B δ − = × ↓ 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.45 The steel rods BE and CD each have a 16-mm diameter ( 200 GPa); E = the ends of the rods are single-threaded with a pitch of 2.5 mm. Knowing that after being snugly fitted, the nut at C is tightened one full turn, determine (a) the tension in rod CD, (b) the deflection of point C of the rigid member ABC. SOLUTION Let θ be the rotation of bar ABC as shown. Then 0.15 0.25 B C δ θ δ θ = = But turn CD CD C CD CD P L E A δ δ = − turn 9 2 4 3 6 ( ) (200 10 Pa) (0.016 m) (0.0025m 0.25 ) 2m 50.265 10 5.0265 10 CD CD CD C CD E A P L π δ δ θ θ = − × = − = × − × or BE BE BE BE B BE B BE BE BE P L E A P E A L δ δ = = 9 2 4 6 (200 10 Pa) (0.016 m) (0.15 ) 3 m 2.0106 10 BE P π θ θ × = = × From free body of member ABC: 0: 0.15 0.25 0 A BE CD M P P Σ = − = 6 3 6 0.15(2.0106 10 ) 0.25(50.265 10 5.0265 10 ) 0 θ θ × − × − × = 3 8.0645 10 rad θ − = × (a) 3 6 3 50.265 10 5.0265 10 (8.0645 10 ) CD P − = × − × × 3 9.7288 10 N = × 9.73 kN CD P =  (b) 3 0.25 0.25(8.0645 10 ) C δ θ − = = × 3 2.0161 10 m − = × 2.02 mm C δ = ← 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.46 Links BC and DE are both made of steel 6 ( 29 10 psi) E = × and are 1 2 in. wide and 1 4 in. thick. Determine (a) the force in each link when a 600-lb force P is applied to the rigid member AF shown, (b) the corresponding deflection of point A. SOLUTION Let the rigid member ACDF rotate through small angle θ clockwise about point F. Then 4 in. 2 in. δ δ θ δ δ θ = = → = − = → C BC D DE or FL EA F EA L δ δ = = For links: 2 6 6 6 6 1 1 0.125 in 2 4 4 in. 5 in. (29 10 )(0.125)(4 ) 3.625 10 4 (29 10 )(0.125)( 2 ) 1.45 10 5 δ θ θ δ θ θ    = =       = = × = = = × × − = = = − × BC DE BC BC BC DE DE DE A L L EA F L EA F L Use member ACDF as a free body. 6 6 6 3 0 : 8 4 2 0 1 1 2 4 1 1 600 (3.625 10 ) ( 1.45 10 ) 2.175 10 2 4 + 0.27586 10 rad F BC DE BC DE M P F F P F F θ θ θ θ − Σ = − + = = − = × − − × = × = × 哶 (a) 6 3 (3.625 10 )(0.27586 10 ) BC F − = × × 1000 lb BC F =  6 3 (1.45 10 )(0.27586 10 ) DE F − = − × × 400 lb = − DE F  (b) Deflection at Point A. 3 8 (8)(0.27586 10 ) A δ θ − = = × 3 2.21 10 in δ − = × → A 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.47 The concrete post 6 ( 3.6 10 c E = × psi and 6 5.5 10 / F) c α − = × ° is reinforced with six steel bars, each of 7 8 -in. diameter 6 ( 29 10 s E = × psi and 6 6.5 10 / F). s α − = × ° Determine the normal stresses induced in the steel and in the concrete by a temperature rise of 65°F. SOLUTION 2 2 2 7 6 6 3.6079 in 4 4 8 π π   = = =     s A d 2 2 2 10 10 3.6079 96.392 in = − = − = c s A A Let c P = tensile force developed in the concrete. For equilibrium with zero total force, the compressive force in the six steel rods equals . c P Strains: ( ) ( ) c c s s c c s s c c P P T T E A E A ε α ε α = − + Δ = + Δ Matching: c s ε ε = ( ) ( ) c c c s c c s s P P T T E A E A α α + Δ = − + Δ 6 6 6 3 1 1 ( )( ) 1 1 (1.0 10 )(65) (3.6 10 )(96.392) (29 10 )(3.6079) 5.2254 10 lb α α −   + = − Δ       + = ×   × ×   = × c s c c c s s c c P T E A E A P P 3 5.2254 10 54.210 psi 96.392 c c c P A σ × = = = 54.2 psi c σ =  3 5.2254 10 1448.32 psi 3.6079 c s s P A σ × = − = − = −  1.448 ksi s σ = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.48 The assembly shown consists of an aluminum shell 6 ( 10.6 10 psi, = × a E αa = 12.9 × 10–6 /°F) fully bonded to a steel core 6 ( 29 10 psi, = × s E αs = 6.5 × 10–6 /°F) and is unstressed. Determine (a) the largest allowable change in temperature if the stress in the aluminum shell is not to exceed 6 ksi, (b) the corresponding change in length of the assembly. SOLUTION Since , a s α α > the shell is in compression for a positive temperature rise. Let 3 6 ksi 6 10 psi a σ = − = − × ( ) 2 2 2 2 2 (1.25 0.75 ) 0.78540 in 4 4 π π = − = − = a o i A d d 2 2 2 (0.75) 0.44179 in 4 4 π π = = = s A d a a s s P A A σ σ = − = where P is the tensile force in the steel core. 3 3 (6 10 )(0.78540) 10.667 10 psi 0.44179 a a s s A A σ σ × = − = = × 3 3 6 3 6 6 ( ) ( ) ( )( ) 10.667 10 6 10 (6.4 10 )( ) 0.93385 10 29 10 10.6 10 s a s a s a s a a s s a T T E E T E E T σ σ ε α α σ σ α α − − = + Δ = + Δ − Δ = − × × × Δ = + = × × × (a) 145.91 F T Δ = ° 145.9 F Δ = ° T  (b) 3 6 3 6 10.667 10 (6.5 10 )(145.91) 1.3163 10 29 10 ε − − × = + × = × × or 3 6 3 6 6 10 (12.9 10 )(145.91) 1.3163 10 10.6 10 ε − − − × = + × = × ×  3 (8.0)(1.3163 10 ) 0.01053 in. δ ε − = = × = L  0.01053 in. δ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.49 The aluminum shell is fully bonded to the brass core and the assembly is unstressed at a temperature of 15 C. ° Considering only axial deformations, determine the stress in the aluminum when the temperature reaches 195 C. ° SOLUTION Brass core: 6 105 GPa 20.9 10 / C E α − = = × ° Aluminum shell: 6 70 GPa 23.6 10 / C E α − = = × ° Let L be the length of the assembly. Free thermal expansion: 195 15 180 C T Δ = − = ° Brass core: ( ) ( ) T b b L T δ α = Δ Aluminum shell: ( ) ( ) T a L T δ α = Δ Net expansion of shell with respect to the core: ( )( ) a b L T δ α α = − Δ Let P be the tensile force in the core and the compressive force in the shell. Brass core: 9 2 2 6 2 105 10 Pa (25) 490.87 mm 4 490.87 10 m ( ) b b P b b b E A PL E A π δ − = × = = = × =
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.49 (Continued) Aluminum shell: 9 2 2 3 2 3 2 70 10 Pa (60 25 ) 4 2.3366 10 mm 2.3366 10 m ( ) ( ) ( )( ) a a P b P a b a b b a a E A PL PL L T KPL E A E A π δ δ δ α α − = × = − = × = × = + − Δ = + = where 9 6 9 3 9 1 1 1 1 1 (105 10 )(490.87 10 ) (70 10 )(2.3366 10 ) 25.516 10 N b b a a K E A E A − − − − = + = + × × × × = × Then 6 6 9 3 ( )( ) (23.6 10 20.9 10 )(180) 25.516 10 19.047 10 N b a T P K α α − − − − Δ = × − × = × = × Stress in aluminum: 3 6 3 19.047 10 8.15 10 Pa 2.3366 10 a a P A σ − × = − = − = − × × 8.15 MPa a σ = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.50 Solve Prob. 2.49, assuming that the core is made of steel ( 200 s E = GPa, 6 11.7 10 / C) s α − = × ° instead of brass. PROBLEM 2.49 The aluminum shell is fully bonded to the brass core and the assembly is unstressed at a temperature of 15 C. ° Considering only axial deformations, determine the stress in the aluminum when the temperature reaches 195 C. ° SOLUTION Aluminum shell: 6 70 GPa 23.6 10 / C α − = = × ° E Let L be the length of the assembly. Free thermal expansion: 195 15 180 C T Δ = − = ° Steel core: ( ) ( ) T s s L T δ α = Δ Aluminum shell: ( ) ( ) T a a L T δ α = Δ Net expansion of shell with respect to the core: ( )( ) a s L T δ α α = − Δ Let P be the tensile force in the core and the compressive force in the shell. Steel core: 9 2 2 6 2 200 10 Pa, (25) 490.87 mm 490.87 10 m 4 ( ) π δ − = × = = = × = s s P s s s E A PL E A Aluminum shell: 9 2 2 3 2 3 2 70 10 Pa ( ) (60 25) 2.3366 10 mm 2.3366 10 m 4 ( ) ( ) δ π δ δ δ − = × = = − = × = × = + a P a a a a P s P a E PL E A A ( )( ) α α − Δ = + = a s s s a a PL PL L T KPL E A E A where 9 6 9 3 9 1 1 1 1 1 (200 10 )(490.87 10 ) (70 10 )(2.3366 10 ) 16.2999 10 N − − − − = + = + × × × × = × s s a a K E A E A
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.50 (Continued) Then 6 6 3 9 ( )( ) (23.6 10 11.7 10 )(180) 131.41 10 N 16.2999 10 α α − − − − Δ × − × = = = × × a s T P K Stress in aluminum: 3 6 3 131.19 10 56.2 10 Pa 2.3366 10 a a P A σ − × = − = − = − × × 56.2 MPa a σ = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.51 A rod consisting of two cylindrical portions AB and BC is restrained at both ends. Portion AB is made of steel ( 200 GPa, s E = 6 11.7 10 / C) s α − = × ° and portion BC is made of brass ( 105 GPa, b E = 6 20.9 10 / C). b α − = × ° Knowing that the rod is initially unstressed, determine the compressive force induced in ABC when there is a temperature rise of 50 C. ° SOLUTION 2 2 2 6 2 2 2 3 2 3 2 (30) 706.86 mm 706.86 10 m 4 4 (50) 1.9635 10 mm 1.9635 10 m 4 4 AB AB BC BC A d A d π π π π − − = = = = × = = = × = × Free thermal expansion: 6 6 6 ( ) ( ) (0.250)(11.7 10 )(50) (0.300)(20.9 10 )(50) 459.75 10 m T AB s BC b L T L T δ α α − − − = Δ + Δ = × + × = × Shortening due to induced compressive force P: 9 6 9 3 9 0.250 0.300 (200 10 )(706.86 10 ) (105 10 )(1.9635 10 ) 3.2235 10 P s AB b BC PL PL E A E A P P P δ − − − = + = + × × × × = × For zero net deflection, P T δ δ = 9 6 3 3.2235 10 459.75 10 142.62 10 N P P − − × = × = × 142.6 kN P = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.52 A steel railroad track 6 s ( 200 GPa, 11.7 10 /°C) s E α − = = × was laid out at a temperature of 6°C. Determine the normal stress in the rails when the temperature reaches 48°C, assuming that the rails (a) are welded to form a continuous track, (b) are 10 m long with 3-mm gaps between them. SOLUTION (a) 6 3 ( ) (11.7 10 )(48 6)(10) 4.914 10 m T T L δ α − − = Δ = × − = × 12 9 (10) 50 10 200 10 P PL L AE E σ σ δ σ − = = = = × × 3 12 4.914 10 50 10 0 T P δ δ δ σ − − = + = × + × = 6 98.3 10 Pa σ = − × 98.3 MPa σ = − (b) 3 12 3 4.914 10 50 10 3 10 T P δ δ δ σ − − − = + = × + × = × 3 3 12 6 3 10 4.914 10 50 10 38.3 10 Pa σ − − − × − × = × = − × 38.3 MPa σ = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.53 A rod consisting of two cylindrical portions AB and BC is restrained at both ends. Portion AB is made of steel 6 ( 29 10 psi, = × s E 6 6.5 10 / F) α − = × ° s and portion BC is made of aluminum 6 ( 10.4 10 psi, = × a E 6 13.3 10 /°F). α − = × a Knowing that the rod is initially unstressed, determine (a) the normal stresses induced in portions AB and BC by a temperature rise of 70°F, (b) the corresponding deflection of point B. SOLUTION 2 2 2 2 (2.25) 3.9761 in (1.5) 1.76715 in 4 4 π π = = = = AB BC A A Free thermal expansion. 70 F T Δ = ° Total: 6 3 6 3 3 ( ) ( ) (24)(6.5 10 )(70) 10.92 10 in ( ) ( ) (32)(13.3 10 (70) 29.792 10 in. ( ) ( ) 40.712 10 in. T AB AB s T BC BC a T T AB T BC L T L T δ α δ α δ δ δ − − − − − = Δ + × = × = Δ = × = × = + = × Shortening due to induced compressive force P. 9 6 9 6 24 ( ) 208.14 10 (29 10 )(3.9761) 32 ( ) 1741.18 10 (10.4 10 )(1.76715) δ δ − − = = = × × = = = × × AB P AB s AB BC P BC a BC PL P P E A PL P P E A Total: 9 ( ) ( ) 1949.32 10 δ δ δ − = + = × P P AB P BC P For zero net deflection, P T δ δ = 9 3 1949.32 10 40.712 10 P − − × = × 3 20.885 10 lb P = × (a) 3 3 20.885 10 5.25 10 psi 3.9761 AB AB P A σ × = − = − = − × 5.25 ksi AB σ = −  3 3 20.885 10 11.82 10 psi 1.76715 BC BC P A σ × = − = − = − × 11.82 ksi BC σ = −  (b) 9 3 3 ( ) (208.14 10 )(20.885 10 ) 4.3470 10 in. P AB δ − − = × × = × 3 3 ( ) ( ) 10.92 10 4.3470 10 B T AB P AB δ δ δ − − = → + ← = × → + × ← 3 6.57 10 in. B δ − = × →  or 9 3 3 ( ) (1741.18 10 )(20.885 10 ) 36.365 10 in. P BC δ − − = × × = × 3 3 3 ( ) ( ) 29.792 10 36.365 10 6.57 10 in. B T BC P BC δ δ δ − − − = ← + → = × ← + × → = × → (checks)
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.54 Solve Prob. 2.53, assuming that portion AB of the composite rod is made of aluminum and portion BC is made of steel. PROBLEM 2.53 A rod consisting of two cylindrical portions AB and BC is restrained at both ends. Portion AB is made of steel 6 ( 29 10 psi, = × s E 6 6.5 10 / F) α − = × ° s and portion BC is made of aluminum 6 ( 10.4 10 psi, = × a E 6 13.3 10 /°F). α − = × a Knowing that the rod is initially unstressed, determine (a) the normal stresses induced in portions AB and BC by a temperature rise of 70°F, (b) the corresponding deflection of point B. SOLUTION 2 2 (2.25) 3.9761 in 4 π = = AB A 2 2 (1.5) 1.76715 in 4 π = = BC A Free thermal expansion. 70 F T Δ = ° 6 3 6 3 ( ) ( ) (24)(13.3 10 )(70) 22.344 10 in. ( ) ( ) (32)(6.5 10 )(70) 14.56 10 in. T AB AB a T BC BC s L T L T δ α δ α − − − − = Δ = × = × = Δ = × = × Total: 3 ( ) ( ) 36.904 10 in. T T AB T BC δ δ δ − = + = × Shortening due to induced compressive force P. 9 6 9 6 24 ( ) 580.39 10 (10.4 10 )(3.9761) 32 ( ) 624.42 10 (29 10 )(1.76715) δ δ − − = = = × × = = = × × AB P AB a AB BC P BC s BC PL P P E A PL P P E A Total: 9 ( ) ( ) 1204.81 10 δ δ δ − = + = × P P AB P BC P For zero net deflection, P T δ δ = 9 3 1204.81 10 36.904 10 − − × = × P 3 30.631 10 lb P = × (a) 3 3 30.631 10 7.70 10 psi 3.9761 AB AB P A σ × = − = − = − × 7.70 ksi AB σ = −  3 3 30.631 10 17.33 10 psi 1.76715 BC BC P A σ × = − = − = − × 17.33 ksi BC σ = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.54 (Continued) (b) 9 3 3 ( ) (580.39 10 )(30.631 10 ) 17.7779 10 in. P AB δ − − = × × = × 3 3 ( ) ( ) 22.344 10 17.7779 10 B T AB P AB δ δ δ − − = → + ← = × → + × ← 3 4.57 10 in. B δ − = × →   or 9 3 3 ( ) (624.42 10 )(30.631 10 ) 19.1266 10 in. P BC δ − − = × × = × 3 3 3 ( ) ( ) 14.56 10 19.1266 10 4.57 10 in. (checks) B T BC P BC δ δ δ − − − = ← + → = × ← + × →= × →
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.55 A brass link ( 105 GPa, b E = 6 20.9 10 / C) b α − = × ° and a steel rod (Es 200 GPa, = 6 11.7 10 / C) s α − = × ° have the dimensions shown at a temperature of 20 C. ° The steel rod is cooled until it fits freely into the link. The temperature of the whole assembly is then raised to 45 C. ° Determine (a) the final stress in the steel rod, (b) the final length of the steel rod. SOLUTION Initial dimensions at 20 C. T = ° Final dimensions at 45 C. T = ° 45 20 25 C T Δ = − = ° Free thermal expansion of each part: Brass link: 6 6 ( ) ( ) (20.9 10 )(25)(0.250) 130.625 10 m T b b T L δ α − − = Δ = × = × Steel rod: 6 6 ( ) ( ) (11.7 10 )(25)(0.250) 73.125 10 m T s s T L δ α − − = Δ = × = × At the final temperature, the difference between the free length of the steel rod and the brass link is 6 6 6 6 120 10 73.125 10 130.625 10 62.5 10 m δ − − − − = × + × − × = × Add equal but opposite forces P to elongate the brass link and contract the steel rod. Brass link: 9 105 10 Pa E = × 2 3 2 12 9 3 (2)(50)(37.5) 3750 mm 3.750 10 m (0.250) ( ) 634.92 10 (105 10 )(3.750 10 ) b P A PL P P EA δ − − − = = = × = = = × × × Steel rod: 9 200 10 Pa E = × 2 2 6 2 (30) 706.86 mm 706.86 10 m 4 s A π − = = = × 9 9 6 (0.250) ( ) 1.76838 10 (200 10 )(706.86 10 ) P s s s PL P P E A δ − − = = = × × × 9 6 3 ( ) ( ) : 2.4033 10 62.5 10 26.006 10 N δ δ δ − − + = × = × = × P b P s P P (a) Stress in steel rod: 3 6 6 (26.006 10 ) 36.8 10 Pa 706.86 10 s s P A σ − × = − = − = − × × 36.8 MPa s σ = −  (b) Final length of steel rod: 0 ( ) ( ) f T s P s L L δ δ = + − 6 6 9 3 0.250 120 10 73.125 10 (1.76838 10 )(26.003 10 ) f L − − − = + × + × − × × 0.250147 m = 250.147 mm f L = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.56 Two steel bars 6 ( 200 GPa and 11.7 10 / C) s s E α − = = × ° are used to reinforce a brass bar 6 ( 105 GPa, 20.9 10 / C) b b E α − = = × ° that is subjected to a load 25 kN. P = When the steel bars were fabricated, the distance between the centers of the holes that were to fit on the pins was made 0.5 mm smaller than the 2 m needed. The steel bars were then placed in an oven to increase their length so that they would just fit on the pins. Following fabrication, the temperature in the steel bars dropped back to room temperature. Determine (a) the increase in temperature that was required to fit the steel bars on the pins, (b) the stress in the brass bar after the load is applied to it. SOLUTION (a) Required temperature change for fabrication: 3 0.5 mm 0.5 10 m T δ − = = × Temperature change required to expand steel bar by this amount: 3 6 3 6 , 0.5 10 (2.00)(11.7 10 )( ), 0.5 10 (2)(11.7 10 )( ) 21.368 C T s L T T T T T δ α − − − − = Δ × = × Δ Δ = × = × Δ Δ = ° 21.4 C °  (b) Once assembled, a tensile force P* develops in the steel, and a compressive force P* develops in the brass, in order to elongate the steel and contract the brass. Elongation of steel: 2 6 2 (2)(5)(40) 400 mm 400 10 m s A − = = = × * * 9 * 6 9 (2.00) ( ) 25 10 (400 10 )(200 10 ) P s s s F L P P A E δ − − = = = × × × Contraction of brass: 2 6 2 (40)(15) 600 mm 600 10 m b A − = = = × * * 9 * 6 9 (2.00) ( ) 31.746 10 (600 10 )(105 10 ) P b b b P L P P A E δ − − = = = × × × But ( ) ( ) P s P b δ δ + is equal to the initial amount of misfit: 3 9 * 3 * 3 ( ) ( ) 0.5 10 , 56.746 10 0.5 10 8.811 10 N P s P b P P δ δ − − − + = × × = × = × Stresses due to fabrication: Steel: * 3 * 6 6 8.811 10 22.03 10 Pa 22.03 MPa 400 10 s s P A σ − × = = = × = ×
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.56 (Continued) Brass: * 3 * 6 6 8.811 10 14.68 10 Pa 14.68 MPa 600 10 b b P A σ − × = − = − = − × = − × To these stresses must be added the stresses due to the 25 kN load. For the added load, the additional deformation is the same for both the steel and the brass. Let δ′ be the additional displacement. Also, let Ps and Pb be the additional forces developed in the steel and brass, respectively. 6 9 6 6 9 6 (400 10 )(200 10 ) 40 10 2.00 (600 10 )(105 10 ) 31.5 10 2.00 s b s s b b s s s b b b P L P L A E A E A E P L A E P L δ δ δ δ δ δ δ − − ′ = = × × ′ ′ ′ = = = × × × ′ ′ ′ = = = × Total 3 25 10 N s b P P P = + = × 6 6 3 6 40 10 31.5 10 25 10 349.65 10 m δ δ δ − ′ ′ ′ × + × = × = × 6 6 3 6 6 3 (40 10 )(349.65 10 ) 13.986 10 N (31.5 10 )(349.65 10 ) 11.140 10 N s b P P − − = × × = × = × × = × 3 6 6 3 6 6 13.986 10 34.97 10 Pa 400 10 11.140 10 18.36 10 Pa 600 10 s s s b b b P A P A σ σ − − × = = = × × × = = = × × Add stress due to fabrication. Total stresses: 6 6 6 34.97 10 22.03 10 57.0 10 Pa s σ = × + × = × 57.0 MPa σ = s 6 6 6 18.36 10 14.68 10 3.68 10 Pa b σ = × − × = × 3.68 MPa σ = b 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.57 Determine the maximum load P that may be applied to the brass bar of Prob. 2.56 if the allowable stress in the steel bars is 30 MPa and the allowable stress in the brass bar is 25 MPa. PROBLEM 2.56 Two steel bars ( 200 GPa and 11.7 s s E α = = × 10–6 /°C) are used to reinforce a brass bar ( 105 GPa, 20.9 b b E α = = × 10–6 /°C) that is subjected to a load 25 kN. P = When the steel bars were fabricated, the distance between the centers of the holes that were to fit on the pins was made 0.5 mm smaller than the 2 m needed. The steel bars were then placed in an oven to increase their length so that they would just fit on the pins. Following fabrication, the temperature in the steel bars dropped back to room temperature. Determine (a) the increase in temperature that was required to fit the steel bars on the pins, (b) the stress in the brass bar after the load is applied to it. SOLUTION See solution to Problem 2.56 to obtain the fabrication stresses. * * 22.03 MPa 14.68 MPa s b σ σ = = Allowable stresses: ,all ,all 30 MPa, 25 MPa s b σ σ = = Available stress increase from load. 30 22.03 7.97 MPa 25 14.68 39.68 MPa s b σ σ = − = = + = Corresponding available strains. 6 6 9 6 6 9 7.97 10 39.85 10 200 10 39.68 10 377.9 10 105 10 s s s b b b E E σ ε σ ε − − × = = = × × × = = = × × 6 Smaller value governs 39.85 10 ε − ∴ = × Areas: 2 6 2 (2)(5)(40) 400 mm 400 10 m s A − = = = × 2 6 2 (15)(40) 600 mm 600 10 m b A − = = = × Forces 9 6 6 3 9 6 6 3 (200 10 )(400 10 )(39.85 10 ) 3.188 10 N (105 10 )(600 10 )(39.85 10 ) 2.511 10 N ε ε − − − − − = = × × × = × = = × × × = × s s s b b b P E A P E A Total allowable additional force: 3 3 3 3.188 10 2.511 10 5.70 10 N s b P P P = + = × + × = × 5.70 kN = P 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.58 Knowing that a 0.02-in. gap exists when the temperature is 75 F, ° determine (a) the temperature at which the normal stress in the aluminum bar will be equal to −11 ksi, (b) the corresponding exact length of the aluminum bar. SOLUTION 3 3 3 11 ksi 11 10 psi (11 10 )(2.8) 30.8 10 lb σ σ = − = − × = − = × = × a a a P A Shortening due to P: 3 3 6 6 3 (30.8 10 )(14) (30.8 10 )(18) (15 10 )(2.4) (10.6 10 )(2.8) 30.657 10 in. b a P b b a a PL PL E A E A δ − = + × × = + × × = × Available elongation for thermal expansion: 3 3 0.02 30.657 10 50.657 10 in. T δ − − = + × = × But ( ) ( ) T b b a a L T L T δ α α = Δ + Δ 6 6 6 (14)(12 10 )( ) (18)(12.9 10 )( ) 400.2 10 ) T T T − − − = × Δ + × Δ = × Δ Equating, 6 3 (400.2 10 ) 50.657 10 126.6 F T T − − × Δ = × Δ = ° (a) hot cold 75 126.6 201.6 F T T T = + Δ = + = ° hot 201.6 F = ° T  (b) ( ) a a a a a a PL L T E A δ α = Δ − 3 6 3 6 (30.8 10 )(18) (18)(12.9 10 )(26.6) 10.712 10 in. (10.6 10 )(2.8) − − × = × − = × × 3 exact 18 10.712 10 18.0107in. L − = + × = 18.0107 in. = L 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.59 Determine (a) the compressive force in the bars shown after a temperature rise of 180 F, ° (b) the corresponding change in length of the bronze bar. SOLUTION Thermal expansion if free of constraint: 6 6 3 ( ) ( ) (14)(12 10 )(180) (18)(12.9 10 )(180) 72.036 10 in. T b b a a L T L T δ α α − − − = Δ + Δ = × + × = × Constrained expansion: 0.02in. δ = Shortening due to induced compressive force P: 3 3 72.036 10 0.02 52.036 10 in. P δ − − = × − = × But b a b a P b b a a b b a a PL PL L L P E A E A E A E A δ   = + = +     9 6 6 14 18 995.36 10 (15 10 )(2.4) (10.6 10 )(2.8) P P −   = + = ×   × ×   Equating, 9 3 3 995.36 10 52.036 10 52.279 10 lb P P − − × = × = × (a) 52.3 kips P =  (b) ( ) b b b b b b PL L T E A δ α = Δ − 3 6 3 6 (52.279 10 )(14) (14)(12 10 )(180) 9.91 10 in. (15 10 )(2.4) − − × = × − = × × 3 9.91 10 in. δ − = × b 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.60 At room temperature (20 C) ° a 0.5-mm gap exists between the ends of the rods shown. At a later time when the temperature has reached 140°C, determine (a) the normal stress in the aluminum rod, (b) the change in length of the aluminum rod. SOLUTION 140 20 120 C T Δ = − = ° Free thermal expansion: 6 6 3 ( ) ( ) (0.300)(23 10 )(120) (0.250)(17.3 10 )(120) 1.347 10 m T a a s s L T L T δ α α − − − = Δ + Δ = × + × = × Shortening due to P to meet constraint: 3 3 3 1.347 10 0.5 10 0.847 10 m P δ − − − = × − × = × 9 6 9 6 9 0.300 0.250 (75 10 )(2000 10 ) (190 10 )(800 10 ) 3.6447 10 a s a s P a a s s a a s s PL PL L L P E A E A E A E A P P δ − − −   = + = +       = +   × × × ×   = × Equating, 9 3 3 3.6447 10 0.847 10 232.39 10 N P P − − × = × = × (a) 3 6 6 232.39 10 116.2 10 Pa 2000 10 a a P A σ − × = − = − = − × × 116.2 MPa σ = − a  (b) ( ) a a a a a a PL L T E A δ α = Δ − 3 6 6 9 6 (232.39 10 )(0.300) (0.300)(23 10 )(120) 363 10 m (75 10 )(2000 10 ) − − − × = × − = × × × 0.363 mm δ = a 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.61 A 600-lb tensile load is applied to a test coupon made from 1 16 -in. flat steel plate (E 6 29 10 psi = × and 0.30). v = Determine the resulting change (a) in the 2-in. gage length, (b) in the width of portion AB of the test coupon, (c) in the thickness of portion AB, (d) in the cross-sectional area of portion AB. SOLUTION 2 3 3 6 6 1 1 0.03125 in 2 16 600 19.2 10 psi 0.03125 19.2 10 662.07 10 29 10 σ σ ε −    = =       = = = × × = = = × × x A P A E (a) 6 0 (2.0)(662.07 10 ) x x L δ ε − = = × 3 1.324 10 in. l δ − = ×  6 6 (0.30)(662.07 10 ) 198.62 10 y z x v ε ε ε − − = = − = − × = − × (b) 6 width 0 1 ( 198.62 10 ) 2 y w δ ε −   = = − ×     6 99.3 10 in. w δ − = − ×  (c) 6 thickness 0 1 ( 198.62 10 ) 16 z t δ ε −   = = − ×     6 12.41 10 in. t δ − = − ×  (d) 0 0 (1 ) (1 ) y z A wt w t ε ε = = + + 0 0 (1 ) y z y z w t ε ε ε ε = + + + 0 0 0 6 6 6 2 ( ) 1 1 ( 198.62 10 198.62 10 negligible term) 2 16 12.41 10 in ε ε ε ε − − − Δ = − = + +    = − × − × +       = − × y z y z A A A w t 6 2 12.41 10 in − Δ = − × A 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.62 In a standard tensile test, a steel rod of 22-mm diameter is subjected to a tension force of 75 kN. Knowing that 0.3 v = and 200 GPa, E = determine (a) the elongation of the rod in a 200-mm gage length, (b) the change in diameter of the rod. SOLUTION 3 2 2 6 2 75 kN 75 10 N (0.022) 380.13 10 m 4 4 P A d π π − = = × = = = × 3 6 6 6 6 9 6 75 10 197.301 10 Pa 380.13 10 197.301 10 986.51 10 200 10 (200 mm)(986.51 10 ) x x x P A E L σ σ ε δ ε − − − × = = = × × × = = = × × = = × (a) 0.1973 mm δ = x   6 6 (0.3)(986.51 10 ) 295.95 10 y x v ε ε − − = − = − × = − ×   6 (22 mm)( 295.95 10 ) y y d δ ε − = = − ×   (b) 0.00651 mm δ = − y 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.63 A 20-mm-diameter rod made of an experimental plastic is subjected to a tensile force of magnitude P = 6 kN. Knowing that an elongation of 14 mm and a decrease in diameter of 0.85 mm are observed in a 150-mm length, determine the modulus of elasticity, the modulus of rigidity, and Poisson’s ratio for the material. SOLUTION Let the y-axis be along the length of the rod and the x-axis be transverse. 2 2 6 2 3 3 6 6 (20) 314.16 mm 314.16 10 m 6 10 N 4 6 10 19.0985 10 Pa 314.16 10 14 mm 0.093333 150 mm y y y A P P A L π σ δ ε − − = = = × = × × = = = × × = = = Modulus of elasticity: 6 6 19.0985 10 204.63 10 Pa 0.093333 y y E σ ε × = = = × 205 MPa E =  0.85 0.0425 20 x x d δ ε = = − = − Poisson’s ratio: 0.0425 0.093333 x y v ε ε − = − = − 0.455 v =  Modulus of rigidity: 6 6 204.63 10 70.31 10 Pa 2(1 ) (2)(1.455) E G v × = = = × + 70.3 MPa G = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.64 The change in diameter of a large steel bolt is carefully measured as the nut is tightened. Knowing that 6 29 10 psi E = × and 0.30, v = determine the internal force in the bolt, if the diameter is observed to decrease by 3 0.5 10 in. − × SOLUTION 3 3 3 0.5 10 in. 2.5 in. 0.5 10 0.2 10 2.5 y y y d d δ ε ε − − − = − × = × = = − = − × 3 3 0.2 10 : 0.66667 10 0.3 y y x x v v ε ε ε ε − − − × = − = = = × 6 3 3 (29 10 )(0.66667 10 ) 19.3334 10 psi x x E σ ε − = = × × = × 2 2 2 (2.5) 4.9087 in 4 4 π π = = = A d 3 3 (19.3334 10 )(4.9087) 94.902 10 lb x F A σ = = × = × 94.9 kips F = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.65 A 2.5-m length of a steel pipe of 300-mm outer diameter and 15-mm wall thickness is used as a column to carry a 700-kN centric axial load. Knowing that 200 GPa E = and 0.30, v = determine (a) the change in length of the pipe, (b) the change in its outer diameter, (c) the change in its wall thickness. SOLUTION ( ) 3 2 2 2 2 3 2 0.3 m 0.015 m 2.5 m 2 0.3 2(0.015) 0.27 m 700 10 N (0.3 0.27 ) 13.4303 10 m 4 4 π π − = = = = − = − = = × = − = − = × o i o o i d t L d d t P A d d (a) 3 9 3 (700 10 )(2.5) (200 10 )(13.4303 10 ) PL EA δ − × = − = − × × 6 651.51 10 m − = − × 0.652 mm δ = −  6 6 651.51 10 260.60 10 2.5 L δ ε − − − × = = = − × 6 LAT 6 (0.30)( 260.60 10 ) 78.180 10 v ε ε − − = − = − − × = × (b) 6 LAT (300 mm)(78.180 10 ) ε − Δ = = × o o d d 0.0235 mm Δ = o d  (c) 6 LAT (15 mm)(78.180 10 ) t tε − Δ = = ×  0.001173 mm t Δ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.66 An aluminum plate ( 74 E = GPa and 0.33) v = is subjected to a centric axial load that causes a normal stress σ. Knowing that, before loading, a line of slope 2:1 is scribed on the plate, determine the slope of the line when 125 σ = MPa. SOLUTION The slope after deformation is 2(1 ) tan 1 y x ε θ ε + = + 6 3 9 3 3 125 10 1.6892 10 74 10 (0.33)(1.6892 10 ) 0.5574 10 2(1 0.0005574) tan 1.99551 1 0.0016892 x x y x E v σ ε ε ε θ − − − × = = = × × = − = − × = − × − = = + tan 1.99551 θ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.67 The block shown is made of a magnesium alloy, for which 45 E = GPa and 0.35. v = Knowing that 180 x σ = − MPa, determine (a) the magnitude of y σ for which the change in the height of the block will be zero, (b) the corresponding change in the area of the face ABCD, (c) the corresponding change in the volume of the block. SOLUTION (a) 6 0 0 0 1 ( ) (0.35)( 180 10 ) y y z y x y z y x v v E v δ ε σ ε σ σ σ σ σ = = = = − − = = − × 6 63 10 Pa = − × 63 MPa y σ = −  6 3 9 6 3 9 1 (0.35)( 243 10 ) ( ) ( ) 1.89 10 45 10 1 157.95 10 ( ) 3.51 10 45 10 z z x y x y x y x x y Z v v v E E v v v E E ε σ σ σ σ σ σ σ ε σ σ σ − − − × = − − = − + = = − × × − × = − − = = − = − × × (b) 0 0 (1 ) (1 ) (1 ) ( ) ( ) x z x x z z x z x z x z x z x z x z x z x z A L L A L L L L A A A L L L L ε ε ε ε ε ε ε ε ε ε ε ε = = + + = + + + Δ = − = + + ≈ + 3 3 (100 mm)(25 mm)( 3.51 10 1.89 10 ) A − − Δ = − × − × 2 13.50 mm A Δ = −  (c) 0 0 (1 ) (1 ) (1 ) (1 ) ( small terms) ε ε ε ε ε ε ε ε ε ε ε ε ε ε ε ε ε ε = = + + + = + + + + + + + Δ = − = + + + x y z x x y y z z x y z x y z x y y z z x x y z x y z x y z V L L L V L L L L L L V V V L L L 3 3 (100)(40)(25)( 3.51 10 0 1.89 10 ) − − Δ = − × + − × V 3 540 mm Δ = − V 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.68 A 30-mm square was scribed on the side of a large steel pressure vessel. After pressurization, the biaxial stress condition at the square is as shown. For 200 GPa E = and 0.30, v = determine the change in length of (a) side AB, (b) side BC, (c) diagnonal AC. SOLUTION Given: 80 MPa 40 MPa x y σ σ = = Using Eq’s (2.28): 6 3 1 80 0.3(40) ( ) 340 10 200 10 x x y v E ε σ σ − − = − = = × × 6 3 1 40 0.3(80) ( ) 80 10 200 10 y y x v E ε σ σ − − = − = = × × (a) Change in length of AB. 6 3 ( ) (30 mm)(340 10 ) 10.20 10 mm AB x AB δ ε − − = = × = × 10.20 m AB δ μ =  (b) Change in length of BC. 6 3 ( ) (30 mm)(80 10 ) 2.40 10 mm BC y BC δ ε − − = = × = × 2.40 m BC δ μ =  (c) Change in length of diagonal AC. From geometry, 2 2 2 ( ) ( ) ( ) AC AB BC = + Differentiate: 2( ) ( ) 2( ) ( ) 2( ) ( ) AC AC AB AB BC BC Δ = Δ + Δ But ( ) ( ) ( ) AC AB BC AC AB BC δ δ δ Δ = Δ = Δ = Thus, 2( ) 2( ) 2( ) AC AB BC AC AB BC δ δ δ = + 1 1 (10.20 m)+ (2.40 m) 2 2 AC AB BC AB BC AC AC δ δ δ μ μ = + = 8.91 m AC δ μ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.69 The aluminum rod AD is fitted with a jacket that is used to apply a hydrostatic pressure of 6000 psi to the 12-in. portion BC of the rod. Knowing that 6 10.1 10 E = × psi and 0.36, v = determine (a) the change in the total length AD, (b) the change in diameter at the middle of the rod. SOLUTION 6 6 6 6 6000 psi 0 1 ( ) 1 [ 6000 (0.36)(0) (0.36)( 6000)] 10.1 10 380.198 10 1 ( ) 1 [ (0.36)( 6000) 0 (0.36)( 6000)] 10.1 10 427.72 10 x z y x x y z y x y z P v v E v v E σ σ σ ε σ σ σ ε σ σ σ − − = = − = − = = − − = − − − − × = − × = − + − = − − + − − × = × Length subjected to strain : 12 in. x L ε = (a) 6 (12)(427.72 10 ) y y L δ ε − = = × 3 5.13 10 in. l δ − = ×  (b) 6 (1.5)( 380.198 10 ) x x d δ ε − = = − × 3 0.570 10 in. d δ − = − × 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.70 For the rod of Prob. 2.69, determine the forces that should be applied to the ends A and D of the rod (a) if the axial strain in portion BC of the rod is to remain zero as the hydrostatic pressure is applied, (b) if the total length AD of the rod is to remain unchanged. PROBLEM 2.69 The aluminum rod AD is fitted with a jacket that is used to apply a hydrostatic pressure of 6000 psi to the 12-in. portion BC of the rod. Knowing that 6 10.1 10 E = × psi and 0.36, v = determine (a) the change in the total length AD, (b) the change in diameter at the middle of the rod. SOLUTION Over the pressurized portion BC, 1 ( ) ( ) 1 (2 ) x z y y y BC x y z y p v v E vp E σ σ σ σ ε σ σ σ σ = = − = = − + − = + (a) 2 2 2 ( ) 0 2 0 2 (2)(0.36)(6000) 4320 psi (1.5) 1.76715 in 4 4 (1.76715)( 4320) 7630 lb ε σ σ π π σ = + = = − = − = − = = = = = − = − y BC y y y vp vp A d F A i.e., 7630 lb compression  (b) Over unpressurized portions AB and CD, 0 x z σ σ = = ( ) ( ) y y AB y CD E σ ε ε = = For no change in length, ( ) ( ) ( ) 0 ( )( ) ( ) 0 12 (20 12) (2 ) 0 24 (24)(0.36)(6000) 2592 psi 20 20 (1.76715)( 2592) 4580 lb δ ε ε ε ε ε σ σ σ σ = + + = + + = − + + = = − = − = − = = − = − AB y AB BC y BC CD y CD AB CD y AB BC y BC y y y y L L L L L L vp E E vp P A 4580 lb compression P = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.71 In many situations, physical constraints prevent strain from occurring in a given direction. For example, 0 z ε = in the case shown, where longitudinal movement of the long prism is prevented at every point. Plane sections perpendicular to the longitudinal axis remain plane and the same distance apart. Show that for this situation, which is known as plane strain, we can express , z σ , εx and y ε as follows: 2 2 ( ) 1 [(1 ) (1 ) ] 1 [(1 ) (1 ) ] z x y x x y y y x v v v v E v v v E σ σ σ ε σ σ ε σ σ = + = − − + = − − + SOLUTION 1 0 ( ) or ( ) z x y z z x y v v v E ε σ σ σ σ σ σ = = − − + = +  2 2 1 ( ) 1 [ ( )] 1 [(1 ) (1 ) ] x x y z x y x y x y v v E v v E v v v E ε σ σ σ σ σ σ σ σ σ = − − = − − + = − − +  2 2 1 ( ) 1 [ ( )] 1 [(1 ) (1 ) ] y x y z x y x y y x v v E v v E v v v E ε σ σ σ σ σ σ σ σ σ = − + − = − + − + = − − + 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.72 In many situations, it is known that the normal stress in a given direction is zero, for example, 0 z σ = in the case of the thin plate shown. For this case, which is known as plane stress, show that if the strains εx and εy have been determined experimentally, we can express , , σ σ x y and z ε as follows: 2 2 ( ) 1 1 1 x y y x x y z x y v v v E E v v v ε ε ε ε σ σ ε ε ε + + = = = − + − − − SOLUTION 0 1 ( ) z x x y v E σ ε σ σ = = − (1) 1 ( ) y x y v E ε σ σ = − + (2) Multiplying (2) by v and adding to (1), 2 2 1 or ( ) 1 x y x x x y v E v v E v ε ε σ σ ε ε − + = = + −  Multiplying (1) by v and adding to (2), 2 2 1 or ( ) 1 y x y y y x v E v v E v ε ε σ σ ε ε − + = = + −  1 ( ) z x y v v v E E ε σ σ = − − = − E ⋅ 2 2 ( ) 1 (1 ) ( ) ( ) 1 1 x y y x x y x y v v v v v v v v ε ε ε ε ε ε ε ε + + + − + = − + = − + − − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.73 For a member under axial loading, express the normal strain ε′ in a direction forming an angle of 45° with the axis of the load in terms of the axial strain εx by (a) comparing the hypotenuses of the triangles shown in Fig. 2.49, which represent, respectively, an element before and after deformation, (b) using the values of the corresponding stresses of σ′ and σx shown in Fig. 1.38, and the generalized Hooke’s law. SOLUTION Figure 2.49 (a) 2 2 2 2 2 2 2 2 2 2 2 [ 2(1 )] (1 ) (1 ) 2(1 2 ) 1 2 1 2 4 2 2 2 x x x x x x x x x x v v v v v ε ε ε ε ε ε ε ε ε ε ε ε ε ε ε ′ + = + + − ′ ′ + + = + + + − + ′ ′ + = + − + Neglect squares as small 4 2 2 x x v ε ε ε ′ = − 1 2 x v ε ε − ′ =  (A) (B)
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.73 (Continued) (b) 1 2 1 2 x v E E v P E A v E σ σ ε σ ′ ′ ′ = − − = ⋅ − = 1 2 x v ε − = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.74 The homogeneous plate ABCD is subjected to a biaxial loading as shown. It is known that 0 z σ σ = and that the change in length of the plate in the x direction must be zero, that is, 0. x ε = Denoting by E the modulus of elasticity and by v Poisson’s ratio, determine (a) the required magnitude of , x σ (b) the ratio 0 / . z σ ε SOLUTION 0 0 , 0, 0 1 1 ( ) ( ) z y x x x y z x v v v E E σ σ σ ε ε σ σ σ σ σ = = = = − − = − (a) 0 x v σ σ =  (b) 2 2 0 0 0 1 1 1 ( ) ( 0 ) z x y z v v v v E E E ε σ σ σ σ σ σ − = − − + = − − + = 0 2 1 z E v σ ε = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.75 A vibration isolation unit consists of two blocks of hard rubber bonded to a plate AB and to rigid supports as shown. Knowing that a force of magnitude 25 kN P = causes a deflection 1.5 mm δ = of plate AB, determine the modulus of rigidity of the rubber used. SOLUTION 3 3 3 3 1 1 (25 10 N) 12.5 10 N 2 2 12.5 10 N) 833.33 10 Pa (0.15 m)(0.1m) F P F A τ = = × = × × = = = × 3 3 1.5 10 m 0.03 m 1.5 10 0.05 0.03 δ δ γ − − = × = × = = = h h 3 6 833.33 10 16.67 10 Pa 0.05 G τ γ × = = = × 16.67 MPa G = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.76 A vibration isolation unit consists of two blocks of hard rubber with a modulus of rigidity 19 MPa G = bonded to a plate AB and to rigid supports as shown. Denoting by P the magnitude of the force applied to the plate and by δ the corresponding deflection, determine the effective spring constant, / , k P δ = of the system. SOLUTION Shearing strain: h δ γ = Shearing stress: G G h δ τ γ = = Force: 1 2 or 2 GA GA P A P h h δ δ τ = = = Effective spring constant: 2 P GA k h δ = = with 2 (0.15)(0.1) 0.015 m 0.03 m A h = = = 6 2 6 2(19 10 Pa)(0.015 m ) 19.00 10 N/m 0.03 m k × = = × 3 19.00 10 kN/m k = × 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.77 The plastic block shown is bonded to a fixed base and to a horizontal rigid plate to which a force P is applied. Knowing that for the plastic used 55 G = ksi, determine the deflection of the plate when 9 P = kips. SOLUTION Consider the plastic block. The shearing force carried is 3 9 10 lb = × P The area is 2 (3.5)(5.5) 19.25 in = = A Shearing stress: 3 9 10 467.52 psi 19.25 P A τ × = = = Shearing strain: 3 467.52 0.0085006 55 10 τ γ = = = × G But (2.2)(0.0085006) δ γ δ γ = ∴ = = h h 0.0187 in. δ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.78 A vibration isolation unit consists of two blocks of hard rubber bonded to plate AB and to rigid supports as shown. For the type and grade of rubber used all 220 τ = psi and 1800 G = psi. Knowing that a centric vertical force of magnitude 3.2 P = kips must cause a 0.1-in. vertical deflection of the plate AB, determine the smallest allowable dimensions a and b of the block. SOLUTION Consider the rubber block on the right. It carries a shearing force equal to 1 2 . P The shearing stress is 1 2 P A τ = or required area 3 2 3.2 10 7.2727 in 2 (2)(220) τ × = = = P A But (3.0) A b = Hence, 2.42 in. 3.0 = = A b min 2.42 in. = b  Use 2.42 in = b and 220 psi τ = Shearing strain. 220 0.12222 1800 G τ γ = = = But a δ γ = Hence, 0.1 0.818 in. 0.12222 δ γ = = = a min 0.818 in. = a 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.79 The plastic block shown is bonded to a rigid support and to a vertical plate to which a 55-kip load P is applied. Knowing that for the plastic used 150 G = ksi, determine the deflection of the plate. SOLUTION   2 3 3 3 3 3 (3.2)(4.8) 15.36 in 55 10 lb 55 10 3580.7 psi 15.36 150 10 psi 3580.7 23.871 10 150 10 2 in. τ τ γ − = = = × × = = = = × = = = × × = A P P A G G h 3 3 (2)(23.871 10 ) 47.7 10 in. h δ γ − − = = × = × 0.0477 in. δ = ↓ 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.80 What load P should be applied to the plate of Prob. 2.79 to produce a 1 16 -in. deflection? PROBLEM 2.79 The plastic block shown is bonded to a rigid support and to a vertical plate to which a 55-kip load P is applied. Knowing that for the plastic used 150 G = ksi, determine the deflection of the plate. SOLUTION 3 3 1 in. 0.0625 in. 16 2 in. 0.0625 0.03125 2 150 10 psi (150 10 )(0.03125) 4687.5 psi h h G G δ δ γ τ γ = = = = = = = × = = × = 2 3 (3.2)(4.8) 15.36 in (4687.5)(15.36) 72 10 lb τ = = = = = × A P A 72 kips 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.81 Two blocks of rubber with a modulus of rigidity 12 MPa G = are bonded to rigid supports and to a plate AB. Knowing that 100 mm c = and 45 kN, P = determine the smallest allowable dimensions a and b of the blocks if the shearing stress in the rubber is not to exceed 1.4 MPa and the deflection of the plate is to be at least 5 mm. SOLUTION Shearing strain: a G δ τ γ = = 6 6 (12 10 Pa)(0.005 m) 0.0429 m 1.4 10 Pa G a δ τ × = = = × 42.9 mm a =  Shearing stress: 1 2 2 P P A bc τ = = 3 6 45 10 N 0.1607 m 2 2(0.1 m) (1.4 10 Pa) P b cτ × = = = × 160.7 mm b = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.82 Two blocks of rubber with a modulus of rigidity 10 G = MPa are bonded to rigid supports and to a plate AB. Knowing that 200 b = mm and 125 c = mm, determine the largest allowable load P and the smallest allowable thickness a of the blocks if the shearing stress in the rubber is not to exceed 1.5 MPa and the deflection of the plate is to be at least 6 mm. SOLUTION Shearing stress: 1 2 2 P P A bc τ = = 3 2 2(0.2 m)(0.125 m)(1.5 10 kPa) P bcτ = = × P 75.0 kN =  Shearing strain: a G δ τ γ = = 6 6 (10 10 Pa)(0.006 m) 0.04 m 1.5 10 Pa G a δ τ × = = = × 40.0 mm a = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.83∗ Determine the dilatation e and the change in volume of the 200-mm length of the rod shown if (a) the rod is made of steel with 200 E = GPa and 0.30, v = (b) the rod is made of aluminum with 70 E = GPa and 0.35. v = SOLUTION 2 2 2 6 2 3 6 (22) 380.13 mm 380.13 10 m 4 4 46 10 N 121.01 10 Pa 0 1 ( ) (1 2 ) 1 ( ) x y z x x x y z x y z x x x y z x x x A d P P A v v E E v v E v e v v E E π π σ σ σ σ ε σ σ σ σ ε ε ε σ ε ε ε σ σ σ − = = = = × = × = = × = = = − − = = = − = − − = + + = − − = Volume: 2 3 3 (380.13 mm )(200 mm) 76.026 10 mm V AL V Ve = = = × Δ = (a) Steel: 6 6 9 (1 0.60)(121.01 10 ) 242 10 200 10 − − × = = × × e 6 242 10− = × e  3 6 3 (76.026 10 )(242 10 ) 18.40 mm − Δ = × × = V 3 18.40 mm Δ = V  (b) Aluminum: 6 6 9 (1 0.70)(121.01 10 ) 519 10 70 10 − − × = = × × e 6 519 10− = × e  3 6 3 (76.026 10 )(519 10 ) 39.4 mm − Δ = × × = V 3 39.4 mm Δ = V 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.84∗ Determine the change in volume of the 2-in. gage length segment AB in Prob. 2.61 (a) by computing the dilatation of the material, (b) by subtracting the original volume of portion AB from its final volume. SOLUTION From Problem 2.61, thickness = 1 16 in., E = 29 × 106 psi, v = 0.30. (a) 2 1 1 0.03125 in 2 16    = =       A 3 0 0 Volume: (0.03125)(2.00) 0.0625 in = = = V AL 3 3 6 6 6 6 6 600 19.2 10 psi 0 0.03125 1 19.2 10 ( ) 662.07 10 29 10 (0.30)(662.07 10 ) 198.62 10 264.83 10 x y z x x x y z y z x x y z P A v v E E v e σ σ σ σ ε σ σ σ ε ε ε ε ε ε − − − − = = = × = = × = − − = = = × × = = − = − × = − × = + + = × 6 6 3 0 (0.0625)(264.83 10 ) 16.55 10 in − − Δ = = × = × V V e  (b) From the solution to Problem 2.61, 3 6 6 1.324 10 in., 99.3 10 in., 12.41 10 in. δ δ δ − − − = × = − × = − × x y z The dimensions when under a 600-lb tensile load are: 3 0 6 0 6 0 3 6 3 0 Length: 2 1.324 10 2.001324 in. 1 Width: 99.3 10 0.4999007 in. 2 1 Thickness: 12.41 10 0.06248759 in. 16 Volume: 0.062516539 in 0.062516539 0.0625 16.54 10 in δ δ δ − − − − = + = + × = = + = − × = = + = − × = = = Δ = − = − = × x y z L L w w t t V Lwt V V V 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.85∗ A 6-in.-diameter solid steel sphere is lowered into the ocean to a point where the pressure is 7.1 ksi (about 3 miles below the surface). Knowing that 6 29 10 E = × psi and 0.30, v = determine (a) the decrease in diameter of the sphere, (b) the decrease in volume of the sphere, (c) the percent increase in the density of the sphere. SOLUTION For a solid sphere, 3 0 0 3 3 6 (6.00) 6 113.097 in. p π π σ σ σ = = = = = = − x y z V d 3 3 6 6 7.1 10 psi 1 ( ) (1 2 ) (0.4)(7.1 10 ) 29 10 97.93 10 x x y z v v E v p E ε σ σ σ − = − × = − − − × = − = − × = − × Likewise, 6 97.93 10 y z ε ε − = = − × 6 293.79 10 x y z e ε ε ε − = + + = − × (a) 6 6 0 (6.00)( 97.93 10 ) 588 10 in. ε − − −Δ = − = − − × = × x d d 6 588 10 in. − −Δ = × d  (b) 6 3 3 0 (113.097)( 293.79 10 ) 33.2 10 in − − −Δ = − = − − × = × V V e 3 3 33.2 10 in − − Δ = × V  (c) Let mass of sphere. constant. m m = = 0 0 0 (1 ) m V V V e ρ ρ ρ = = = + 0 0 0 0 0 2 3 2 3 6 6 0 0 1 1 1 1 (1 ) 1 (1 ) 1 293.79 10 100% (293.79 10 )(100%) ρ ρ ρ ρ ρ ρ ρ ρ − − − = − = × − = − + + = − + − + − = − + − + ≈ − = × − × = ×   V m V e m e e e e e e e e 0.0294% 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.86∗ (a) For the axial loading shown, determine the change in height and the change in volume of the brass cylinder shown. (b) Solve part a, assuming that the loading is hydrostatic with 70 x y z σ σ σ = = = − MPa. SOLUTION 0 2 2 3 2 3 2 0 0 3 3 6 3 0 0 0 135 mm 0.135 m (85) 5.6745 10 mm 5.6745 10 m 4 4 766.06 10 mm 766.06 10 m h A d V A h π π − − = = = = = × = × = = × = × (a) 6 6 6 9 0, 58 10 Pa, 0 1 58 10 ( ) 552.38 10 105 10 σ σ σ σ ε σ σ σ − = = − × = × = − + − = = − = − × × x y z y y x y z v v E E 6 0 (135 mm)( 552.38 10 ) ε − Δ = = − × y h h 0.0746 mm Δ = − h  6 6 9 (1 2 ) 1 2 (0.34)( 58 10 ) ( ) 187.81 10 105 10 σ σ σ σ − − − − × = + + = = = − × × y x y z v v e E E 3 3 6 0 (766.06 10 mm )( 187.81 10 ) − Δ = = × − × V V e 3 143.9 mm Δ = − V  (b) 6 6 6 6 9 70 10 Pa 210 10 Pa 1 1 2 (0.34)( 70 10 ) ( ) 226.67 10 105 10 σ σ σ σ σ σ ε σ σ σ σ − = = = − × + + = − × − − × = − + − = = = − × × x y z x y z y x y z y v v v E E 6 0 (135 mm)( 226.67 10 ) ε − Δ = = − × y h h 0.0306 mm Δ = − h  6 6 9 1 2 (0.34)( 210 10 ) ( ) 680 10 105 10 σ σ σ − − − × = + + = = − × × x y z v e E 3 3 6 0 (766.06 10 mm )( 680 10 ) − Δ = = × − × V V e 3 521mm Δ = − V 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.87∗ A vibration isolation support consists of a rod A of radius 1 10 R = mm and a tube B of inner radius 2 25 R = mm bonded to an 80-mm-long hollow rubber cylinder with a modulus of rigidity G = 12 MPa. Determine the largest allowable force P that can be applied to rod A if its deflection is not to exceed 2.50 mm. SOLUTION Let r be a radial coordinate. Over the hollow rubber cylinder, 1 2. R r R ≤ ≤ Shearing stress τ acting on a cylindrical surface of radius r is 2 P P A rh τ π = = The shearing strain is 2 P G Ghr τ γ π = = Shearing deformation over radial length dr, 2 d dr P dr d dr Gh r δ γ δ γ π = = = Total deformation. 2 2 1 1 2 1 2 1 2 1 2 1 2 ln (ln ln ) 2 2 2 ln or 2 ln( / ) R R R R R R P dr d Gh r P P r R R Gh Gh R P Gh P Gh R R R δ δ π π π π δ π = = = = − = =   1 2 Data: 10 mm 0.010 m, 25 mm 0.025 m, 80 mm 0.080 m R R h = = = = = = 6 3 6 3 3 12 10 Pa 2.50 10 m (2 )(12 10 )(0.080)(2.50 10 ) 16.46 10 N ln (0.025/0.010) G P δ π − − = × = × × × = = × 16.46 kN 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.88 A vibration isolation support consists of a rod A of radius R1 and a tube B of inner radius R2 bonded to a 80-mm-long hollow rubber cylinder with a modulus of rigidity G = 10.93 MPa. Determine the required value of the ratio R2/R1 if a 10-kN force P is to cause a 2-mm deflection of rod A. SOLUTION Let r be a radial coordinate. Over the hollow rubber cylinder, 1 2. R r R ≤ ≤ Shearing stress τ acting on a cylindrical surface of radius r is 2 P P A rh τ π = = The shearing strain is 2 P G Ghr τ γ π = = Shearing deformation over radial length dr, 2 δ γ δ γ δ π = = = d dr d dr P dr dr Gh r Total deformation. 2 2 1 1 2 1 2 1 2 1 2 ln (ln ln ) 2 2 ln 2 R R R R R R P dr d Gh r P P r R R Gh Gh R P Gh R δ δ π π π π = = = = − =   6 2 3 1 2 1 2 (2 )(10.93 10 )(0.080)(0.002) ln 1.0988 10.10 exp(1.0988) 3.00 R Gh R P R R π δ π × = = = = = 2 1 / 3.00 = R R 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.89∗ The material constants E, G, k, and v are related by Eqs. (2.33) and (2.43). Show that any one of these constants may be expressed in terms of any other two constants. For example, show that (a) k = GE/(9G − 3E) and (b) v = (3k – 2G)/(6k + 2G). SOLUTION and 3(1 2 ) 2(1 ) E E k G v v = = − + (a) 1 or 1 2 2 E E v v G G + = = − 2 2 3[2 2 4 ] 18 6 3 1 2 1 2 = = = − + −     − −         E EG EG k G E G G E E G 9 6 = − EG k G E  (b) 2(1 ) 3(1 2 ) k v G v + = − 3 6 2 2 3 2 2 6 − = + − = + k kv G Gv k G G k 3 2 6 2 − = + k G v k G 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.90∗ Show that for any given material, the ratio G/E of the modulus of rigidity over the modulus of elasticity is always less than 1 2 but more than 1 3 . [Hint: Refer to Eq. (2.43) and to Sec. 2.13.] SOLUTION or 2(1 ) 2(1 ) E E G v v G = = + + Assume 0 v > for almost all materials, and 1 2 < v for a positive bulk modulus. Applying the bounds, 1 2 < 2 1 3 2 E G   ≤ + =     Taking the reciprocals, 1 1 2 3 G E > > or 1 1 3 2 G E < < 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.91∗ A composite cube with 40-mm sides and the properties shown is made with glass polymer fibers aligned in the x direction. The cube is constrained against deformations in the y and z directions and is subjected to a tensile load of 65 kN in the x direction. Determine (a) the change in the length of the cube in the x direction, (b) the stresses , , x y σ σ and . z σ 50 GPa 0.254 15.2 GPa 0.254 15.2 GPa 0.428 x xz y xy z zy E v E v E v = = = = = = SOLUTION Stress-to-strain equations are yx y x zx z x x y z v v E E E σ σ σ ε = − − (1) xy x y zy z y x y z v v E E E σ σ σ ε = − + − (2) yz y xz x z z x y z v v E E E σ σ σ ε = − − + (3) xy yx x y v v E E = (4) yz zy y z v v E E = (5) zx xz z x v v E E = (6) The constraint conditions are 0 and 0. y z ε ε = = Using (2) and (3) with the constraint conditions gives 1 zy xy y z x y z x v v E E E σ σ σ − = (7) 1 yz xz y z x y z x v V E E E σ σ σ − + = (8) 1 0.428 0.254 or 0.428 0.077216 15.2 15.2 50 0.428 1 0.254 or 0.428 0.077216 15.2 15.2 50 y z x y z x y z x y z x σ σ σ σ σ σ σ σ σ σ σ σ − = − = − + = − + =
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.91∗ (Continued) Solving simultaneously, 0.134993 y z x σ σ σ = = Using (4) and (5) in (1), 1 xy xz x x y z x x v v E E E ε σ σ σ = − − 2 6 2 3 6 6 3 6 9 1 [1 (0.254)(0.134993) (0.254)(0.134993)] 0.93142 (40)(40) 1600 mm 1600 10 m 65 10 40.625 10 Pa 1600 10 (0.93142)(40.625 10 ) 756.78 10 50 10 x x x x x x x E E E A P A σ σ σ ε − − − = − − = = = = × × = = = × × × = = × × (a) 6 (40 mm)(756.78 10 ) δ ε − = = × x x x L 0.0303 mm δ = x  (b) 6 40.625 10 Pa σ = × x 40.6 MPa σ = x   6 6 (0.134993)(40.625 10 ) 5.48 10 Pa σ σ = = × = × y z  5.48 MPa σ σ = = y z 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.92∗ The composite cube of Prob. 2.91 is constrained against deformation in the z direction and elongated in the x direction by 0.035 mm due to a tensile load in the x direction. Determine (a) the stresses , , x y σ σ and , z σ (b) the change in the dimension in the y direction. 50 GPa 0.254 15.2 GPa 0.254 15.2 GPa 0.428 x xz y xy z zy E v E v E v = = = = = = SOLUTION yx y x zx z x x y z v v E E E σ σ σ ε = − − (1) xy x y zy z y x y z v v E E E σ σ σ ε = − + − (2) yz y xz x z z x y z v v E E E σ σ σ ε = − − + (3) xy yx x y v v E E = (4) yz zy y z v v E E = (5) zx xz z x v v E E = (6) Constraint condition: 0 Load condition : 0 ε σ = = z y From Equation (3), 1 0 xz x z x z v E E σ σ = − + (0.254)(15.2) 0.077216 50 xz z z x x x v E E σ σ σ = = =
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.92∗ (Continued) From Equation (1) with 0, y σ = 1 1 1 1 [ 0.254 ] [1 (0.254)(0.077216)] 0.98039 0.98039 zx xz x x z x z x z x x x z x x x x x x x x v v E E E E E E E E ε σ σ σ σ σ σ σ σ ε σ = − = − = − = − = = But, 6 0.035 mm 875 10 40 mm x x x L δ ε − = = = × (a) 9 6 3 (50 10 )(875 10 ) 44.625 10 Pa 0.98039 σ − × × = = × x 44.6 MPa σ = x  0 y σ =  6 6 (0.077216)(44.625 10 ) 3.446 10 Pa σ = × = × z 3.45 MPa σ = z  From (2), 6 6 9 9 6 1 (0.254)(44.625 10 ) (0.428)(3.446 10 ) 0 50 10 15.2 10 323.73 10 xy zy y x y z x y z v v E E E ε σ σ σ − = + − × × = − + − × × = − × (b) 6 (40 mm)( 323.73 10 ) δ ε − = = − × y y y L 0.0129 mm δ = − y 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.93 Two holes have been drilled through a long steel bar that is subjected to a centric axial load as shown. For 6.5 P = kips, determine the maximum value of the stress (a) at A, (b) at B. SOLUTION (a) At hole A: 1 1 1 in. 2 2 4 r = ⋅ = 1 3 2.50 in. 2 = − = d 2 net 1 (2.50) 1.25 in 2   = = =     A dt non net 6.5 5.2 ksi 1.25 P A σ = = = ( ) 1 4 2 2 0.1667 3 r D = = From Fig. 2.60a, 2.56 K = max non (2.56)(5.2) σ σ = = K max 13.31ksi σ =  (b) At hole B: 1 (1.5) 0.75, 3 1.5 1.5 in. 2 r d = = = − = 2 net non net 1 6.5 (1.5) 0.75 in , 8.667 ksi 2 0.75 σ   = = = = = =     P A dt A 2 2(0.75) 0.5 3 r D = = From Fig. 2.60a, 2.16 K = max non (2.16)(8.667) σ σ = = K max 18.72 ksi σ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.94 Knowing that all 16 ksi, σ = determine the maximum allowable value of the centric axial load P. SOLUTION At hole A: 1 1 1 in. 2 2 4 = ⋅ = r 1 3 2.50 in. 2 = − = d 2 net 1 (2.50) 1.25 in 2   = = =     A dt ( ) 1 4 2 2 0.1667 3 r D = = From Fig. 2.60a, 2.56 K = net max max net (1.25)(16) 7.81 kips 2.56 KP A P A K σ σ = ∴ = = = At hole B: 1 (1.5) 0.75 in, 3 1.5 1.5 in. 2 = = = − = r d 2 net 1 (1.5) 0.75 in , 2   = = =     A dt 2 2(0.75) 0.5 3 r D = = From Fig. 2.60a, 2.16 K = net max (0.75)(16) 5.56 kips 2.16 A P K σ = = = Smaller value for P controls. 5.56 kips P = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.95 Knowing that the hole has a diameter of 9 mm, determine (a) the radius rf of the fillets for which the same maximum stress occurs at the hole A and at the fillets, (b) the corresponding maximum allowable load P if the allowable stress is 100 MPa. SOLUTION For the circular hole, 1 (9) 4.5 mm 2 r   = =     2 2(4.5) 96 9 87 mm 0.09375 96 r d D = − = = = 6 2 net (0.087 m)(0.009 m) 783 10 m A dt − = = = × From Fig. 2.60a, hole 2.72 K = hole max net K P A σ = 6 6 3 net max hole (783 10 )(100 10 ) 28.787 10 N 2.72 A P K σ − × × = = = × (a) For fillet, 96 mm, 60 mm D d = = 96 1.60 60 D d = = 6 2 min (0.060 m)(0.009 m) 540 10 m A dt − = = = × 6 6 fillet min max max fillet 3 min (5.40 10 )(100 10 ) 28.787 10 1.876 K P A A P K σ σ − × × = = = × = ∴ From Fig. 2.60b, 0.19 0.19 0.19(60) f f r r d d ≈ ∴ ≈ = 11.4 mm f r =  (b) 28.8 kN P = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.96 For 100 kN, P = determine the minimum plate thickness t required if the allowable stress is 125 MPa. SOLUTION At the hole: 20 mm 88 40 48 mm A A r d = = − = 2 2(20) 0.455 88 A A r D = = From Fig. 2.60a, 2.20 K = max net max 3 3 6 (2.20)(100 10 N) 36.7 10 m 36.7 mm (0.048 m)(125 10 Pa) A A KP KP KP t A d t d t σ σ − = = ∴ = × = = × = × At the fillet: 88 88 mm, 64 mm 1.375 64 B B D D d d = = = = 15 15 mm 0.2344 64 B B B r r d = = = From Fig. 2.60b, 1.70 K = max min B KP KP A d t σ = = 3 3 6 max (1.70)(100 10 N) 21.25 10 m 21.25 mm (0.064 m)(125 10 Pa) B KP t d σ − × = = = × = × The larger value is the required minimum plate thickness.  36.7 mm t = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.97 The aluminum test specimen shown is subjected to two equal and opposite centric axial forces of magnitude P. (a) Knowing that E = 70 GPa and all σ = 200 MPa, determine the maximum allowable value of P and the corresponding total elongation of the specimen. (b) Solve part a, assuming that the specimen has been replaced by an aluminum bar of the same length and a uniform 60 × 15-mm rectangular cross section. SOLUTION 6 9 all 2 6 2 min 200 10 Pa 70 10 Pa (60 mm)(15 mm) 900 mm 900 10 m E A σ − = × = × = = = × (a) Test specimen. 75 mm, 60 mm, 6 mm D d r = = = 75 6 1.25 0.10 60 60 D r d d = = = = From Fig. 2.60b max 1.95 P K K A σ = = 6 6 3 max (900 10 )(200 10 ) 92.308 10 N 1.95 A P K σ − × × = = = × 92.3 kN P =  Wide area * 2 3 2 (75 mm)(15 mm) 1125 mm 1.125 10 m A − = = = × 3 9 3 6 3 6 92.308 10 0.150 0.300 0.150 70 10 1.125 10 900 10 1.125 10 7.91 10 m i i i i i i PL L P A E E A δ − − − − ×   = Σ = Σ = + +   × × × ×   = × 0.791 mm δ =  (b) Uniform bar. 6 6 3 all (900 10 )(200 10 ) 180 10 N P Aσ − = = × × = × 180.0 kN P =   3 3 6 9 (180 10 )(0.600) 1.714 10 m (900 10 )(70 10 ) PL AE δ − − × = = = × × ×  1.714 mm δ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.98 For the test specimen of Prob. 2.97, determine the maximum value of the normal stress corresponding to a total elongation of 0.75 mm. PROBLEM 2.97 The aluminum test specimen shown is subjected to two equal and opposite centric axial forces of magnitude P. (a) Knowing that E = 70 GPa and all 200 σ = MPa, determine the maximum allowable value of P and the corresponding total elongation of the specimen. (b) Solve part a, assuming that the specimen has been replaced by an aluminum bar of the same length and a uniform 60 15-mm × rectangular cross section. SOLUTION 3 1 3 2 2 3 2 1 3 2 6 2 2 0.75 10 m 150 mm 0.150 m, 300 mm 0.300 m (75 mm)(15 mm) 1125 mm 1.125 10 m (60 mm)(15 mm) 900 mm 900 10 m i i i i i i PL L P E A E A L L L A A A δ δ − − − = Σ = Σ = × = = = = = = = = = × = = = × 1 3 6 3 9 3 3 0.150 0.300 0.150 600 m 1.125 10 900 10 1.125 10 (70 10 )(0.75 10 ) 87.5 10 N 600 δ − − − − − Σ = + + = × × × × × = = = × Σ i i i i L A E P L A Stress concentration. 75 mm, 60 mm, 6 mm D d r = = = 75 6 1.25 0.10 60 60 D r d d = = = = From Fig. 2.60b 1.95 K = 3 6 max 6 min (1.95)(87.5 10 ) 189.6 10 Pa 900 10 P K A σ − × = = = × × max 189.6 MPa σ =  Note that max all. σ σ < 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.99 A hole is to be drilled in the plate at A. The diameters of the bits available to drill the hole range from 1 2 to 11 /2 in. in 1 4 -in. increments. If the allowable stress in the plate is 21 ksi, determine (a) the diameter d of the largest bit that can be used if the allowable load P at the hole is to exceed that at the fillets, (b) the corresponding allowable load P. SOLUTION At the fillets: 4.6875 0.375 1.5 0.12 3.125 3.125 D r d d = = = = From Fig. 2.60b, 2.10 K = 2 min all max all min min all all (3.125)(0.5) 1.5625 in (1.5625)(21) 15.625 kips 2.10 σ σ σ = = = = = = = A P K A A P K At the hole: net ( 2 ) , from Fig. 2.60 = − A D r t K a net all max all all net σ σ σ = = ∴ = P A K P A K with all 4.6875 in. 0.5 in. 21 ksi D t σ = = = Hole diam. r 2 d D r = − 2 / r D K net A all P 0.5 in. 0.25 in. 4.1875 in. 0.107 2.68 2.0938 in2 16.41 kips 0.75 in. 0.375 in. 3.9375 in. 0.16 2.58 1.96875 in2 16.02 kips 1 in. 0.5 in. 3.6875 in. 0.213 2.49 1.84375 in2 15.55 kips 1.25 in. 0.625 in. 3.4375 in. 0.267 2.41 1.71875 in2 14.98 kips 1.5 in. 0.75 in. 3.1875 in. 0.32 2.34 1.59375 in2 14.30 kips (a) Largest hole with all 15.625 kips P > is the 3 4 -in. diameter hole.  (b) Allowable load all 15.63 kips P = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.100 (a) For 13 kips P = and 1 2 in., d = determine the maximum stress in the plate shown. (b) Solve part a, assuming that the hole at A is not drilled. SOLUTION Maximum stress at hole: Use Fig. 2.60a for values of K. 2 net max net 2 0.5 0.017, 2.68 4.6875 (0.5)(4.6875 0.5) 2.0938 in (2.68)(13) 16.64 ksi, 2.0938 σ = = = = − = = = = r K D A P K A Maximum stress at fillets: Use Fig. 2.60b for values of K. 0.375 4.6875 0.12 1.5 3.125 3.125 r D d d = = = = 2.10 K = 2 min max min (0.5)(3.125) 1.5625 in (2.10)(13) 17.47 ksi 1.5625 σ = = = = = A P K A (a) With hole and fillets: 17.47 ksi  (b) Without hole: 17.47 ksi 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.101 Rod ABC consists of two cylindrical portions AB and BC; it is made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = A force P is applied to the rod and then removed to give it a permanent set 2 p δ = mm. Determine the maximum value of the force P and the maximum amount m δ by which the rod should be stretched to give it the desired permanent set. SOLUTION 2 2 6 2 2 3 2 3 2 6 6 3 max min (30) 706.86 mm 706.86 10 m 4 (40) 1.25664 10 mm 1.25664 10 m 4 (706.86 10 )(250 10 ) 176.715 10 N AB BC Y A A P A π π σ − − − = = = × = = × = × = = × × = × max 176.7 kN P =  3 3 9 6 9 3 3 (176.715 10 )(0.8) (176.715 10 )(1.2) (200 10 )(706.86 10 ) (200 10 )(1.25664 10 ) 1.84375 10 m 1.84375 mm BC AB AB BC P L P L EA EA δ − − − ′ ′ × × ′ = + = + × × × × = × = or 2 1.84375 p m m p δ δ δ δ δ δ ′ ′ = − = + = + 3.84 mm m δ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.102 Rod ABC consists of two cylindrical portions AB and BC; it is made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = A force P is applied to the rod until its end A has moved down by an amount 5 mm. m δ = Determine the maximum value of the force P and the permanent set of the rod after the force has been removed. SOLUTION 2 2 6 2 2 3 2 3 2 6 6 3 max min (30) 706.86 mm 706.86 10 m 4 (40) 1.25664 10 mm 1.25644 10 m 4 (706.86 10 )(250 10 ) 176.715 10 N AB BC Y A A P A π π σ − − − = = = × = = × = × = = × × = × max 176.7 kN P =  3 3 9 6 9 3 3 (176.715 10 )(0.8) (176.715 10 )(1.2) (200 10 )(706.68 10 ) (200 10 )(1.25664 10 ) 1.84375 10 m 1.84375 mm BC AB AB BC P L P L EA EA δ − − − ′ ′ × × ′ = + = + × × × × = × = 5 1.84375 3.16 mm p m δ δ δ′ = − = − = 3.16 mm p δ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.103 The 30-mm square bar AB has a length 2.2 m; L = it is made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 345 MPa. Y σ = A force P is applied to the bar until end A has moved down by an amount . m δ Determine the maximum value of the force P and the permanent set of the bar after the force has been removed, knowing that (a) 4.5 mm, m δ = (b) 8 mm. m δ = SOLUTION 2 6 2 6 3 9 (30)(30) 900 mm 900 10 m (2.2)(345 10 ) 3.795 10 3.795 mm 200 10 Y Y Y A L L E σ δ ε − − = = = × × = = = = × = × If 6 6 3 , (900 10 )(345 10 ) 310.5 10 N δ δ σ − ≥ = = × × = × m Y m Y P A Unloading: 3.795 mm m Y Y P L L AE E σ δ δ ′ = = = = P m δ δ δ′ = − (a) 3 4.5 mm 310.5 10 N δ δ = > = × m Y m P 310.5 kN δ = m  perm 4.5 mm 3.795 mm δ = − perm 0.705 mm δ =  (b) 3 8 mm 310.5 10 N δ δ = > = × m Y m P 310.5 kN δ = m   perm 8.0 mm 3.795 mm δ = − perm 4.205 mm δ = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.104 The 30-mm square bar AB has a length 2.5m; L = it is made of mild steel that is assumed to be elastoplastic with 200 GPa E = and 345 MPa. Y σ = A force P is applied to the bar and then removed to give it a permanent set . p δ Determine the maximum value of the force P and the maximum amount m δ by which the bar should be stretched if the desired value of p δ is (a) 3.5 mm, (b) 6.5 mm. SOLUTION 2 6 2 6 3 9 (30)(30) 900 mm 900 10 m (2.5)(345 10 ) 4.3125 10 m 4.3125 mm 200 10 Y Y Y A L L E σ δ ε − = = = × × = = = = × = × When m δ exceeds , Y δ thus producing a permanent stretch of , p δ the maximum force is 6 6 3 (900 10 )(345 10 ) 310.5 10 N σ − = = × × = × m Y P A 310.5 kN =  δ δ δ δ δ δ δ δ ′ = − = − ∴ = + p m m Y m p Y (a) 3.5 mm 3.5 mm 4.3125 mm δ δ = = + p m 7.81 mm =  (b) 6.5 mm 6.5 mm 4.3125 mm δ δ = = + p m 10.81 mm = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.105 Rod AB is made of a mild steel that is assumed to be elastoplastic with 6 29 10 psi E = × and 36 ksi. Y σ = After the rod has been attached to the rigid lever CD, it is found that end C is 3 8 in. too high. A vertical force Q is then applied at C until this point has moved to position . C′ Determine the required magnitude of Q and the deflection 1 δ if the lever is to snap back to a horizontal position after Q is removed. SOLUTION Since the rod AB is to be stretched permanently, the peak force in the rod is , Y P P = where 2 3 (36) 3.976 kips 4 8 Y Y P A π σ   = = =     Referring to the free body diagram of lever CD, 0: 33 22 0 22 (22)(3.976) 2.65 kips 33 33 Σ = − = = = = D M Q P Q P 2.65 kips = Q  During unloading, the spring back at B is 3 6 (60)(36 10 ) 0.0745 in. 29 10 AB Y B AB Y L L E σ δ ε × = = = = × From the deformation diagram, Slope: 33 0.1117 in. 22 33 22 C B C B δ δ θ δ δ = = ∴ = = − 0.1117 in. δ = C 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.106 Solve Prob. 2.105, assuming that the yield point of the mild steel is 50 ksi. PROBLEM 2.105 Rod AB is made of a mild steel that is assumed to be elastoplastic with 6 29 10 psi E = × and 36 ksi. Y σ = After the rod has been attached to the rigid lever CD, it is found that end C is 3 8 in. too high. A vertical force Q is then applied at C until this point has moved to position C′. Determine the required magnitude of Q and the deflection 1 δ if the lever is to snap back to a horizontal position after Q is removed. SOLUTION Since the rod AB is to be stretched permanently, the peak force in the rod is , Y P P = where 2 3 (50) 5.522 kips 4 8 Y Y P A π σ   = = =     Referring to the free body diagram of lever CD, 0: 33 22 0 D M Q P Σ = − = 22 (22)(5.522) 3.68 kips 33 33 = = = Q P 3.68 kips = Q  During unloading, the spring back at B is 3 6 (60)(50 10 ) 0.1034 in. 29 10 σ δ ε × = = = = × AB Y B AB Y L L E From the deformation diagram, Slope: 33 22 33 22 C B C B δ δ θ δ δ = = ∴ = 0.1552 in. δ = C 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.107 Each cable has a cross-sectional area of 100 mm2 and is made of an elastoplastic material for which 345 MPa Y σ = and 200 GPa. E = A force Q is applied at C to the rigid bar ABC and is gradually increased from 0 to 50 kN and then reduced to zero. Knowing that the cables were initially taut, determine (a) the maximum stress that occurs in cable BD, (b) the maximum deflection of point C, (c) the final displacement of point C. (Hint: In Part c, cable CE is not taut.) SOLUTION Elongation constraints for taut cables. Let rotation angle of rigid bar . θ = ABC CE BD AB AC L L δ δ θ = = 1 2 δ δ δ = = AB BD CE CE AC L L (1) Equilibrium of bar ABC. 0 : 0 A AB BD AC CE AC M L F L F L Q = + − = 1 2 AB CE BD CE BD AC L Q F F F F L = + = + (2) Assume cable CE is yielded. 6 6 3 (100 10 )(345 10 ) 34.5 10 N CE Y F Aσ − = = × × = × From (2), 3 3 3 2( ) (2)(50 10 34.5 10 ) 31.0 10 N BD CE F Q F = − = × − × = × Since 3 < 34.5 10 N, BD Y F Aσ = × cable BD is elastic when 50 kN. Q =
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.107 (Continued) (a) Maximum stresses. 345 MPa CE Y σ σ = = 3 6 6 31.0 10 310 10 Pa 100 10 BD BD F A σ − × = = = × × 310 MPa BD σ =  (b) Maximum of deflection of point C. 3 3 9 6 (31.0 10 )(2) 3.1 10 m (200 10 )(100 10 ) BD BD BD F L EA δ − − × = = = × × × From (1), 3 2 6.2 10 m C CE BD δ δ δ − = = = × 6.20 mm ↓  Permanent elongation of cable CE: ( ) ( ) σ δ δ = − Y CE CE p CE L E max max 6 3 3 9 ( ) ( ) ( ) (345 10 )(2) 6.20 10 2.75 10 m 200 10 CE CE Y CE CE P CE CE F L L EA E σ δ δ δ − − = − = − × = × − = × × (c) Unloading. Cable CE is slack ( 0) CE F = at 0. Q = From (2), 2( ) 2(0 0) 0 BD CE F Q F = − = − = Since cable BD remained elastic, 0. BD BD BD F L EA δ = = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.108 Solve Prob. 2.107, assuming that the cables are replaced by rods of the same cross-sectional area and material. Further assume that the rods are braced so that they can carry compressive forces. PROBLEM 2.107 Each cable has a cross-sectional area of 100 mm2 and is made of an elastoplastic material for which 345 MPa Y σ = and 200 GPa. E = A force Q is applied at C to the rigid bar ABC and is gradually increased from 0 to 50 kN and then reduced to zero. Knowing that the cables were initially taut, determine (a) the maximum stress that occurs in cable BD, (b) the maximum deflection of point C, (c) the final displacement of point C. (Hint: In Part c, cable CE is not taut.) SOLUTION Elongation constraints. Let rotation angle of rigid bar . ABC θ = δ δ θ = = BC CE AB AC L L 1 2 δ δ δ = = AB BD CE CE AC L L (1) Equilibrium of bar ABC. 0: 0 = + − = A AB BD AC CE AC M L F L F L Q 1 2 AB CE BD CE BD AC L Q F F F F L = + = + (2) Assume cable CE is yielded. 6 6 3 (100 10 )(345 10 ) 34.5 10 N CE Y F Aσ − = = × × = × From (2), 3 3 3 2( ) (2)(50 10 34.5 10 ) 31.0 10 N BD CE F Q F = − = × − × = × Since 3 34.5 10 N, BD Y F Aσ < = × cable BD is elastic when 50 kN. Q =
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.108 (Continued) (a) Maximum stresses. 345 MPa CE Y σ σ = = 3 6 6 31.0 10 310 10 Pa 100 10 BD BD F A σ − × = = = × × 310 MPa BD σ =  (b) Maximum of deflection of point C. 3 3 9 6 (31.0 10 )(2) 3.1 10 m (200 10 )(100 10 ) BD BD BD F L EA δ − − × = = = × × × From (1), 3 2 6.2 10 m C CE BD δ δ δ − = = = × 6.20 mm ↓  Unloading. 3 50 10 N, CE C Q δ δ ′ ′ ′ = × = From (1), 1 2 BD C δ δ ′ ′ = Elastic 9 6 1 6 2 (200 10 )(100 10 )( ) 5 10 2 C BD BD C BD EA F L δ δ δ − ′ × × ′ ′′ ′ = = = × 9 6 6 (200 10 )(100 10 )( ) 10 10 2 CE C CE C CE EA F L δ δ δ − ′ ′ × × ′ ′ = = = × From (2), 6 1 2 12.5 10 CE BD C Q F F δ ′ ′ ′ ′ = + = × Equating expressions for , ′ Q 6 3 12.5 10 50 10 C δ ′ × = × 3 4 10 m C δ − ′ = × (c) Final displacement. 3 3 3 ( ) 6.2 10 4 10 2.2 10 m C C m C δ δ δ − − − ′ = − = × − × = × 2.20 mm ↓ 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.109 Rod AB consists of two cylindrical portions AC and BC, each with a cross-sectional area of 1750 mm2 . Portion AC is made of a mild steel with 200 GPa E = and 250 MPa, Y σ = and portion CB is made of a high-strength steel with 200 GPa E = and 345 MPa. Y σ = A load P is applied at C as shown. Assuming both steels to be elastoplastic, determine (a) the maximum deflection of C if P is gradually increased from zero to 975 kN and then reduced back to zero, (b) the maximum stress in each portion of the rod, (c) the permanent deflection of C. SOLUTION Displacement at C to cause yielding of AC. 6 , 3 , , 9 (0.190)(250 10 ) 0.2375 10 m 200 10 σ δ ε − × = = = = × × AC Y AC C Y AC Y AC L L E Corresponding force. 6 6 3 , (1750 10 )(250 10 ) 437.5 10 N σ − = = × × = × AC Y AC F A 9 6 3 3 (200 10 )(1750 10 )(0.2375 10 ) 437.5 10 N 0.190 C CB CB EA F L δ − − × × × = − = − = − × For equilibrium of element at C, 3 ( ) 0 875 10 N AC CB Y Y AC CB F F P P F F − + = = − = × Since applied load 3 3 975 10 N 875 10 N, P = × > × portion AC yields. 3 3 3 437.5 10 975 10 N 537.5 10 N CB AC F F P = − = × − × = − × (a) 3 3 9 6 (537.5 10 )(0.190) 0.29179 10 m (200 10 )(1750 10 ) CB CD C F L EA δ − − × = − = = × × × 0.292 mm  (b) Maximum stresses: , 250 MPa σ σ = = AC Y AC 250 MPa  3 6 6 537.5 10 307.14 10 Pa 307 MPa 1750 10 σ − × = = − = − × = − × BC BC F A 307 MPa −  (c) Deflection and forces for unloading.  3 3 3 3 9 6 975 10 2 487.5 10 N (487.5 10 )(0.190) 0.26464 10 m (200 10 )(1750 10 ) AC AC CB CB AC CB AC AC AB AC CB AC AC P L P L L P P P EA EA L P P P P P δ δ − − ′ ′ ′ ′ ′ ′ = = − ∴ = − = − ′ ′ ′ ′ ′ = × = − = = × × ′ = = × × × 3 3 3 0.29179 10 0.26464 10 0.02715 10 m δ δ δ − − − ′ = − = × − × = × p m 0.0272 mm 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.110 For the composite rod of Prob. 2.109, if P is gradually increased from zero until the deflection of point C reaches a maximum value of 0.3 mm m δ = and then decreased back to zero, determine (a) the maximum value of P, (b) the maximum stress in each portion of the rod, (c) the permanent deflection of C after the load is removed. PROBLEM 2.109 Rod AB consists of two cylindrical portions AC and BC, each with a cross-sectional area of 1750 mm2 . Portion AC is made of a mild steel with 200 E = GPa and 250 MPa, Y σ = and portion CB is made of a high-strength steel with 200 = E GPa and 345 MPa. Y σ = A load P is applied at C as shown. Assuming both steels to be elastoplastic, determine (a) the maximum deflection of C if P is gradually increased from zero to 975 kN and then reduced back to zero, (b) the maximum stress in each portion of the rod, (c) the permanent deflection of C. SOLUTION Displacement at C is 0.30 mm. m δ = The corresponding strains are 3 3 0.30 mm 1.5789 10 190 mm 0.30 mm 1.5789 10 190 mm m AC AC m CB CB L L δ ε δ ε − − = = = × = − = − = − × Strains at initial yielding: 6 , 3 , 9 6 , 3 , 9 250 10 1.25 10 (yielding) 200 10 345 10 1.725 10 (elastic) 200 10 σ ε σ ε − − × = = = × × × = = − = − × × Y AC Y AC Y BC Y CB E E (a) Forces: 6 6 3 (1750 10 )(250 10 ) 437.5 10 N AC Y F Aσ − − = = × × = × 9 6 3 3 (200 10 )(1750 10 )( 1.5789 10 ) 552.6 10 N CB CB F EAε − − − = = × × − × = − × For equilibrium of element at C, 0 AC CB F F P − − = 3 3 3 437.5 10 552.6 10 990.1 10 N = − = × + × = × AC CD P F F 990 kN =  (b) Stresses: , : σ σ = AC Y AC AC 250 MPa =  3 6 6 552.6 10 : 316 10 Pa 1750 10 σ − × = = − = − × × CB CB F CB A 316 MPa − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.110 (Continued) (c) Deflection and forces for unloading. 3 3 3 3 9 6 2 990.1 10 N 495.05 10 N (495.05 10 )(0.190) 0.26874 10 m 0.26874 mm (200 10 )(1750 10 ) AC AC CB CB AC CB AC AC AB AC CB AC AC P L P L L P P P EA EA L P P P P P δ δ − − ′ ′ ′ ′ ′ = = − ∴ = − = − ′ ′ ′ ′ ′ = − = = × ∴ = × × ′ = = × = × × 0.30 mm 0.26874 mm δ δ δ ′ = − = − p m 0.031mm 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.111 Two tempered-steel bars, each 3 16 -in. thick, are bonded to a 1 2 -in. mild-steel bar. This composite bar is subjected as shown to a centric axial load of magnitude P. Both steels are elastoplastic with 6 29 10 E = × and with yield strengths equal to 100 ksi and 50 ksi, respectively, for the tempered and mild steel. The load P is gradually increased from zero until the deformation of the bar reaches a maximum value 0.04 in. m δ = and then decreased back to zero. Determine (a) the maximum value of P, (b) the maximum stress in the tempered-steel bars, (c) the permanent set after the load is removed. SOLUTION For the mild steel, 2 1 1 (2) 1.00 in 2   = =     A 3 1 1 6 (14)(50 10 ) 0.024138 in. 29 10 σ δ × = = = × Y Y L E For the tempered steel, 2 2 3 2 (2) 0.75 in 16   = =     A 3 2 2 3 (14)(100 10 ) 0.048276 in. 29 10 σ δ × = = = × Y Y L E Total area: 2 1 2 1.75 in = + = A A A 1 2. Y m Y δ δ δ < < The mild steel yields. Tempered steel is elastic. (a) Forces: 3 3 1 1 1 (1.00)(50 10 ) 50 10 lb σ = = × = × Y P A 3 3 2 2 (29 10 )(0.75)(0.04) 62.14 10 lb 14 δ × = = = × m EA P L 3 1 2 112.14 10 lb 112.1kips = + = × = P P P 112.1 kips = P  (b) Stresses: 3 1 1 1 1 50 10 psi 50 ksi Y P A σ σ = = = × = 3 3 2 2 2 62.14 10 82.86 10 psi 82.86 ksi 0.75 σ × = = = × = P A 82.86 ksi  Unloading: 3 6 (112.14 10 )(14) 0.03094 in. (29 10 )(1.75) δ × ′ = = = × PL EA (c) Permanent set: 0.04 0.03094 0.00906 in. p m δ δ δ ′ = − = − = 0.00906in. 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.112 For the composite bar of Prob. 2.111, if P is gradually increased from zero to 98 kips and then decreased back to zero, determine (a) the maximum deformation of the bar, (b) the maximum stress in the tempered-steel bars, (c) the permanent set after the load is removed. PROBLEM 2.111 Two tempered-steel bars, each 3 16 -in. thick, are bonded to a 1 2 -in. mild-steel bar. This composite bar is subjected as shown to a centric axial load of magnitude P. Both steels are elastoplastic with 6 29 10 E = × psi and with yield strengths equal to 100 ksi and 50 ksi, respectively, for the tempered and mild steel. SOLUTION Areas: Mild steel: 2 1 1 (2) 1.00 in 2   = =     A Tempered steel: 2 2 3 2 (2) 0.75 in 16   = =     A Total: 2 1 2 1.75 in = + = A A A Total force to yield the mild steel: 3 3 1 1 (1.75)(50 10 ) 87.50 10 lb Y Y Y Y P P A A σ σ = ∴ = = × = × , Y P P > therefore, mild steel yields. Let 1 force carried by mild steel. P = 2 force carried by tempered steel. P = 3 3 1 1 1 (1.00)(50 10 ) 50 10 lb σ = = × = × P A 3 3 3 1 2 2 1 , 98 10 50 10 48 10 lb P P P P P P + = = − = × − × = × (a) 3 2 6 2 (48 10 )(14) (29 10 )(0.75) δ × = = × m P L EA 0.03090in. =  (b) 3 3 2 2 2 48 10 64 10 psi 0.75 σ × = = = × P A 64ksi =  Unloading: 3 6 (98 10 )(14) 0.02703 in. (29 10 )(1.75) δ × ′ = = = × PL EA (c) 0.03090 0.02703 δ δ δ ′ = − = − P m 0.00387in. = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.113 The rigid bar ABC is supported by two links, AD and BE, of uniform 37.5 6-mm × rectangular cross section and made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = The magnitude of the force Q applied at B is gradually increased from zero to 260 kN. Knowing that 0.640 m, a = determine (a) the value of the normal stress in each link, (b) the maximum deflection of point B. SOLUTION Statics: 0: 0.640( ) 2.64 0 C BE AD M Q P P Σ = − − = Deformation: 2.64 , 0.640 A B a δ θ δ θ θ = = = Elastic analysis: 2 6 2 9 6 6 6 6 9 9 6 6 6 6 (37.5)(6) 225 mm 225 10 m (200 10 )(225 10 ) 26.47 10 1.7 (26.47 10 )(2.64 ) 69.88 10 310.6 10 (200 10 )(225 10 ) 45 10 1.0 (45 10 )(0.640 ) 28.80 10 AD A A A AD AD AD BE B B B BE A EA P L P A EA P L δ δ δ θ θ σ θ δ δ δ θ θ σ − − − = = = × × × = = = × = × = × = = × × × = = = × = × = × 9 128 10 BE BE P A θ = = × From Statics, 2.64 4.125 0.640 BE AD BE AD Q P P P P = + = + 6 6 6 [28.80 10 (4.125)(69.88 10 ] 317.06 10 θ θ = × + × = × Y θ at yielding of link AD: 6 9 250 10 310.6 10 AD Y σ σ θ = = × = × 6 6 6 3 804.89 10 (317.06 10 )(804.89 10 ) 255.2 10 N Y Y Q θ − − = × = × × = ×
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.113 (Continued) (a) Since 3 260 10 , Y Q Q = × > link AD yields. 250 MPa AD σ =  6 6 3 (225 10 )(250 10 ) 56.25 10 N AD Y P Aσ − − = = × × = × From Statics, 3 3 4.125 260 10 (4.125)(56.25 10 ) BE AD P Q P = − = × − × 3 3 6 6 27.97 10 N 27.97 10 124.3 10 Pa 225 10 σ − = × × = = = × × BE BE BE P P A 124.3 MPa σ = BE  (b) 3 6 9 6 (27.97 10 )(1.0) 621.53 10 m (200 10 )(225 10 ) BE BE B P L EA δ − − × = = = × × × 0.622 mm B δ = ↓ 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.114 Solve Prob. 2.113, knowing that a = 1.76 m and that the magnitude of the force Q applied at B is gradually increased from zero to 135 kN. PROBLEM 2.113 The rigid bar ABC is supported by two links, AD and BE, of uniform 37.5 6-mm × rectangular cross section and made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = The magnitude of the force Q applied at B is gradually increased from zero to 260 kN. Knowing that 0.640 m, a = determine (a) the value of the normal stress in each link, (b) the maximum deflection of point B. SOLUTION Statics: 0: 1.76( ) 2.64 0 C BE AD M Q P P Σ = − − = Deformation: 2.64 , 1.76 A B δ θ δ θ = = Elastic Analysis: 2 6 2 9 6 6 6 6 9 9 6 6 6 6 (37.5)(6) 225 mm 225 10 m (200 10 )(225 10 ) 26.47 10 1.7 (26.47 10 )(2.64 ) 69.88 10 310.6 10 (200 10 )(225 10 ) 45 10 1.0 (45 10 )(1.76 ) 79.2 10 AD A A A AD AD AD BE B B B BE BE A EA P L P A EA P L δ δ δ θ θ σ θ δ δ δ θ θ σ − − − = = = × × × = = = × = × = × = = × × × = = = × = × = × 9 352 10 BE P A θ = = × From Statics, 2.64 1.500 1.76 BE AD BE AD Q P P P P = + = + 6 6 6 [73.8 10 (1.500)(69.88 10 ] 178.62 10 θ θ = × + × = × Y θ at yielding of link BE: 6 9 250 10 352 10 BE Y Y σ σ θ = = × = × 6 6 6 3 710.23 10 (178.62 10 )(710.23 10 ) 126.86 10 N Y Y Q θ − − = × = × × = × Since 3 135 10 N , Y Q Q = × > link BE yields. 250 MPa BE Y σ σ = =  6 6 3 (225 10 )(250 10 ) 56.25 10 N σ − = = × × = × BE Y P A 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.114 (Continued) From Statics, 3 1 ( ) 52.5 10 N 1.500 AD BE P Q P = − = × (a) 3 6 6 52.5 10 233.3 10 225 10 σ − × = = = × × AD AD P A 233 MPa σ = AD  From elastic analysis of AD, 3 6 751.29 10 rad 69.88 10 θ − = = × × AD P (b) 3 1.76 1.322 10 m B δ θ − = = × 1.322 mm B δ = ↓ 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.115∗ Solve Prob. 2.113, assuming that the magnitude of the force Q applied at B is gradually increased from zero to 260 kN and then decreased back to zero. Knowing that 0.640 m, a = determine (a) the residual stress in each link, (b) the final deflection of point B. Assume that the links are braced so that they can carry compressive forces without buckling. PROBLEM 2.113 The rigid bar ABC is supported by two links, AD and BE, of uniform 37.5 6-mm × rectangular cross section and made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = The magnitude of the force Q applied at B is gradually increased from zero to 260 kN. Knowing that 0.640 m, a = determine (a) the value of the normal stress in each link, (b) the maximum deflection of point B. SOLUTION See solution to Problem 2.113 for the normal stresses in each link and the deflection of Point B after loading. 6 6 6 250 10 Pa 124.3 10 Pa 621.53 10 m AD BE B σ σ δ − = × = × = × The elastic analysis given in the solution to Problem 2.113 applies to the unloading. 6 3 6 6 6 317.06 10 260 10 820.03 10 317.06 10 317.06 10 Q Q Q θ − ′ ′ = × × ′ = = = × × × 9 9 6 6 9 9 6 6 6 310.6 10 (310.6 10 )(820.03 10 ) 254.70 10 Pa 128 10 (128 10 )(820.03 10 ) 104.96 10 Pa 0.640 524.82 10 m AD BE B σ θ σ θ δ θ − − − ′ = × = × × = × ′ = × = × × = × ′ ′ = = × (a) Residual stresses. 6 6 6 , res 250 10 254.70 10 4.70 10 Pa σ σ σ − ′ = − = × − × = − × AD AD AD 4.70MPa = −  6 6 6 , res 124.3 10 104.96 10 19.34 10 Pa σ σ σ ′ = − = × − × = × BE BE BE 19.34 MPa =  (b) 6 6 6 , 621.53 10 524.82 10 96.71 10 m δ δ δ − − − ′ = − = × − × = × B P B B 0.0967 mm = ↓ 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.116 A uniform steel rod of cross-sectional area A is attached to rigid supports and is unstressed at a temperature of 45 F. ° The steel is assumed to be elastoplastic with 36 Y σ = ksi and 6 29 10 psi. E = × Knowing that 6 6.5 10 / F, α − = × ° determine the stress in the bar (a) when the temperature is raised to 320 F, ° (b) after the temperature has returned to 45 F ° . SOLUTION Let P be the compressive force in the rod. Determine temperature change to cause yielding. 3 6 6 ( ) ( ) 0 36 10 ( ) 190.98 F (29 10 )(6.5 10 ) Y Y Y Y L PL L T L T AE E T E σ δ α α σ α − = − + Δ = − + Δ = × Δ = = = ° × × But 320 45 275 F ( ) Y T T Δ = − = ° > Δ (a) Yielding occurs. 36 ksi Y σ σ = − = −  Cooling: 6 6 3 ( T) 275 F ( ) 0 ( ) (29 10 )(6.5 10 )(275) 51.8375 10 psi P T P L L T AE P E T A δ δ δ α σ α − ′ Δ = ° ′ ′ ′ ′ ′ = = = − + Δ = ′ ′ ′ = = − Δ = − × × = − × (b) Residual stress: 3 3 res 36 10 51.8375 10 15.84 10 psi σ σ σ ′ = − − = − × + × = × Y 15.84 ksi 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.117 The steel rod ABC is attached to rigid supports and is unstressed at a temperature of 25 C. ° The steel is assumed elastoplastic, with E = 200 GPa and 250 MPa. y σ = The temperature of both portions of the rod is then raised to 150 C ° . Knowing that α = 6 11.7 10 / C, − × ° determine (a) the stress in both portions of the rod, (b) the deflection of point C. SOLUTION 6 2 6 2 500 10 m 0.150 m 300 10 m 0.250 m − − = × = = × = AC AC CB CB A L A L Constraint: 0 P T δ δ + = Determine ΔT to cause yielding in portion CB. ( ) AC CB AB AC CB AC CB AB AC CB PL PL L T EA EA L L P T L E A A α α − − = Δ   Δ = +     At yielding, 6 6 3 (300 10 )(2.50 10 ) 75 10 N Y CB Y P P A σ − = = = × × = × 3 9 6 6 6 ( ) 75 10 0.150 0.250 90.812 C (0.400)(200 10 )(11.7 10 ) 500 10 300 10 α − − −   Δ = +     ×   = + = °   × × × ×   AC CB Y Y AB AC CB L L P T L E A A Actual ΔT: 150 C 25 C 125 C ( )Y T ° − ° = ° > Δ Yielding occurs. For 3 ( ) , 75 10 N Y Y T T P P Δ > Δ = = × (a) 3 6 6 75 10 150 10 Pa 500 10 Y AC AC P A σ − − × = − = − = − × × 150 MPa AC σ = −  σ σ = − = − Y CB Y CB P A 250 MPa CB σ = −  (b) For ( ) , portion remains elastic. Y T T AC Δ > Δ / 3 6 6 9 6 ( ) (75 10 )(0.150) (0.150)(11.7 10 )(125) 106.9 10 m (200 10 )(500 10 ) Y AC C A AC AC P L L T EA δ α − − − = − + Δ × = − + × = × × × Since Point A is stationary, 6 / 106.9 10 m C C A δ δ − = = × 0.1069 mm C δ = → 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.118∗ Solve Prob. 2.117, assuming that the temperature of the rod is raised to 150°C and then returned to 25 C. ° PROBLEM 2.117 The steel rod ABC is attached to rigid supports and is unstressed at a temperature of 25 C. ° The steel is assumed elastoplastic, with 200 E = GPa and 250 Y σ = MPa. The temperature of both portions of the rod is then raised to 150 C. ° Knowing that 6 11.7 10 / C, α − = × ° determine (a) the stress in both portions of the rod, (b) the deflection of point C. SOLUTION 6 2 6 2 500 10 m 0.150 m 300 10 m 0.250 m − − = × = = × = AC AC CB CB A L A L Constraint: 0 P T δ δ + = Determine ΔT to cause yielding in portion CB. ( ) AC CB AB AC CB AC CB AB AC CB PL PL L T EA EA L L P T L E A A α α − − = Δ   Δ = +     At yielding, 6 6 3 (300 10 )(250 10 ) 75 10 N Y CB Y P P A σ − = = = × × = × 3 9 6 6 6 75 10 0.150 0.250 ( ) (0.400)(200 10 )(11.7 10 ) 500 10 300 10 90.812 C α − − −   ×   Δ = + = +     × × × ×     = ° AC CB Y Y AB AC CB L L P T L E A A Actual : 150 C 25 C 125 C ( ) Δ ° − ° = ° > Δ Y T T Yielding occurs. For 3 ( ) 75 10 N Y Y T T P P Δ > Δ = = × Cooling: ( ) ( ) ( ) 125 C α ′ Δ ′ ′ Δ = ° = + AC CB AC CB AB L L A A EL T T P 6 6 9 6 3 0.150 0.250 500 10 300 10 (200 10 )(0.400)(11.7 10 )(125) 103.235 10 N − − − × × × × = = × + Residual force: 3 3 3 res 103.235 10 75 10 28.235 10 N (tension) ′ = − = × − × = × Y P P P
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.118∗ (Continued) (a) Residual stresses. 3 res 6 28.235 10 500 10 AC AC P A σ − × = = × 56.5 MPa AC σ =  3 res 6 28.235 10 300 10 CB CB P A σ − × = = × 9.41 MPa σ = CB  (b) Permanent deflection of point C. res δ = AC C AC P L EA 0.0424 mm C δ = → 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.119∗ For the composite bar of Prob. 2.111, determine the residual stresses in the tempered-steel bars if P is gradually increased from zero to 98 kips and then decreased back to zero. PROBLEM 2.111 Two tempered-steel bars, each 3 16 -in. thick, are bonded to a 1 2 -in. mild-steel bar. This composite bar is subjected as shown to a centric axial load of magnitude P. Both steels are elastoplastic with 6 29 10 E = × psi and with yield strengths equal to 100 ksi and 50 ksi, respectively, for the tempered and mild steel. The load P is gradually increased from zero until the deformation of the bar reaches a maximum value 0.04 m δ = in. and then decreased back to zero. Determine (a) the maximum value of P, (b) the maximum stress in the tempered-steel bars, (c) the permanent set after the load is removed. SOLUTION Areas: Mild steel: 2 1 1 (2) 1.00 in 2   = =     A Tempered steel: 2 2 3 (2) (2) 0.75 in 16   = =     A Total: 2 1 2 1.75 in = + = A A A Total force to yield the mild steel: 3 3 1 1 (1.75)(50 10 ) 87.50 10 lb σ σ = ∴ = = × = × Y Y Y Y P P A A P > PY; therefore, mild steel yields. Let 1 2 3 3 1 1 1 3 3 3 1 2 2 1 3 3 2 2 2 force carried by mild steel. force carried by tempered steel. (1.00)(50 10 ) 50 10 lb , 98 10 50 10 48 10 lb 48 10 64 10 psi 0.75 σ σ = = = = × = × + = = − = × − × = × × = = = × Y P P P A P P P P P P P A Unloading: 3 3 98 10 56 10 psi 1.75 P A σ × ′ = = = × Residual stresses. Mild steel: 3 3 3 1,res 1 50 10 56 10 6 10 psi σ σ σ − ′ = − = × − × = − × 6 ksi = − Tempered steel: 3 3 3 2,res 2 1 64 10 56 10 8 10 psi σ σ σ = − = × − × = × 8.00 ksi 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.120∗ For the composite bar in Prob. 2.111, determine the residual stresses in the tempered-steel bars if P is gradually increased from zero until the deformation of the bar reaches a maximum value 0.04 m δ = in. and is then decreased back to zero. PROBLEM 2.111 Two tempered-steel bars, each 3 16 -in. thick, are bonded to a 1 2 -in. mild-steel bar. This composite bar is subjected as shown to a centric axial load of magnitude P. Both steels are elastoplastic with 6 29 10 E = × psi and with yield strengths equal to 100 ksi and 50 ksi, respectively, for the tempered and mild steel. The load P is gradually increased from zero until the deformation of the bar reaches a maximum value 0.04 m δ = in. and then decreased back to zero. Determine (a) the maximum value of P, (b) the maximum stress in the tempered-steel bars, (c) the permanent set after the load is removed. SOLUTION For the mild steel, 3 2 1 1 1 6 1 (14)(50 10 ) (2) 1.00 in 0.024138 in 2 29 10 δ δ ×   = = = = =   ×   Y Y L A E For the tempered steel, 3 2 2 2 2 6 3 (14)(100 10 ) 2 (2) 0.75 in 0.048276 in. 16 29 10 δ δ ×   = = = = =   ×   Y Y L A E Total area: 2 1 2 1.75 in = + = A A A 1 2 δ δ δ < < Y m Y The mild steel yields. Tempered steel is elastic. Forces: 3 3 1 1 1 6 3 2 2 (1.00)(50 10 ) 50 10 lb (29 10 )(0.75)(0.04) 62.14 10 lb 14 δ δ = = × = × × = = = × Y m P A EA P L Stresses: 3 3 3 1 2 1 1 2 1 2 62.14 10 50 10 psi 82.86 10 psi 0.75 σ δ σ × = = = × = = = × Y P P A A Unloading: 3 112.14 64.08 10 psi 1.75 P A σ′ = = = × Residual stresses. 3 3 3 1,res 1 50 10 64.08 10 14.08 10 psi 14.08 ksi σ σ σ ′ = − = × − × = − × = − 3 3 3 2,res 2 82.86 10 64.08 10 18.78 10 psi 18.78 ksi σ σ σ ′ = − = × − × = × = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.121∗ Narrow bars of aluminum are bonded to the two sides of a thick steel plate as shown. Initially, at 1 70 F, T = ° all stresses are zero. Knowing that the temperature will be slowly raised to T2 and then reduced to T1, determine (a) the highest temperature T2 that does not result in residual stresses, (b) the temperature T2 that will result in a residual stress in the aluminum equal to 58 ksi. Assume 6 12.8 10 / F α − = × ° a for the aluminum and 6 6.5 10 / F α − = × ° s for the steel. Further assume that the aluminum is elastoplastic, with E 6 10.9 10 = × psi and 58 Y σ = ksi. (Hint: Neglect the small stresses in the plate.) SOLUTION Determine temperature change to cause yielding. 3 6 6 ( ) ( ) ( )( ) 58 10 ( ) 844.62 F ( ) (10.9 10 )(12.8 6.5)(10 ) a Y s Y a s Y Y Y Y a s PL L T L T EA P E T A T E δ α α σ α α σ σ α α − = + Δ = Δ = = − − Δ = − × Δ = = = ° − × − (a) 2 1 ( ) 70 844.62 915 F = + Δ = + = ° Y Y T T T 915 F °  After yielding, ( ) ( ) Y a s L L T L T E σ δ α α = + Δ = Δ Cooling: ( ) ( ) a s P L L T L T AE δ α α ′ ′ ′ ′ = + Δ = Δ The residual stress is res ( )( ) Y Y a s P E T A σ σ σ α α ′ = − = − − Δ Set res ( )( ) Y Y Y a s E T σ σ σ σ α α = − − = − − Δ 3 6 6 2 (2)(58 10 ) 1689 F ( ) (10.9 10 )(12.8 6.5)(10 ) σ α α − × Δ = = = ° − × − Y a s T E (b) 2 1 70 1689 1759 F = + Δ = + = ° T T T 1759 F °  If 2 1759 F, T > ° the aluminum bar will most likely yield in compression.
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.122∗ Bar AB has a cross-sectional area of 1200 mm2 and is made of a steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = Knowing that the force F increases from 0 to 520 kN and then decreases to zero, determine (a) the permanent deflection of point C, (b) the residual stress in the bar. SOLUTION 2 6 2 1200 mm 1200 10 m A − = = × Force to yield portion AC: 6 6 3 (1200 10 )(250 10 ) 300 10 N AC Y P Aσ − = = × × = × For equilibrium, 0. + − = CB AC F P P 3 3 3 300 10 520 10 220 10 N = − = × − × = − × CB AC P P F 3 9 6 3 3 6 6 (220 10 )(0.440 0.120) (200 10 )(1200 10 ) 0.293333 10 m 220 10 1200 10 183.333 10 Pa δ σ − − − × − = − = × × = × × = = × = − × CB CB C CB CB P L EA P A
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.122∗ (Continued) Unloading: ( ) δ ′ ′ ′ − ′ = = − =   ′ + =     AC AC CB CB AC CB C AC BC CB AC P L P L F P L EA EA EA L L FL P EA EA EA 3 3 3 3 3 3 6 6 3 6 6 (520 10 )(0.440 0.120) 378.182 10 N 0.440 378.182 10 520 10 141.818 10 N 378.182 10 315.152 10 Pa 1200 10 141.818 10 118.182 10 Pa 1200 10 (3 σ σ δ − − × − ′ = = = × + ′ ′ = − = × − × = − × ′ × ′ = = = × × ′ × ′ = = − = − × × ′ = CB AC AC CB CB AC AC AC BC BC C FL P L L P P F P A P A 3 9 6 78.182)(0.120) 0.189091 10 m (200 10 )(1200 10 ) − = × × × (a) 3 3 3 , 0.293333 10 0.189091 10 0.1042 10 m δ δ δ − − − ′ = − = × − × = × C p C C 0.1042 mm =  (b) 6 6 6 , res 250 10 315.152 10 65.2 10 Pa σ σ σ′ = − = × − × = − × AC Y AC 65.2 MPa = −  6 6 6 , res 183.333 10 118.182 10 65.2 10 Pa σ σ σ′ = − = − × + × = − × CB CB CB 65.2 MPa = − 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.123∗ Solve Prob. 2.122, assuming that 180 a = mm. PROBLEM 2.122 Bar AB has a cross-sectional area of 1200 mm2 and is made of a steel that is assumed to be elastoplastic with 200 E = GPa and 250 Y σ = MPa. Knowing that the force F increases from 0 to 520 kN and then decreases to zero, determine (a) the permanent deflection of point C, (b) the residual stress in the bar. SOLUTION 2 6 2 1200 mm 1200 10 m A − = = × Force to yield portion AC: 6 6 3 (1200 10 )(250 10 ) 300 10 N AC Y P Aσ − = = × × = × For equilibrium, 0. + − = CB AC F P P 3 3 3 300 10 520 10 220 10 N CB AC P P F = − = × − × = − × 3 9 6 3 3 6 6 (220 10 )(0.440 0.180) (200 10 )(1200 10 ) 0.238333 10 m 220 10 1200 10 183.333 10 Pa δ σ − − − × − = − = × × = × × = = − × = − × CB CB C CB CB P L EA P A
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.123∗ (Continued) Unloading: ( ) AC AC CB CB AC CB C AC BC CB AC P L P L F P L EA EA EA L L FL P EA EA EA δ ′ ′ ′ − ′ = = − =   ′ = + =     3 3 3 3 3 3 3 9 6 3 6 (520 10 )(0.440 0.180) 307.273 10 N 0.440 307.273 10 520 10 212.727 10 N (307.273 10 )(0.180) 0.230455 10 m (200 10 )(1200 10 ) 307.273 10 256.061 1200 10 CB AC AC CB CB AC C AC AC FL P L L P P F P A δ σ − − − × − ′ = = = × + ′ ′ = − = × − × = − × × ′ = = × × × ′ × ′ = = = × 6 3 6 6 10 Pa 212.727 10 177.273 10 P 1200 10 CB CB P A σ − × ′ − × ′ = = = − × × (a) 3 3 3 , 0.238333 10 0.230455 10 0.00788 10 m δ δ δ − − − ′ = − = × − × = × C p C C 0.00788 mm =  (b) 6 6 6 ,res 250 10 256.061 10 6.06 10 Pa AC AC AC σ σ σ′ = − = × − × = − × 6.06 MPa = −  6 6 6 ,res 183.333 10 177.273 10 6.06 10 Pa CB CB CB σ σ σ′ = − = − × + × = − × 6.06 MPa = −  
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.124 Rod BD is made of steel 6 ( 29 10 psi) E = × and is used to brace the axially compressed member ABC. The maximum force that can be developed in member BD is 0.02P. If the stress must not exceed 18 ksi and the maximum change in length of BD must not exceed 0.001 times the length of ABC, determine the smallest-diameter rod that can be used for member BD. SOLUTION 3 0.02 (0.02)(130) 2.6 kips 2.6 10 lb = = = = × BD F P Considering stress: 3 18 ksi 18 10 psi σ = = × 2 2.6 0.14444 in 18 σ σ = ∴ = = = BD BD F F A A Considering deformation: (0.001)(144) 0.144 in. δ = = 3 2 6 (2.6 10 )(54) 0.03362 in (29 10 )(0.144) δ δ × = ∴ = = = × BD BD BD BD F L F L A AE E Larger area governs. 2 0.14444 in = A 2 4 (4)(0.14444) 4 π π π = ∴ = = A A d d 0.429in. = d 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.125 Two solid cylindrical rods are joined at B and loaded as shown. Rod AB is made of steel ( 200 GPa) E = and rod BC of brass ( 105 GPa). E = Determine (a) the total deformation of the composite rod ABC, (b) the deflection of point B. SOLUTION Rod AB: 3 30 10 N AB F P = − = − × 9 2 2 6 2 3 6 9 6 0.250 m 200 10 GPa (30) 706.85 mm 706.85 10 m 4 (30 10 )(0.250) 53.052 10 m (200 10 )(706.85 10 ) π δ − − − = = × = = = × × = = − = − × × × AB AB AB AB AB AB AB AB L E A F L E A Rod BC: 3 30 40 70 kN 70 10 N BC F = + = = × 9 2 3 2 3 2 3 6 9 3 0.300 m 105 10 Pa (50) 1.9635 10 mm 1.9635 10 m 4 (70 10 )(0.300) 101.859 10 m (105 10 )(1.9635 10 ) π δ − − − = = × = = × = × × = = − = − × × × BC BC BC BC BC BC BC BC L E A F L E A (a) Total deformation: 6 tot 154.9 10 m δ δ δ − = + = − × AB BC 0.1549 mm = −  (b) Deflection of Point B. B BC δ δ = 0.1019 mm B δ = ↓ 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.126 Two solid cylindrical rods are joined at B and loaded as shown. Rod AB is made of steel 6 ( 29 10 = × E psi), and rod BC of brass 6 ( 15 10 psi). E = × Determine (a) the total deformation of the composite rod ABC, (b) the deflection of point B. SOLUTION Portion AB: 3 2 2 2 6 3 3 6 40 10 lb 40 in. 2 in. (2) 3.1416 in 4 4 29 10 psi (40 10 )(40) 17.5619 10 in. (29 10 )(3.1416) AB AB AB AB AB AB AB AB AB P L d A d E P L E A π π δ − = × = = = = = = × × = = = × × Portion BC: 3 2 2 2 6 3 3 6 20 10 lb 30 in. 3 in. (3) 7.0686 in 4 4 15 10 psi ( 20 10 )(30) 5.6588 10 in. (15 10 )(7.0686) BC BC BC BC BC BC BC BC BC P L d A d E P L E A π π δ − = − × = = = = = = × − × = = = − × × (a) 6 6 17.5619 10 5.6588 10 AB BC δ δ δ − − = + = × − × 3 11.90 10 in. δ − = × ↓  (b) B BC δ δ = − 3 5.66 10 in. B δ − = × ↑ 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.127 The uniform wire ABC, of unstretched length 2l, is attached to the supports shown and a vertical load P is applied at the midpoint B. Denoting by A the cross-sectional area of the wire and by E the modulus of elasticity, show that, for , l δ  the deflection at the midpoint B is 3 δ = P l AE SOLUTION Use approximation. sin tan l δ θ θ ≈ ≈ Statics: 0 : 2 sin 0 θ Σ = − = Y AB F P P 2sin 2 θ δ = ≈ AB P Pl P Elongation: 2 2 AB AB P l Pl AE AE δ δ = = Deflection: From the right triangle, 2 2 2 2 2 ( ) AB l l l δ δ δ + = + = 2 2 2 AB AB l l δ δ + + − 3 1 2 1 2 2 AB AB AB l l l Pl AE δ δ δ δ   = + ≈     ≈ 3 3 3 Pl P l AE AE δ δ ≈ ∴ ≈ 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.128 The brass strip AB has been attached to a fixed support at A and rests on a rough support at B. Knowing that the coefficient of friction is 0.60 between the strip and the support at B, determine the decrease in temperature for which slipping will impend. SOLUTION Brass strip: 6 105 GPa 20 10 / C E α − = = × ° 0: 0 Σ = − = = y F N W N W 0: 0 ( ) 0 μ μ μ μ δ α α α Σ = − = = = = − + Δ = Δ = = x F P N P W mg PL P mg L T T EA EA EA Data: 2 6 2 2 9 0.60 (20)(3) 60 mm 60 10 m 100 kg 9.81 m/s 105 10 Pa A m g E μ − = = = = × = = = × 9 6 6 (0.60)(100)(9.81) (105 10 )(60 10 )(20 10 ) T − Δ = × × × 4.67 C T Δ = ° 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.129 Members AB and CD are 1 8 1 -in.-diameter steel rods, and members BC and AD are 7 8 -in.-diameter steel rods. When the turnbuckle is tightened, the diagonal member AC is put in tension. Knowing that 6 29 10 E = × psi and 4 = h ft, determine the largest allowable tension in AC so that the deformations in members AB and CD do not exceed 0.04 in. SOLUTION 2 2 2 6 3 0.04 in. 4ft 48 in. (1.125) 0.99402 in 4 4 (29 10 )(0.99402)(0.04) 24.022 10 lb 48 AB CD CD CD CD CD CD CD CD CD CD CD h L A d F L EA EA F L δ δ π π δ δ = = = = = = = = = × = = = × Use joint C as a free body. 4 5 0: 0 5 4 Σ = − = ∴ = y CD AC AC CD F F F F F 3 3 5 (24.022 10 ) 30.0 10 lb 4 = × = × AC F 30.0 kips = AC F 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.130 The 1.5-m concrete post is reinforced with six steel bars, each with a 28-mm diameter. Knowing that 200 s E = GPa and 25 c E = GPa, determine the normal stresses in the steel and in the concrete when a 1550-kN axial centric force P is applied to the post. SOLUTION Let portion of axial force carried by concrete. portion carried by the six steel rods. = = c s P P ( ) c c c c c c s s s s s s c s c c s s c c s s P L E A P E A L P L E A P E A L P P P E A E A L P L E A E A δ δ δ δ δ δ ε = = = = = + = + − = = + 2 2 3 2 3 2 2 2 3 3 2 3 2 3 6 9 3 9 3 6 6 (28) 3.6945 10 mm 4 4 3.6945 10 m (450) 3.6945 10 4 4 155.349 10 mm 153.349 10 m 1.5 m 1550 10 335.31 10 (25 10 )(155.349 10 ) (200 10 )(3.6945 10 ) s s c c s A d A d A L π π π π ε − − − − − = = = × = × = − = − × = × = × = × = = × × × + × × 9 6 6 (200 10 )(335.31 10 ) 67.1 10 Pa σ ε − = = × × = × s s E σs = 67.1 MPa  9 6 6 (25 10 )( 335.31 10 ) 8.38 10 Pa σ ε − = = × − × = × c c E σc = 8.38 MPa 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.131 The brass shell 6 ( 11.6 10 / F) α − = × ° b is fully bonded to the steel core 6 ( 6.5 10 / F). α − = × ° s Determine the largest allowable increase in temperature if the stress in the steel core is not to exceed 8 ksi. SOLUTION Let axial force developed in the steel core. s P = For equilibrium with zero total force, the compressive force in the brass shell is . s P Strains: ( ) ( ) s s s s s s b b b b P T E A P T E A ε α ε α = + Δ = − + Δ Matching: s b ε ε = ( ) ( ) s s s b s s b b P P T T E A E A α α + Δ = − + Δ 1 1 ( )( ) s b s s s b b P T E A E A α α   + = − Δ     (1) 2 2 (1.5)(1.5) (1.0)(1.0) 1.25 in (1.0)(1.0) 1.0 in = − = = = b s A A 6 3 3 5.1 10 / F (8 10 )(1.0) 8 10 lb b s s s s P A α α σ − − = × ° = = × = × 9 1 6 6 1 1 1 1 87.816 10 lb (29 10 )(1.0) (15 10 )(1.25) s s b b E A E A − − + = + = × × × From (1), 9 3 6 (87.816 10 )(8 10 ) (5.1 10 )( ) T − − × × = × Δ 137.8 F Δ = ° T 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.132 A fabric used in air-inflated structures is subjected to a biaxial loading that results in normal stresses 120 x σ = MPa and 160 z σ = MPa. Knowing that the properties of the fabric can be approximated as E = 87 GPa and v = 0.34, determine the change in length of (a) side AB, (b) side BC, (c) diagonal AC. SOLUTION 6 6 6 6 6 9 6 6 3 9 120 10 Pa, 0, 160 10 Pa 1 1 ( ) [120 10 (0.34)(160 10 )] 754.02 10 87 10 1 1 ( ) [ (0.34)(120 10 ) 160 10 ] 1.3701 10 87 10 σ σ σ ε σ σ σ ε σ σ σ − − = × = = × = − − = × − × = × × = − − + = − × + × = × × x y z x x y z z x y z v v E v v E (a) 6 ( ) (100 mm)(754.02 10 ) δ ε − = = × AB x AB 0.0754 mm =  (b) 6 ( ) (75 mm)(1.3701 10 ) δ ε − = = × BC z BC 0.1028 mm =  Label sides of right triangle ABC as a, b, and c. 2 2 2 c a b = + Obtain differentials by calculus. 2 2 2 = + = + c dc a da b db a b dc da db c c But 2 2 100 mm, 75 mm, (100 75 ) 125 mm 0.0754 mm 0.1370 mm δ δ = = = + = = = = = AB BC a b c da db (c) 100 75 (0.0754) (0.1028) 125 125 δ = = + AC dc 0.1220 mm = 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.133 An elastomeric bearing ( 0.9 G = MPa) is used to support a bridge girder as shown to provide flexibility during earthquakes. The beam must not displace more than 10 mm when a 22-kN lateral load is applied as shown. Knowing that the maximum allowable shearing stress is 420 kPa, determine (a) the smallest allowable dimension b, (b) the smallest required thickness a. SOLUTION Shearing force: 3 22 10 N P = × Shearing stress: 3 420 10 Pa τ = × 3 3 2 3 3 2 22 10 52.381 10 m 420 10 52.381 10 mm (200 mm)( ) P P A A A b τ τ − = ∴ = × = = × × = × = (a) 3 52.381 10 262 mm 200 200 A b × = = = 262 mm = b  3 3 6 420 10 466.67 10 0.9 10 G τ γ − × = = = × × (b) But 3 10 mm 21.4 mm 466.67 10 a a δ δ γ γ − = ∴ = = = × 21.4 mm = a 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.134 Knowing that 10 kips, P = determine the maximum stress when (a) 0.50 in., = r (b) 0.625 in. r = SOLUTION 3 10 10 lb 5.0 in. 2.50 in. 5.0 2.00 2.50 P D d D d = × = = = = 2 min 3 (2.50) 1.875 in 4 A dt   = = =     (a) 0.50 0.50 in. 0.20 2.50 r r d = = = From Fig. 2.60b, 1.94 K = 3 3 max min (1.94)(10 10 ) 10.35 10 psi 1.875 KP A σ × = = = × 10.35 ksi  (b) 3 3 max min 0.625 0.625 in. 0.25 1.82 2.50 (1.82)(10 10 ) 9.71 10 psi 1.875 r r K d KP A σ = = = = × = = = × 9.71 ksi 
PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.135 The uniform rod BC has a cross-sectional area A and is made of a mild steel that can be assumed to be elastoplastic with a modulus of elasticity E and a yield strength . y σ Using the block-and-spring system shown, it is desired to simulate the deflection of end C of the rod as the axial force P is gradually applied and removed, that is, the deflection of points C and C′ should be the same for all values of P. Denoting by μ the coefficient of friction between the block and the horizontal surface, derive an expression for (a) the required mass m of the block, (b) the required constant k of the spring. SOLUTION Force-deflection diagram for Point C or rod BC. For max σ δ δ σ < = = = = = Y Y C C Y Y P P A PL EA P EA L P P A Force-deflection diagram for Point C′ of block-and-spring system. 0 : 0 Σ = − = = y F N mg N mg 0: 0 Σ = − = = x f f F P F P F If block does not move, i.e., or , μ μ μ < = < f F N mg P mg then or c c P P k K δ δ ′ ′ = = If P = μ mg, then slip at occurs. μ = = m P F mg If the force P is the removed, the spring returns to its initial length. (a) Equating PY and Fmax, σ σ μ μ = = Y Y A A mg m g  (b) Equating slopes, EA k L = 

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Chapter02.pdf

  • 3. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.1 An 80-m-long wire of 5-mm diameter is made of a steel with 200 GPa E = and an ultimate tensile strength of 400 MPa. If a factor of safety of 3.2 is desired, determine (a) the largest allowable tension in the wire, (b) the corresponding elongation of the wire. SOLUTION (a) 6 2 2 2 6 2 400 10 Pa (5) 19.635 mm 19.635 10 m 4 4 U A d π π σ − = × = = = = × 6 6 all (400 10 )(19.635 10 ) 7854 N 7854 2454 N . 3.2 U U U P A P P F S σ − = = × × = = = = all 2.45 kN = P  (b) 3 6 9 (2454)(80) 50.0 10 m (19.635 10 )(200 10 ) PL AE δ − − = = = × × × 50.0 mm δ = 
  • 4. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.2 A steel control rod is 5.5 ft long and must not stretch more than 0.04 in. when a 2-kip tensile load is applied to it. Knowing that 6 29 10 psi, E = × determine (a) the smallest diameter rod that should be used, (b) the corresponding normal stress caused by the load. SOLUTION (a) 6 (2000 lb)(5.5 12 in.) 0.04 in. (29 10 psi) : PL AE A δ × = = × 2 2 1 0.11379 in 4 π = = A d 0.38063 in. d = 0.381 in. d =  (b) 2 2000 lb 17580 psi 0.11379 in σ = = = P A 17.58 ksi σ = 
  • 5. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.3 Two gage marks are placed exactly 10 in. apart on a 1 2 -in.-diameter aluminum rod with 6 10.1 10 E = × psi and an ultimate strength of 16 ksi. Knowing that the distance between the gage marks is 10.009 in. after a load is applied, determine (a) the stress in the rod, (b) the factor of safety. SOLUTION (a) 10.009 10.000 0.009 in. δ = − = 6 3 (10.1 10 )(0.009) 9.09 10 psi 10 E L E L δ σ δ ε σ × = = = = = × 9.09 ksi σ =  (b) 16 . . 9.09 σ σ = = U F S . . 1.760 = F S 
  • 6. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.4 An 18-m-long steel wire of 5-mm diameter is to be used in the manufacture of a prestressed concrete beam. It is observed that the wire stretches 45 mm when a tensile force P is applied. Knowing that 200 GPa, E = determine (a) the magnitude of the force P, (b) the corresponding normal stress in the wire. SOLUTION (a) , or PL AE P AE L δ δ = = with 2 2 6 2 1 1 (0.005) 19.6350 10 m 4 4 A d π π − = = = × 6 2 9 2 (0.045 m)(19.6350 10 m )(200 10 N/m ) 9817.5 N 18 m P − × × = = 9.82 kN P =  (b) 6 6 2 9817.5 N 500 10 Pa 19.6350 10 m P A σ − = = = × × 500 MPa σ = 
  • 7. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.5 A polystyrene rod of length 12 in. and diameter 0.5 in. is subjected to an 800-lb tensile load. Knowing that E 6 0.45 10 psi, = × determine (a) the elongation of the rod, (b) the normal stress in the rod. SOLUTION 2 2 2 (0.5) 0.19635 in 4 4 π π = = = A d (a) 6 (800)(12) 0.1086 (0.19635)(0.45 10 ) PL AE δ = = = × 0.1086 in. δ =  (b) 800 4074 psi 0.19635 P A σ = = = 4.07 ksi σ = 
  • 8. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.6 A nylon thread is subjected to a 8.5-N tension force. Knowing that 3.3 GPa = E and that the length of the thread increases by 1.1%, determine (a) the diameter of the thread, (b) the stress in the thread. SOLUTION (a) Strain: 1.1 0.011 100 L δ ε = = = Stress: 9 6 (3.3 10 )(0.011) 36.3 10 Pa E σ ε = = × = × P A σ = Area: 9 2 6 8.5 234.16 10 m 36.3 10 P A σ − = = = × × Diameter: 9 6 4 (4)(234.16 10 ) 546 10 m A d π π − − × = = = × 0.546 mm d =  (b) Stress: 36.3 MPa σ = 
  • 9. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.7 Two gage marks are placed exactly 250 mm apart on a 12-mm-diameter aluminum rod. Knowing that, with an axial load of 6000 N acting on the rod, the distance between the gage marks is 250.18 mm, determine the modulus of elasticity of the aluminum used in the rod. SOLUTION 0 0 2 2 2 6 2 6 6 250.18 250.00 0.18 mm 0.18 mm 0.00072 250 mm (12) 113.097mm 113.097 10 m 4 4 6000 53.052 10 Pa 113.097 10 δ δ ε π π σ − − = Δ = − = − = = = = = = = = × = = = × × L L L L A d P A  6 9 53.052 10 73.683 10 Pa 0.00072 E σ ε × = = = × 73.7 GPa E = 
  • 10. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.8 An aluminum pipe must not stretch more than 0.05 in. when it is subjected to a tensile load. Knowing that 6 10.1 10 E = × psi and that the maximum allowable normal stress is 14 ksi, determine (a) the maximum allowable length of the pipe, (b) the required area of the pipe if the tensile load is 127.5 kips. SOLUTION (a) ; PL AE δ = Thus, 6 3 (10.1 10 )(0.05) 14 10 EA E L P δ δ σ × = = = × 36.1 in. = L  (b) ; P A σ = Thus, 3 3 127.5 10 14 10 P A σ × = = × 2 9.11 in = A 
  • 11. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.9 An aluminum control rod must stretch 0.08 in. when a 500-lb tensile load is applied to it. Knowing that all 22 σ = ksi and 6 10.1 10 E = × psi, determine the smallest diameter and shortest length that can be selected for the rod. SOLUTION 3 all 2 all 3 all 2 500 lb, 0.08 in. 22 10 psi 500 0.022727 in 22 10 4 (4)(0.022727) 4 P P P A A A A d d δ σ σ σ σ π π π = = = × = < > = = × = = = min 0.1701 in. = d  all 6 3 all (10.1 10 )(0.08) 36.7 in. 22 10 E E L E L δ σ ε σ δ σ = = < × > = = × min 36.7 in. = L 
  • 12. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.10 A square yellow-brass bar must not stretch more than 2.5 mm when it is subjected to a tensile load. Knowing that 105 E = GPa and that the allowable tensile strength is 180 MPa, determine (a) the maximum allowable length of the bar, (b) the required dimensions of the cross section if the tensile load is 40 kN. SOLUTION 6 3 9 3 180 10 Pa 40 10 N 105 10 Pa 2.5 10 m P E σ δ − = × = × = × = × (a) 9 3 6 (105 10 )(2.5 10 ) 1.45833 m 180 10 PL L AE E E L σ δ δ σ − = = × × = = = × 1.458 m L =  (b) 3 6 2 2 6 40 10 222.22 10 m 222.22 mm 180 10 P A P A σ σ − = × = = = × = × 2 222.22 A a a A = = = 14.91 mm a = 
  • 13. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.11 A 4-m-long steel rod must not stretch more than 3 mm and the normal stress must not exceed 150 MPa when the rod is subjected to a 10-kN axial load. Knowing that 200 GPa, E = determine the required diameter of the rod. SOLUTION 4 m L = 3 6 9 3 3 10 m, 150 10 Pa 200 10 Pa, 10 10 N E P δ σ − = × = × = × = × Stress: 3 6 2 2 6 10 10 66.667 10 m 66.667 mm 150 10 P A P A σ σ − = × = = = × = × Deformation: 3 6 2 2 9 3 (10 10 )(4) 66.667 10 m 66.667 mm (200 10 )(3 10 ) PL AE PL A E δ δ − − = × = = = × = × × The larger value of A governs: 2 66.667 mm A = 2 4 4(66.667) 4 A A d d π π π = = = 9.21 mm d = 
  • 14. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.12 A nylon thread is to be subjected to a 10-N tension. Knowing that 3.2 E = GPa, that the maximum allowable normal stress is 40 MPa, and that the length of the thread must not increase by more than 1%, determine the required diameter of the thread. SOLUTION Stress criterion: 6 9 2 6 9 2 6 40 MPa 40 10 Pa 10 N 10 N : 250 10 m 40 10 Pa 250 10 : 2 2 564.19 10 m 4 P P P A A A A d d σ σ σ π π π − − − = = × = = = = = × × × = = = = × 0.564 mm d = Elongation criterion: 1% 0.01 : L PL AE δ δ = = = 9 9 2 9 6 2 / 10 N/3.2 10 Pa 312.5 10 m / 0.01 312.5 10 2 2 630.78 10 m P E A L A d δ π π − − − × = = = × × = = = × 0.631 mm d = The required diameter is the larger value: 0.631 mm d = 
  • 15. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.13 The 4-mm-diameter cable BC is made of a steel with 200 GPa. = E Knowing that the maximum stress in the cable must not exceed 190 MPa and that the elongation of the cable must not exceed 6 mm, find the maximum load P that can be applied as shown. SOLUTION 2 2 6 4 7.2111 m = + = BC L Use bar AB as a free body. 4 0: 3.5 (6) 0 7.2111 0.9509   Σ = − =     = A BC BC M P F P F Considering allowable stress: 6 190 10 Pa σ = × 2 2 6 2 6 6 3 (0.004) 12.566 10 m 4 4 (190 10 )(12.566 10 ) 2.388 10 N π π σ σ − − = = = × = ∴ = = × × = × BC BC A d F F A A Considering allowable elongation: 3 6 10 m δ − = × 6 9 3 3 (12.566 10 )(200 10 )(6 10 ) 2.091 10 N 7.2111 BC BC BC BC F L AE F AE L δ δ − − × × × = ∴ = = = × Smaller value governs. 3 2.091 10 N BC F = × 3 3 0.9509 (0.9509)(2.091 10 ) 1.988 10 N BC P F = = × = × 1.988 kN P = 
  • 16. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.14 The aluminum rod ABC ( 6 10.1 10 psi), E = × which consists of two cylindrical portions AB and BC, is to be replaced with a cylindrical steel rod DE ( 6 29 10 psi) E = × of the same overall length. Determine the minimum required diameter d of the steel rod if its vertical deformation is not to exceed the deformation of the aluminum rod under the same load and if the allowable stress in the steel rod is not to exceed 24 ksi. SOLUTION Deformation of aluminum rod. 3 6 2 2 4 4 28 10 12 18 10.1 10 (1.5) (2.25) 0.031376 in. BC AB A AB BC BC AB AB BC PL PL A E A E L L P E A A π π δ = +   = +       × = +     ×   = Steel rod. 0.031376 in. δ = 3 2 6 3 2 3 (28 10 )(30) 0.92317 in (29 10 )(0.031376) 28 10 1.1667 in 24 10 δ δ σ σ × = ∴ = = = × × = ∴ = = = × PL PL A EA E P P A A Required area is the larger value. 2 1.1667 in = A Diameter: 4 (4)(1.6667) A d π π = = 1.219 in. = d 
  • 17. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.15 A 4-ft section of aluminum pipe of cross-sectional area 1.75 in2 rests on a fixed support at A. The 5 8 -in.-diameter steel rod BC hangs from a rigid bar that rests on the top of the pipe at B. Knowing that the modulus of elasticity is 6 29 10 × psi for steel, and 6 10.4 10 × psi for aluminum, determine the deflection of point C when a 15-kip force is applied at C. SOLUTION Rod BC: 6 7 ft 84 in. 29 10 psi BC BC L E = = = × 2 2 2 3 / 6 (0.625) 0.30680 in 4 4 (15 10 )(84) 0.141618 in. (29 10 )(0.30680) π π δ = = = × = = = × BC BC C B BC BC A d PL E A Pipe AB: 6 4 ft 48 in. 10.4 10 psi AB AB L E = = = × 2 3 3 / 6 1.75 in (15 10 )(48) 39.560 10 in. (10.4 10 )(1.75) δ − = × = = = × × AB AB B A AB AB A PL E A Total: 3 / / 39.560 10 0.141618 0.181178 in. δ δ δ − = + = × + = C B A C B 0.1812 in. C δ = 
  • 18. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.16 The brass tube ( 105 GPa) = AB E has a cross-sectional area of 140 mm2 and is fitted with a plug at A. The tube is attached at B to a rigid plate that is itself attached at C to the bottom of an aluminum cylinder ( 72 GPa) E = with a cross-sectional area of 250 mm2 . The cylinder is then hung from a support at D. In order to close the cylinder, the plug must move down through 1 mm. Determine the force P that must be applied to the cylinder. SOLUTION Shortening of brass tube AB: 2 6 2 9 9 9 6 375 1 376 mm 0.376 m 140 mm 140 10 m 105 10 Pa (0.376) 25.578 10 (105 10 )(140 10 ) δ − − − = + = = = = × = × = = = × × × AB AB AB AB AB AB AB L A E PL P P E A Lengthening of aluminum cylinder CD: 2 6 2 9 9 9 6 0.375 m 250 mm 250 10 m 72 10 Pa (0.375) 20.833 10 (72 10 )(250 10 ) δ − − − = = = × = × = = = × × × CD CD CD CD CD CD CD L A E PL P P E A Total deflection: A AB CD δ δ δ = + where 0.001 m A δ = 9 9 0.001 (25.578 10 20.833 10 ) − − = × + × P 3 21.547 10 N P = × 21.5 kN P = 
  • 19. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.17 A 250-mm-long aluminum tube ( 70 GPa) E = of 36-mm outer diameter and 28-mm inner diameter can be closed at both ends by means of single-threaded screw-on covers of 1.5-mm pitch. With one cover screwed on tight, a solid brass rod ( 105 GPa) E = of 25-mm diameter is placed inside the tube and the second cover is screwed on. Since the rod is slightly longer than the tube, it is observed that the cover must be forced against the rod by rotating it one-quarter of a turn before it can be tightly closed. Determine (a) the average normal stress in the tube and in the rod, (b) the deformations of the tube and of the rod. SOLUTION 2 2 2 2 2 6 2 tube 2 2 2 6 2 rod 9 tube 9 6 tube tube rod 6 rod rod ( ) (36 28 ) 402.12 mm 402.12 10 m 4 4 (25) 490.87 mm 490.87 10 m 4 4 (0.250) 8.8815 10 (70 10 )(402.12 10 ) (0.250) (105 10 )(490.87 1 o i A d d A d PL P P E A PL P E A π π π π δ δ − − − − = − = − = = × = = = = × = = = × × × = − = × × 9 6 * 6 * * tube rod tube rod 9 9 6 3 3 9 4.8505 10 0 ) 1 turn 1.5 mm 0.375 mm 375 10 m 4 or 8.8815 10 4.8505 10 375 10 0.375 10 27.308 10 N (8.8815 4.8505)(10 ) P P P P δ δ δ δ δ δ δ − − − − − − − − = − ×   = × = = ×     = + − = × + × = × × = = × + (a) 3 6 tube 6 tube 27.308 10 67.9 10 Pa 402.12 10 σ − × = = = × × P A tube 67.9 MPa σ =  3 6 rod 6 rod 27.308 10 55.6 10 Pa 490.87 10 σ − × = − = − = − × × P A rod 55.6 MPa σ = −  (b) 9 3 6 tube (8.8815 10 )(27.308 10 ) 242.5 10 m δ − − = × × = × tube 0.2425 mm δ =  9 3 6 rod (4.8505 10 )(27.308 10 ) 132.5 10 m δ − − = − × × = − × rod 0.1325 mm δ = − 
  • 20. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.18 The specimen shown is made from a 1-in.-diameter cylindrical steel rod with two 1.5-in.-outer-diameter sleeves bonded to the rod as shown. Knowing that 6 29 10 psi, = × E determine (a) the load P so that the total deformation is 0.002 in., (b) the corresponding deformation of the central portion BC. SOLUTION (a) i i i i i i PL L P A E E A δ = Σ = Σ 1 2 4 i i i i L P E A d A π δ −   = Σ =     L, in. d, in. A, in2 L/A, in–1 AB 2 1.5 1.7671 1.1318 BC 3 1.0 0.7854 3.8197 CD 2 1.5 1.7671 1.1318 6.083 ← sum 6 1 3 (29 10 )(0.002)(6.083) 9.353 10 lb P − = × = × 9.53 kips P =  (b) 3 6 9.535 10 (3.8197) 29 10 BC BC BC BC BC PL L P A E E A δ × = = = × 3 1.254 10 in. δ − = × 
  • 21. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.19 Both portions of the rod ABC are made of an aluminum for which 70 GPa. E = Knowing that the magnitude of P is 4 kN, determine (a) the value of Q so that the deflection at A is zero, (b) the corresponding deflection of B. SOLUTION (a) 2 2 6 2 (0.020) 314.16 10 m 4 4 AB AB A d π π − = = = × 2 2 3 2 (0.060) 2.8274 10 m 4 4 BC BC A d π π − = = = × Force in member AB is P tension. Elongation: 3 6 9 6 (4 10 )(0.4) 72.756 10 m (70 10 )(314.16 10 ) δ − − × = = = × × × AB AB AB PL EA Force in member BC is Q − P compression. Shortening: 9 9 3 ( ) ( )(0.5) 2.5263 10 ( ) (70 10 )(2.8274 10 ) δ − − − − = = = × − × × BC BC BC Q P L Q P Q P EA For zero deflection at A, BC AB δ δ = 9 6 3 2.5263 10 ( ) 72.756 10 28.8 10 N − − × − = × ∴ − = × Q P Q P 3 3 3 28.3 10 4 10 32.8 10 N Q = × + × = × 32.8 kN = Q  (b) 6 72.756 10 m AB BC B δ δ δ − = = = × 0.0728 mm δ = ↓ AB 
  • 22. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.20 The rod ABC is made of an aluminum for which 70 GPa. E = Knowing that 6 kN = P and 42 kN, = Q determine the deflection of (a) point A, (b) point B. SOLUTION 2 2 6 2 2 2 3 2 (0.020) 314.16 10 m 4 4 (0.060) 2.8274 10 m 4 4 AB AB BC BC A d A d π π π π − − = = = × = = = × 3 3 3 3 6 10 N 6 10 42 10 36 10 N 0.4 m 0.5 m = = × = − = × − × = − × = = AB BC AB BC P P P P Q L L 3 6 6 9 3 6 3 9 (6 10 )(0.4) 109.135 10 m (314.16 10 )(70 10 ) ( 36 10 )(0.5) 90.947 10 m (2.8274 10 )(70 10 ) AB AB AB AB A BC BC BC BC P L A E P L A E δ δ − − − − × = = = × × × − × = = = − × × × (a) 6 6 6 109.135 10 90.947 10 m 18.19 10 m A AB BC δ δ δ − − − = + = × − × = × 0.01819 mm A δ = ↑  (b) 6 90.9 10 m 0.0909 mm B BC δ δ − = = − × = − or 0.0919 mm B δ = ↓ 
  • 23. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.21 Members AB and BC are made of steel 6 ( 29 10 psi) E = × with cross- sectional areas of 0.80 in2 and 0.64 in2 , respectively. For the loading shown, determine the elongation of (a) member AB, (b) member BC. SOLUTION (a) 2 2 6 5 7.810 ft 93.72 in. = + = = AB L Use joint A as a free body. 3 5 0: 28 0 7.810 43.74 kip 43.74 10 lb Σ = − = = = × y AB AB F F F 3 6 (43.74 10 )(93.72) (29 10 )(0.80) δ × = = × AB AB AB AB F L EA 0.1767 in. δ = AB  (b) Use joint B as a free body. 3 6 0: 0 7.810 (6)(43.74) 33.60 kip 33.60 10 lb. 7.810 Σ = − = = = = × x BC AB BC F F F F 3 6 (33.60 10 )(72) (29 10 )(0.64) δ × = = × BC BC BC BC F L EA 0.1304 in. BC δ = 
  • 24. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.22 The steel frame ( 200 GPa) E = shown has a diagonal brace BD with an area of 1920 mm2 . Determine the largest allowable load P if the change in length of member BD is not to exceed 1.6 mm. SOLUTION 3 2 6 2 2 2 9 9 6 3 3 1.6 10 m, 1920 mm 1920 10 m 5 6 7.810 m, 200 10 Pa (200 10 )(1920 10 )(1.6 10 ) 7.81 78.67 10 N δ δ δ − − − − = × = = × = + = = × = × × × = = = × BD BD BD BD BD BD BD BD BD BD BD BD BD BD A L E F L E A E A F L Use joint B as a free body. 0: x F Σ = 5 0 7.810 − = BD F P 3 3 5 (5)(78.67 10 ) 7.810 7.810 50.4 10 N × = = = × BD P F 50.4 kN = P 
  • 25. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.23 For the steel truss ( 200 GPa) E = and loading shown, determine the deformations of the members AB and AD, knowing that their cross-sectional areas are 2400 mm2 and 1800 mm2 , respectively. SOLUTION Statics: Reactions are 114 kN upward at A and C. Member BD is a zero force member. 2 2 4.0 2.5 4.717 m = + = AB L Use joint A as a free body. 2.5 0: 114 0 4.717 y AB F F Σ = + = 215.10 kN AB F = − 4 0: 0 4.717 x AD AB F F F Σ = + = (4)( 215.10) 182.4 kN 4.717 AD F − = − = Member AB: 3 9 6 ( 215.10 10 )(4.717) (200 10 )(2400 10 ) AB AB AB AB F L EA δ − − × = = × × 3 2.11 10 m − = − × 2.11 mm δ − AB  Member AD: 3 9 6 (182.4 10 )(4.0) (200 10 )(1800 10 ) AD AD AD AD F L EA δ − × = = × × 3 2.03 10 m − = × 2.03 mm δ = AD 
  • 26. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.24 For the steel truss 6 ( 29 10 psi) E = × and loading shown, determine the deformations of the members BD and DE, knowing that their cross- sectional areas are 2 in2 and 3 in2 , respectively. SOLUTION Free body: Portion ABC of truss 0 : (15 ft) (30 kips)(8 ft) (30 kips)(16 ft) 0 48.0 kips E BD BD M F F Σ = − − = = + Free body: Portion ABEC of truss 0: 30 kips 30 kips 0 60.0 kips Σ = + − = = + x DE DE F F F  3 2 6 ( 48.0 10 lb)(8 12 in.) (2 in )(29 10 psi) δ + × × = = × BD PL AE 3 79.4 10 in. δ − = + × BD   3 2 6 ( 60.0 10 lb)(15 12 in.) (3 in )(29 10 psi) δ + × × = = × DE PL AE 3 124.1 10 in. δ − + × DE 
  • 27. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.25 Each of the links AB and CD is made of aluminum 6 ( 10.9 10 psi) E = × and has a cross-sectional area of 0.2 in.2 . Knowing that they support the rigid member BC, determine the deflection of point E. SOLUTION Free body BC: 3 0: (32) (22)(1 10 ) 0 687.5 lb C AB AB M F F Σ = − + × = = 3 0: 687.5 1 10 0 312.5 lb y CD CD F F F Σ = − × + = = 3 6 3 6 (687.5)(18) 5.6766 10 in (10.9 10 )(0.2) (312.5)(18) 2.5803 10 in (10.9 10 )(0.2) δ δ δ δ − − = = = × = × = = = × = × AB AB AB B CD CD CD C F L EA F L EA Deformation diagram: 3 6 3.0963 10 Slope 32 96.759 10 rad δ δ θ − − − × = = = × B C BC L 3 6 3 2.5803 10 (22)(96.759 10 ) 4.7090 10 in δ δ θ − − − = + = × + × = × E C EC L 3 4.71 10 in δ − = × ↓ E 
  • 28. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.26 The length of the 3 32 -in.-diameter steel wire CD has been adjusted so that with no load applied, a gap of 1 16 in. exists between the end B of the rigid beam ACB and a contact point E. Knowing that 6 29 10 psi, E = × determine where a 50-lb block should be placed on the beam in order to cause contact between B and E. SOLUTION Rigid beam ACB rotates through angle θ to close gap. 3 1/16 3.125 10 rad 20 θ − = = × Point C moves downward. 3 3 3 2 2 3 2 4 4(3.125 10 ) 12.5 10 in. 12.5 10 in. 3 6.9029 10 in 4 32 C CD C CD CD CD CD CD A d d F L EA δ θ δ δ π π δ − − − − = = × = × = = ×   = = = ×     = 6 3 3 (29 10 )(6.9029 10 )(12.5 10 ) 12.5 200.18 lb CD CD CD CD EA F L δ − − × × × = = = Free body ACB: 0: 4 (50)(20 ) 0 A CD M F x Σ = − − = (4)(200.18) 20 16.0144 50 3.9856 in. x x − = = = For contact, 3.99 in. x < 
  • 29. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.27 Link BD is made of brass ( 105 GPa) E = and has a cross-sectional area of 240 mm2 . Link CE is made of aluminum ( 72 GPa) E = and has a cross- sectional area of 300 mm2 . Knowing that they support rigid member ABC determine the maximum force P that can be applied vertically at point A if the deflection of A is not to exceed 0.35 mm. SOLUTION Free body member AC: 0: 0.350 0.225 0 1.55556 Σ = − = = C BD BD M P F F P 0: 0.125 0.225 0 0.55556 Σ = − = = B CE CE M P F F P 9 9 6 9 9 6 (1.55556 )(0.225) 13.8889 10 (105 10 )(240 10 ) (0.55556 )(0.150) 3.8581 10 (72 10 )(300 10 ) δ δ δ δ − − − − = = = = × × × = = = = × × × BD BD B BD BD BD CE CE C CE CE CE F L P P E A F L P P E A Deformation Diagram: From the deformation diagram, Slope, 9 9 17.7470 10 78.876 10 0.225 B C BC P P L δ δ θ − − + × = = = × 9 9 9 13.8889 10 (0.125)(78.876 10 ) 23.748 10 δ δ θ − − − = + = × + × = × A B AB L P P P Apply displacement limit. 3 9 0.35 10 m 23.748 10 δ − − = × = × A P 3 14.7381 10 N P = × 14.74 kN P = 
  • 30. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.28 Each of the four vertical links connecting the two rigid horizontal members is made of aluminum ( 70 GPa) = E and has a uniform rectangular cross section of 10 × 40 mm. For the loading shown, determine the deflection of (a) point E, (b) point F, (c) point G. SOLUTION Statics. Free body EFG. 3 0 : (400)(2 ) (250)(24) 0 7.5 kN 7.5 10 N F BE BE M F F Σ = − − = = − = − × 3 0 : (400)(2 ) (650)(24) 0 19.5 kN 19.5 10 N E CF CF M F F Σ = − = = = × Area of one link: 2 6 2 (10)(40) 400 mm 400 10 m − = = = × A Length: 300 mm 0.300 m = = L Deformations. 3 6 9 6 3 6 9 6 ( 7.5 10 )(0.300) 80.357 10 m (70 10 )(400 10 ) (19.5 10 )(0.300) 208.93 10 m (70 10 )(400 10 ) BE BE CF CF F L EA F L EA δ δ − − − − − × = = = − × × × × = = = × × ×
  • 31. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.28 (Continued) (a) Deflection of Point E. | | δ δ = E BF 80.4 m δ μ = ↑ E  (b) Deflection of Point F. F CF δ δ = 209 m F δ μ = ↓  Geometry change. Let θ be the small change in slope angle. 6 6 6 80.357 10 208.93 10 723.22 10 radians 0.400 δ δ θ − − − + × + × = = = × E F EF L (c) Deflection of Point G. G F FG L δ δ θ = + 6 6 6 208.93 10 (0.250)(723.22 10 ) 389.73 10 m δ δ θ − − − = + = × + × = × G F FG L 390 m δ μ = ↓ G 
  • 32. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.29 A vertical load P is applied at the center A of the upper section of a homogeneous frustum of a circular cone of height h, minimum radius a, and maximum radius b. Denoting by E the modulus of elasticity of the material and neglecting the effect of its weight, determine the deflection of point A. SOLUTION Extend the slant sides of the cone to meet at a point O and place the origin of the coordinate system there. From geometry, tan b a h α − = 1 1 , , tan tan tan α α α = = = a b a b r y At coordinate point y, 2 A r π = Deformation of element of height dy: δ = Pdy d AE 2 2 2 tan δ π π α = = P dy P dy d E r E y Total deformation. 1 1 1 1 2 2 2 2 1 1 1 1 1 tan tan tan b b A a a P dy P P y a b E y E E δ π α π α π α     = = − = −          1 1 1 1 2 1 1 ( ) tan b a P b a P a b Eab E π π α − − = = A Ph Eab δ π = ↓ 
  • 33. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.30 A homogeneous cable of length L and uniform cross section is suspended from one end. (a) Denoting by ρ the density (mass per unit volume) of the cable and by E its modulus of elasticity, determine the elongation of the cable due to its own weight. (b) Show that the same elongation would be obtained if the cable were horizontal and if a force equal to half of its weight were applied at each end. SOLUTION (a) For element at point identified by coordinate y, 2 0 0 weight of portion below the point ( ) ( ) ( ) ( ) 1 2 L L P g A L y Pdy gA L y dy g L y d dy EA EA E g L y g dy Ly y E E ρ ρ ρ δ ρ ρ δ = = − − − = = = −   = = −      2 2 2 ρ   = −       g L L E 2 1 2 ρ δ = gL E  (b) Total weight: ρ = W gAL 2 1 1 2 2 δ ρ ρ = = ⋅ = EA EA gL F gAL L L E 1 2 F W = 
  • 34. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.31 The volume of a tensile specimen is essentially constant while plastic deformation occurs. If the initial diameter of the specimen is d1, show that when the diameter is d, the true strain is 1 2ln( / ). ε = t d d SOLUTION If the volume is constant, 2 2 1 0 4 4 d L d L π π = 2 2 1 1 2 0 2 1 0 ln ln ε   = =       = =     t d d L L d d d L L d 1 2ln ε = t d d 
  • 35. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.32 Denoting by ε the “engineering strain” in a tensile specimen, show that the true strain is ln (1 ). ε ε = + t SOLUTION 0 0 0 0 ln ln ln 1 ln (1 ) δ δ ε ε   + = = = + = +     t L L L L L Thus ln(1 ) ε ε = + t 
  • 36. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.33 An axial force of 200 kN is applied to the assembly shown by means of rigid end plates. Determine (a) the normal stress in the aluminum shell, (b) the corresponding deformation of the assembly. SOLUTION Let Pa = Portion of axial force carried by shell Pb = Portion of axial force carried by core. , or a a a a a a P L E A P E A L δ δ = = , or b b b b b b P L E A P E A L δ δ = = Thus, ( ) a b a a b b P P P E A E A L δ = + = + with 2 2 3 2 2 3 2 [(0.060) (0.025) ] 2.3366 10 m 4 (0.025) 0.49087 10 m 4 a b A A π π − − = − = × = = × 9 3 9 3 6 [(70 10 )(2.3366 10 ) (105 10 )(0.49087 10 )] 215.10 10 P L P L δ δ − − = × × + × × = × Strain: 3 3 6 6 200 10 0.92980 10 215.10 10 215.10 10 δ ε − × = = = = × × × P L (a) 9 3 6 (70 10 )(0.92980 10 ) 65.1 10 Pa σ ε − = = × × = × a a E 65.1 MPa a σ =  (b) 3 (0.92980 10 )(300 mm) L δ ε − = = × 0.279 mm δ = 
  • 37. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.34 The length of the assembly shown decreases by 0.40 mm when an axial force is applied by means of rigid end plates. Determine (a) the magnitude of the applied force, (b) the corresponding stress in the brass core. SOLUTION Let Pa = Portion of axial force carried by shell and Pb = Portion of axial force carried by core. , or a a a a a a P L E A P E A L δ δ = = , or b b b b b b P L E A P E A L δ δ = = Thus, ( ) a b a a b b P P P E A E A L δ = + = + with 2 2 3 2 2 3 2 [(0.060) (0.025) ] 2.3366 10 m 4 (0.025) 0.49087 10 m 4 a b A A π π − − = − = × = = × 9 3 9 3 6 [(70 10 )(2.3366 10 ) (105 10 )(0.49087 10 )] 215.10 10 δ δ − − = × × + × × = × P L L with 0.40 mm, 300 mm L δ = = (a) 6 3 0.40 (215.10 10 ) 286.8 10 N 300 P = × = × 287 kN P =  (b) 9 3 6 3 (105 10 )(0.40 10 ) 140 10 Pa 300 10 δ σ − − × × = = = = × × b b b b P E A L 140.0MPa σ = b 
  • 38. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.35 A 4-ft concrete post is reinforced with four steel bars, each with a 3 4 -in. diameter. Knowing that 6 29 10 s E = × psi and 6 3.6 10 c E = × psi, determine the normal stresses in the steel and in the concrete when a 150-kip axial centric force P is applied to the post. SOLUTION 2 2 3 4 1.76715 in 4 4 π     = =           s A 2 2 8 62.233 in = − = c s A A 6 s 6 (48) 0.93663 10 (1.76715)(29 10 ) s s s s s P L P P A E δ − = = = × × 6 c 6 (48) 0.21425 10 (62.233)(3.6 10 ) c c c c c P L P P A E δ − = = = × × But : s c δ δ = 6 6 0.93663 10 0.21425 10 s c P P − − × = × 0.22875 s c P P = (1) Also: 150 kips s c P P P + = = (2) Substituting (1) into (2): 1.22875 150 kips c P = 122.075 kips c P = From (1): 0.22875(122.075) 27.925 kips s P = = 27.925 1.76715 s s s P A σ = − = − 15.80 ksi s σ = −  122.075 62.233 c c c P A σ = − = − 1.962 ksi c σ = − 
  • 39. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.36 A 250-mm bar of 15 30-mm × rectangular cross section consists of two aluminum layers, 5-mm thick, brazed to a center brass layer of the same thickness. If it is subjected to centric forces of magnitude P = 30 kN, and knowing that Ea = 70 GPa and Eb = 105 GPa, determine the normal stress (a) in the aluminum layers, (b) in the brass layer. SOLUTION For each layer, 2 6 2 (30)(5) 150 mm 150 10 m A − = = = × Let load on each aluminum layer load on brass layer = = a b P P Deformation. a b a b P L P L E A E A δ = = 105 1.5 70 = = = b b a a a a E P P P P E Total force. 2 3.5 = + = a b a P P P P Solving for Pa and Pb, 2 3 7 7 a b P P P P = = (a) 3 6 6 2 2 30 10 57.1 10 Pa 7 7 150 10 a a P P A A σ − × = − = − = − = − × × 57.1 MPa a σ = −  (b) 3 6 6 3 3 30 10 85.7 10 Pa 7 7 150 10 b b P P A A σ − × = − = − = − = − × × 85.7 MPa b σ = − 
  • 40. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.37 Determine the deformation of the composite bar of Prob. 2.36 if it is subjected to centric forces of magnitude 45 kN. P = PROBLEM 2.36 A 250-mm bar of 15× 30-mm rectangular cross section consists of two aluminum layers, 5-mm thick, brazed to a center brass layer of the same thickness. If it is subjected to centric forces of magnitude 30 P = kN, and knowing that 70 a E = GPa and 105 b E = GPa, determine the normal stress (a) in the aluminum layers, (b) in the brass layer. SOLUTION For each layer, 2 6 2 (30)(5) 150 mm 150 10 m A − = = = × Let load on each aluminum layer load on brass layer = = a b P P Deformation. a b a b P L P L E A E A δ = − = − 105 1.5 70 = = = b b a a a a E P P P P E Total force. 2 3.5 Pa a b P P P = + = 2 7 a P P = 3 3 9 6 6 2 7 2 (45 10 )(250 10 ) 7 (70 10 )(150 10 ) 306 10 m a a a P L PL E A E A δ − − − = − = − × × = − × × = − × 0.306 mm δ = − 
  • 41. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.38 Compressive centric forces of 40 kips are applied at both ends of the assembly shown by means of rigid plates. Knowing that Es 6 29 10 psi = × and 6 10.1 10 psi, a E = × determine (a) the normal stresses in the steel core and the aluminum shell, (b) the deformation of the assembly. SOLUTION Let portion of axial force carried by shell portion of axial force carried by core = = a s P P a a a a a a s s s s s s P L E A P E A L P L E A P E A L δ δ δ δ = = = = Total force. ( ) a s a a s s P P P E A E A L δ = + = + a a s s P L E A E A δ ε = = + Data: 3 2 2 2 2 2 0 2 2 2 40 10 lb ( ) (2.5 1.0) 4.1233 in 4 4 (1) 0.7854 in 4 4 a i s P A d d A d π π π π = × = − = − = = = = 3 6 6 6 40 10 620.91 10 (10.1 10 )(4.1233) (29 10 )(0.7854) ε − − × = = − × × + × (a) 6 6 3 (29 10 )( 620.91 10 ) 18.01 10 psi s s E σ ε − = = × − × = − × 18.01 ksi −   6 6 3 (10.1 10 )(620.91 10 ) 6.27 10 psi a a E σ ε − = = × × = − ×  6.27 ksi −  (b) 6 3 (10)(620.91 10 ) 6.21 10 L δ ε − − = = × = − × 3 6.21 10 in. δ − = − × 
  • 42. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.39 Three wires are used to suspend the plate shown. Aluminum wires of 1 8 -in. diameter are used at A and B while a steel wire of 1 12 -in.diameter is used at C. Knowing that the allowable stress for aluminum 6 ( 10.4 10 psi) a E = × is 14 ksi and that the allowable stress for steel 6 ( 29 10 psi) s E = × is 18 ksi, determine the maximum load P that can be applied. SOLUTION By symmetry, , A B P P = and A B δ δ = Also, C A B δ δ δ δ = = = Strain in each wire: , 2 2 A B C A L L δ δ ε ε ε ε = = = = Determine allowable strain. Wires A&B: 3 3 6 4 14 10 1.3462 10 10.4 10 2 2.6924 10 A A A C A E σ ε ε ε − − × = = = × × = = × Wire C: 3 3 6 6 18 10 0.6207 10 29 10 1 0.3103 10 2 C C C A B C E σ ε ε ε ε − − × = = = × × = = = × Allowable strain for wire C governs, ∴ 3 18 10 psi C σ = × 2 6 6 2 3 1 (10.4 10 )(0.3103 10 ) 39.61 lb 4 8 39.61 lb 1 (18 10 ) 98.17 lb 4 12 σ ε ε π π σ ε σ − = =   = × × =     =   = = = × =     A A A A A A A B C C C C C C E P A E P E P A For equilibrium of the plate, 177.4 lb = + + = A B C P P P P 177.4 lb = P 
  • 43. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.40 A polystyrene rod consisting of two cylindrical portions AB and BC is restrained at both ends and supports two 6-kip loads as shown. Knowing that 6 0.45 10 psi, E = × determine (a) the reactions at A and C, (b) the normal stress in each portion of the rod. SOLUTION (a) We express that the elongation of the rod is zero: 2 2 4 4 0 BC BC AB AB AB BC P L P L d E d E π π δ = + = But AB A BC C P R P R = + = − Substituting and simplifying: 2 2 0 C BC A AB AB BC R L R L d d − = 2 2 25 2 15 1.25     = =         BC AB C A A BC AB d L R R R L d 4.2667 C A R R = (1) From the free body diagram: 12 kips A C R R + = (2) Substituting (1) into (2): 5.2667 12 A R = 2.2785 kips A R = 2.28 kips A R = ↑  From (1): 4.2667(2.2785) 9.7217 kips C R = = 9.72 kips C R = ↑  (b) 2 4 2.2785 (1.25) π σ + = = = AB A AB AB AB P R A A 1.857 ksi AB σ = +  2 4 9.7217 (2) BC C BC BC BC P R A A π σ − − = = = 3.09 ksi BC σ = − 
  • 44. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.41 Two cylindrical rods, one of steel and the other of brass, are joined at C and restrained by rigid supports at A and E. For the loading shown and knowing that 200 GPa s E = and 105 GPa, b E = determine (a) the reactions at A and E, (b) the deflection of point C. SOLUTION A to C: 9 2 3 2 3 2 6 200 10 Pa (40) 1.25664 10 mm 1.25664 10 m 4 251.327 10 N E A EA π − = × = = × = × = × C to E: 9 2 2 6 2 6 105 10 Pa (30) 706.86 mm 706.86 10 m 4 74.220 10 N E A EA π − = × = = = × = × A to B: 6 12 180 mm 0.180 m (0.180) 251.327 10 716.20 10 A A AB A P R L R PL EA R δ − = = = = = × = × B to C: 3 3 6 12 6 60 10 120 mm 0.120 m ( 60 10 )(0.120) 251.327 10 447.47 10 26.848 10 A A BC A P R L R PL EA R δ − − = − × = = − × = = × = × − ×
  • 45. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.41 (Continued) C to D: 3 3 6 9 6 60 10 100 mm 0.100 m ( 60 10 )(0.100) 74.220 10 1.34735 10 80.841 10 A A BC A P R L R PL EA R δ − − = − × = = − × = = × = × − × D to E: 3 3 6 9 6 100 10 100 mm 0.100 m ( 100 10 )(0.100) 74.220 10 1.34735 10 134.735 10 A A DE A P R L R PL EA R δ − − = − × = = − × = = × = × − × A to E: 9 6 3.85837 10 242.424 10 AE AB BC CD DE A R δ δ δ δ δ − − = + + + = × − × Since point E cannot move relative to A, 0 AE δ = (a) 9 6 3 3.85837 10 242.424 10 0 62.831 10 N A A R R − − × − × = = × 62.8 kN = ← A R  3 3 3 3 100 10 62.8 10 100 10 37.2 10 N E A R R = − × = × − × = − × 37.2 kN = ← E R  (b) 9 6 1.16367 10 26.848 10 C AB BC A R δ δ δ − − = + = × − × 9 3 6 6 (1.16369 10 )(62.831 10 ) 26.848 10 46.3 10 m − − − = × × − × = × 46.3 m C δ μ = → 
  • 46. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.42 Solve Prob. 2.41, assuming that rod AC is made of brass and rod CE is made of steel. PROBLEM 2.41 Two cylindrical rods, one of steel and the other of brass, are joined at C and restrained by rigid supports at A and E. For the loading shown and knowing that 200 s E = GPa and 105 GPa, b E = determine (a) the reactions at A and E, (b) the deflection of point C. SOLUTION A to C: 9 2 3 2 3 2 6 105 10 Pa (40) 1.25664 10 mm 1.25664 10 m 4 131.947 10 N E A EA π − = × = = × = × = × C to E: 9 2 2 6 2 6 200 10 Pa (30) 706.86 mm 706.86 10 m 4 141.372 10 N E A EA π − = × = = = × = × A to B: 6 9 180 mm 0.180 m (0.180) 131.947 10 1.36418 10 A A AB A P R L R PL EA R δ − = = = = = × = × B to C: 3 3 6 12 6 60 10 120 mm 0.120 m ( 60 10 )(0.120) 131.947 10 909.456 10 54.567 10 A A BC A P R L R PL EA R δ − − = − × = = − × = = × = × − × C to D: 3 3 6 12 6 60 10 100 mm 0.100 m ( 60 10 )(0.100) 141.372 10 707.354 10 42.441 10 A A CD A P R L R PL EA R δ − − = − × = = − × = = × = × − ×
  • 47. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.42 (Continued) D to E: 3 3 6 12 6 100 10 100 mm 0.100 m ( 100 10 )(0.100) 141.372 10 707.354 10 70.735 10 A A DE A P R L R PL EA R δ − − = − × = = − × = = × = × − × A to E: 9 6 3.68834 10 167.743 10 AE AB BC CD DE A R δ δ δ δ δ − − = + + + = × − × Since point E cannot move relative to A, 0 AE δ = (a) 9 6 3 3.68834 10 167.743 10 0 45.479 10 N A A R R − − × − × = = × 45.5 kN = ← A R  3 3 3 3 100 10 45.479 10 100 10 54.521 10 E A R R = − × = × − × = − × 54.5 kN = ← E R  (b) 9 6 2.27364 10 54.567 10 C AB BC A R δ δ δ − − = + = × − × 9 3 6 6 (2.27364 10 )(45.479 10 ) 54.567 10 48.8 10 m − − − = × × − × = × 48.8 m C δ μ = → 
  • 48. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.43 The rigid bar ABCD is suspended from four identical wires. Determine the tension in each wire caused by the load P shown. SOLUTION Deformations Let θ be the rotation of bar ABCD and , , A B C δ δ δ and D δ be the deformations of wires A, B, C, and D. From geometry, B A L δ δ θ − = B A L δ δ θ = + 2 2 C A B A L δ δ θ δ δ = + = − (1) 3 3 2 D A B A L δ δ θ δ δ = + = − (2) Since all wires are identical, the forces in the wires are proportional to the deformations. 2 C B A T T T = − (1′) 3 2 D B A T T T = − (2′)
  • 49. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.43 (Continued) Use bar ABCD as a free body. 0: 2 0 C A B D M LT LT LT Σ = − − + = (3) 0: 0 y A B C D F T T T T P Σ = + + + − = (4) Substituting (2′) into (3) and dividing by L, 4 2 0 2 A B B A T T T T − + = = (3′) Substituting (1′), (2′), and (3′) into (4), 2 3 4 0 A A A A T T T T P + + + − = 10 A T P = 1 10 A T P =  1 2 (2) 10 B A T T P   = =     1 5 B T P =  1 1 (2) 5 10 C T P P     = −         3 10 C T P =  1 1 (3) (2) 5 10 D T P P     = −         2 5 D T P = 
  • 50. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.44 The rigid bar AD is supported by two steel wires of 1 16 -in. diameter 6 ( 29 10 psi) = × E and a pin and bracket at D. Knowing that the wires were initially taut, determine (a) the additional tension in each wire when a 120-lb load P is applied at B, (b) the corresponding deflection of point B. SOLUTION Let θ be the rotation of bar ABCD. Then 24 8 A C δ θ δ θ = =  AE AE A P L AE δ = 6 2 1 4 16 3 (29 10 ) ( ) (24 ) 15 142.353 10 A AE AE EA P L π θ δ θ × = = = × CF CF C P L AE δ = ( ) 2 6 1 4 16 3 (29 10 ) (8 ) 8 88.971 10 C CF CF EA P L π θ δ θ × = = = × Using free body ABCD, 0: D M Σ = 3 3 3 24 16 8 0 24(142.353 10 ) 16(120) 8(88.971 10 ) 0 0.46510 10 rad θ θ θ − − + − = − × + − × = = × AE CF P P P 哷 (a) 3 3 (142.353 10 ) (0.46510 10 ) AE P − = × × 66.2 lb AE P =  3 3 (88.971 10 ) (0.46510 10 ) CF P − = × × 41.4 lb CF P =  (b) 3 16 16(0.46510 10 ) B δ θ − = = × 3 7.44 10 in. B δ − = × ↓ 
  • 51. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.45 The steel rods BE and CD each have a 16-mm diameter ( 200 GPa); E = the ends of the rods are single-threaded with a pitch of 2.5 mm. Knowing that after being snugly fitted, the nut at C is tightened one full turn, determine (a) the tension in rod CD, (b) the deflection of point C of the rigid member ABC. SOLUTION Let θ be the rotation of bar ABC as shown. Then 0.15 0.25 B C δ θ δ θ = = But turn CD CD C CD CD P L E A δ δ = − turn 9 2 4 3 6 ( ) (200 10 Pa) (0.016 m) (0.0025m 0.25 ) 2m 50.265 10 5.0265 10 CD CD CD C CD E A P L π δ δ θ θ = − × = − = × − × or BE BE BE BE B BE B BE BE BE P L E A P E A L δ δ = = 9 2 4 6 (200 10 Pa) (0.016 m) (0.15 ) 3 m 2.0106 10 BE P π θ θ × = = × From free body of member ABC: 0: 0.15 0.25 0 A BE CD M P P Σ = − = 6 3 6 0.15(2.0106 10 ) 0.25(50.265 10 5.0265 10 ) 0 θ θ × − × − × = 3 8.0645 10 rad θ − = × (a) 3 6 3 50.265 10 5.0265 10 (8.0645 10 ) CD P − = × − × × 3 9.7288 10 N = × 9.73 kN CD P =  (b) 3 0.25 0.25(8.0645 10 ) C δ θ − = = × 3 2.0161 10 m − = × 2.02 mm C δ = ← 
  • 52. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.46 Links BC and DE are both made of steel 6 ( 29 10 psi) E = × and are 1 2 in. wide and 1 4 in. thick. Determine (a) the force in each link when a 600-lb force P is applied to the rigid member AF shown, (b) the corresponding deflection of point A. SOLUTION Let the rigid member ACDF rotate through small angle θ clockwise about point F. Then 4 in. 2 in. δ δ θ δ δ θ = = → = − = → C BC D DE or FL EA F EA L δ δ = = For links: 2 6 6 6 6 1 1 0.125 in 2 4 4 in. 5 in. (29 10 )(0.125)(4 ) 3.625 10 4 (29 10 )(0.125)( 2 ) 1.45 10 5 δ θ θ δ θ θ    = =       = = × = = = × × − = = = − × BC DE BC BC BC DE DE DE A L L EA F L EA F L Use member ACDF as a free body. 6 6 6 3 0 : 8 4 2 0 1 1 2 4 1 1 600 (3.625 10 ) ( 1.45 10 ) 2.175 10 2 4 + 0.27586 10 rad F BC DE BC DE M P F F P F F θ θ θ θ − Σ = − + = = − = × − − × = × = × 哶 (a) 6 3 (3.625 10 )(0.27586 10 ) BC F − = × × 1000 lb BC F =  6 3 (1.45 10 )(0.27586 10 ) DE F − = − × × 400 lb = − DE F  (b) Deflection at Point A. 3 8 (8)(0.27586 10 ) A δ θ − = = × 3 2.21 10 in δ − = × → A 
  • 53. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.47 The concrete post 6 ( 3.6 10 c E = × psi and 6 5.5 10 / F) c α − = × ° is reinforced with six steel bars, each of 7 8 -in. diameter 6 ( 29 10 s E = × psi and 6 6.5 10 / F). s α − = × ° Determine the normal stresses induced in the steel and in the concrete by a temperature rise of 65°F. SOLUTION 2 2 2 7 6 6 3.6079 in 4 4 8 π π   = = =     s A d 2 2 2 10 10 3.6079 96.392 in = − = − = c s A A Let c P = tensile force developed in the concrete. For equilibrium with zero total force, the compressive force in the six steel rods equals . c P Strains: ( ) ( ) c c s s c c s s c c P P T T E A E A ε α ε α = − + Δ = + Δ Matching: c s ε ε = ( ) ( ) c c c s c c s s P P T T E A E A α α + Δ = − + Δ 6 6 6 3 1 1 ( )( ) 1 1 (1.0 10 )(65) (3.6 10 )(96.392) (29 10 )(3.6079) 5.2254 10 lb α α −   + = − Δ       + = ×   × ×   = × c s c c c s s c c P T E A E A P P 3 5.2254 10 54.210 psi 96.392 c c c P A σ × = = = 54.2 psi c σ =  3 5.2254 10 1448.32 psi 3.6079 c s s P A σ × = − = − = −  1.448 ksi s σ = − 
  • 54. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.48 The assembly shown consists of an aluminum shell 6 ( 10.6 10 psi, = × a E αa = 12.9 × 10–6 /°F) fully bonded to a steel core 6 ( 29 10 psi, = × s E αs = 6.5 × 10–6 /°F) and is unstressed. Determine (a) the largest allowable change in temperature if the stress in the aluminum shell is not to exceed 6 ksi, (b) the corresponding change in length of the assembly. SOLUTION Since , a s α α > the shell is in compression for a positive temperature rise. Let 3 6 ksi 6 10 psi a σ = − = − × ( ) 2 2 2 2 2 (1.25 0.75 ) 0.78540 in 4 4 π π = − = − = a o i A d d 2 2 2 (0.75) 0.44179 in 4 4 π π = = = s A d a a s s P A A σ σ = − = where P is the tensile force in the steel core. 3 3 (6 10 )(0.78540) 10.667 10 psi 0.44179 a a s s A A σ σ × = − = = × 3 3 6 3 6 6 ( ) ( ) ( )( ) 10.667 10 6 10 (6.4 10 )( ) 0.93385 10 29 10 10.6 10 s a s a s a s a a s s a T T E E T E E T σ σ ε α α σ σ α α − − = + Δ = + Δ − Δ = − × × × Δ = + = × × × (a) 145.91 F T Δ = ° 145.9 F Δ = ° T  (b) 3 6 3 6 10.667 10 (6.5 10 )(145.91) 1.3163 10 29 10 ε − − × = + × = × × or 3 6 3 6 6 10 (12.9 10 )(145.91) 1.3163 10 10.6 10 ε − − − × = + × = × ×  3 (8.0)(1.3163 10 ) 0.01053 in. δ ε − = = × = L  0.01053 in. δ = 
  • 55. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.49 The aluminum shell is fully bonded to the brass core and the assembly is unstressed at a temperature of 15 C. ° Considering only axial deformations, determine the stress in the aluminum when the temperature reaches 195 C. ° SOLUTION Brass core: 6 105 GPa 20.9 10 / C E α − = = × ° Aluminum shell: 6 70 GPa 23.6 10 / C E α − = = × ° Let L be the length of the assembly. Free thermal expansion: 195 15 180 C T Δ = − = ° Brass core: ( ) ( ) T b b L T δ α = Δ Aluminum shell: ( ) ( ) T a L T δ α = Δ Net expansion of shell with respect to the core: ( )( ) a b L T δ α α = − Δ Let P be the tensile force in the core and the compressive force in the shell. Brass core: 9 2 2 6 2 105 10 Pa (25) 490.87 mm 4 490.87 10 m ( ) b b P b b b E A PL E A π δ − = × = = = × =
  • 56. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.49 (Continued) Aluminum shell: 9 2 2 3 2 3 2 70 10 Pa (60 25 ) 4 2.3366 10 mm 2.3366 10 m ( ) ( ) ( )( ) a a P b P a b a b b a a E A PL PL L T KPL E A E A π δ δ δ α α − = × = − = × = × = + − Δ = + = where 9 6 9 3 9 1 1 1 1 1 (105 10 )(490.87 10 ) (70 10 )(2.3366 10 ) 25.516 10 N b b a a K E A E A − − − − = + = + × × × × = × Then 6 6 9 3 ( )( ) (23.6 10 20.9 10 )(180) 25.516 10 19.047 10 N b a T P K α α − − − − Δ = × − × = × = × Stress in aluminum: 3 6 3 19.047 10 8.15 10 Pa 2.3366 10 a a P A σ − × = − = − = − × × 8.15 MPa a σ = − 
  • 57. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.50 Solve Prob. 2.49, assuming that the core is made of steel ( 200 s E = GPa, 6 11.7 10 / C) s α − = × ° instead of brass. PROBLEM 2.49 The aluminum shell is fully bonded to the brass core and the assembly is unstressed at a temperature of 15 C. ° Considering only axial deformations, determine the stress in the aluminum when the temperature reaches 195 C. ° SOLUTION Aluminum shell: 6 70 GPa 23.6 10 / C α − = = × ° E Let L be the length of the assembly. Free thermal expansion: 195 15 180 C T Δ = − = ° Steel core: ( ) ( ) T s s L T δ α = Δ Aluminum shell: ( ) ( ) T a a L T δ α = Δ Net expansion of shell with respect to the core: ( )( ) a s L T δ α α = − Δ Let P be the tensile force in the core and the compressive force in the shell. Steel core: 9 2 2 6 2 200 10 Pa, (25) 490.87 mm 490.87 10 m 4 ( ) π δ − = × = = = × = s s P s s s E A PL E A Aluminum shell: 9 2 2 3 2 3 2 70 10 Pa ( ) (60 25) 2.3366 10 mm 2.3366 10 m 4 ( ) ( ) δ π δ δ δ − = × = = − = × = × = + a P a a a a P s P a E PL E A A ( )( ) α α − Δ = + = a s s s a a PL PL L T KPL E A E A where 9 6 9 3 9 1 1 1 1 1 (200 10 )(490.87 10 ) (70 10 )(2.3366 10 ) 16.2999 10 N − − − − = + = + × × × × = × s s a a K E A E A
  • 58. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.50 (Continued) Then 6 6 3 9 ( )( ) (23.6 10 11.7 10 )(180) 131.41 10 N 16.2999 10 α α − − − − Δ × − × = = = × × a s T P K Stress in aluminum: 3 6 3 131.19 10 56.2 10 Pa 2.3366 10 a a P A σ − × = − = − = − × × 56.2 MPa a σ = − 
  • 59. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.51 A rod consisting of two cylindrical portions AB and BC is restrained at both ends. Portion AB is made of steel ( 200 GPa, s E = 6 11.7 10 / C) s α − = × ° and portion BC is made of brass ( 105 GPa, b E = 6 20.9 10 / C). b α − = × ° Knowing that the rod is initially unstressed, determine the compressive force induced in ABC when there is a temperature rise of 50 C. ° SOLUTION 2 2 2 6 2 2 2 3 2 3 2 (30) 706.86 mm 706.86 10 m 4 4 (50) 1.9635 10 mm 1.9635 10 m 4 4 AB AB BC BC A d A d π π π π − − = = = = × = = = × = × Free thermal expansion: 6 6 6 ( ) ( ) (0.250)(11.7 10 )(50) (0.300)(20.9 10 )(50) 459.75 10 m T AB s BC b L T L T δ α α − − − = Δ + Δ = × + × = × Shortening due to induced compressive force P: 9 6 9 3 9 0.250 0.300 (200 10 )(706.86 10 ) (105 10 )(1.9635 10 ) 3.2235 10 P s AB b BC PL PL E A E A P P P δ − − − = + = + × × × × = × For zero net deflection, P T δ δ = 9 6 3 3.2235 10 459.75 10 142.62 10 N P P − − × = × = × 142.6 kN P = 
  • 60. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.52 A steel railroad track 6 s ( 200 GPa, 11.7 10 /°C) s E α − = = × was laid out at a temperature of 6°C. Determine the normal stress in the rails when the temperature reaches 48°C, assuming that the rails (a) are welded to form a continuous track, (b) are 10 m long with 3-mm gaps between them. SOLUTION (a) 6 3 ( ) (11.7 10 )(48 6)(10) 4.914 10 m T T L δ α − − = Δ = × − = × 12 9 (10) 50 10 200 10 P PL L AE E σ σ δ σ − = = = = × × 3 12 4.914 10 50 10 0 T P δ δ δ σ − − = + = × + × = 6 98.3 10 Pa σ = − × 98.3 MPa σ = − (b) 3 12 3 4.914 10 50 10 3 10 T P δ δ δ σ − − − = + = × + × = × 3 3 12 6 3 10 4.914 10 50 10 38.3 10 Pa σ − − − × − × = × = − × 38.3 MPa σ = − 
  • 61. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.53 A rod consisting of two cylindrical portions AB and BC is restrained at both ends. Portion AB is made of steel 6 ( 29 10 psi, = × s E 6 6.5 10 / F) α − = × ° s and portion BC is made of aluminum 6 ( 10.4 10 psi, = × a E 6 13.3 10 /°F). α − = × a Knowing that the rod is initially unstressed, determine (a) the normal stresses induced in portions AB and BC by a temperature rise of 70°F, (b) the corresponding deflection of point B. SOLUTION 2 2 2 2 (2.25) 3.9761 in (1.5) 1.76715 in 4 4 π π = = = = AB BC A A Free thermal expansion. 70 F T Δ = ° Total: 6 3 6 3 3 ( ) ( ) (24)(6.5 10 )(70) 10.92 10 in ( ) ( ) (32)(13.3 10 (70) 29.792 10 in. ( ) ( ) 40.712 10 in. T AB AB s T BC BC a T T AB T BC L T L T δ α δ α δ δ δ − − − − − = Δ + × = × = Δ = × = × = + = × Shortening due to induced compressive force P. 9 6 9 6 24 ( ) 208.14 10 (29 10 )(3.9761) 32 ( ) 1741.18 10 (10.4 10 )(1.76715) δ δ − − = = = × × = = = × × AB P AB s AB BC P BC a BC PL P P E A PL P P E A Total: 9 ( ) ( ) 1949.32 10 δ δ δ − = + = × P P AB P BC P For zero net deflection, P T δ δ = 9 3 1949.32 10 40.712 10 P − − × = × 3 20.885 10 lb P = × (a) 3 3 20.885 10 5.25 10 psi 3.9761 AB AB P A σ × = − = − = − × 5.25 ksi AB σ = −  3 3 20.885 10 11.82 10 psi 1.76715 BC BC P A σ × = − = − = − × 11.82 ksi BC σ = −  (b) 9 3 3 ( ) (208.14 10 )(20.885 10 ) 4.3470 10 in. P AB δ − − = × × = × 3 3 ( ) ( ) 10.92 10 4.3470 10 B T AB P AB δ δ δ − − = → + ← = × → + × ← 3 6.57 10 in. B δ − = × →  or 9 3 3 ( ) (1741.18 10 )(20.885 10 ) 36.365 10 in. P BC δ − − = × × = × 3 3 3 ( ) ( ) 29.792 10 36.365 10 6.57 10 in. B T BC P BC δ δ δ − − − = ← + → = × ← + × → = × → (checks)
  • 62. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.54 Solve Prob. 2.53, assuming that portion AB of the composite rod is made of aluminum and portion BC is made of steel. PROBLEM 2.53 A rod consisting of two cylindrical portions AB and BC is restrained at both ends. Portion AB is made of steel 6 ( 29 10 psi, = × s E 6 6.5 10 / F) α − = × ° s and portion BC is made of aluminum 6 ( 10.4 10 psi, = × a E 6 13.3 10 /°F). α − = × a Knowing that the rod is initially unstressed, determine (a) the normal stresses induced in portions AB and BC by a temperature rise of 70°F, (b) the corresponding deflection of point B. SOLUTION 2 2 (2.25) 3.9761 in 4 π = = AB A 2 2 (1.5) 1.76715 in 4 π = = BC A Free thermal expansion. 70 F T Δ = ° 6 3 6 3 ( ) ( ) (24)(13.3 10 )(70) 22.344 10 in. ( ) ( ) (32)(6.5 10 )(70) 14.56 10 in. T AB AB a T BC BC s L T L T δ α δ α − − − − = Δ = × = × = Δ = × = × Total: 3 ( ) ( ) 36.904 10 in. T T AB T BC δ δ δ − = + = × Shortening due to induced compressive force P. 9 6 9 6 24 ( ) 580.39 10 (10.4 10 )(3.9761) 32 ( ) 624.42 10 (29 10 )(1.76715) δ δ − − = = = × × = = = × × AB P AB a AB BC P BC s BC PL P P E A PL P P E A Total: 9 ( ) ( ) 1204.81 10 δ δ δ − = + = × P P AB P BC P For zero net deflection, P T δ δ = 9 3 1204.81 10 36.904 10 − − × = × P 3 30.631 10 lb P = × (a) 3 3 30.631 10 7.70 10 psi 3.9761 AB AB P A σ × = − = − = − × 7.70 ksi AB σ = −  3 3 30.631 10 17.33 10 psi 1.76715 BC BC P A σ × = − = − = − × 17.33 ksi BC σ = − 
  • 63. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.54 (Continued) (b) 9 3 3 ( ) (580.39 10 )(30.631 10 ) 17.7779 10 in. P AB δ − − = × × = × 3 3 ( ) ( ) 22.344 10 17.7779 10 B T AB P AB δ δ δ − − = → + ← = × → + × ← 3 4.57 10 in. B δ − = × →   or 9 3 3 ( ) (624.42 10 )(30.631 10 ) 19.1266 10 in. P BC δ − − = × × = × 3 3 3 ( ) ( ) 14.56 10 19.1266 10 4.57 10 in. (checks) B T BC P BC δ δ δ − − − = ← + → = × ← + × →= × →
  • 64. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.55 A brass link ( 105 GPa, b E = 6 20.9 10 / C) b α − = × ° and a steel rod (Es 200 GPa, = 6 11.7 10 / C) s α − = × ° have the dimensions shown at a temperature of 20 C. ° The steel rod is cooled until it fits freely into the link. The temperature of the whole assembly is then raised to 45 C. ° Determine (a) the final stress in the steel rod, (b) the final length of the steel rod. SOLUTION Initial dimensions at 20 C. T = ° Final dimensions at 45 C. T = ° 45 20 25 C T Δ = − = ° Free thermal expansion of each part: Brass link: 6 6 ( ) ( ) (20.9 10 )(25)(0.250) 130.625 10 m T b b T L δ α − − = Δ = × = × Steel rod: 6 6 ( ) ( ) (11.7 10 )(25)(0.250) 73.125 10 m T s s T L δ α − − = Δ = × = × At the final temperature, the difference between the free length of the steel rod and the brass link is 6 6 6 6 120 10 73.125 10 130.625 10 62.5 10 m δ − − − − = × + × − × = × Add equal but opposite forces P to elongate the brass link and contract the steel rod. Brass link: 9 105 10 Pa E = × 2 3 2 12 9 3 (2)(50)(37.5) 3750 mm 3.750 10 m (0.250) ( ) 634.92 10 (105 10 )(3.750 10 ) b P A PL P P EA δ − − − = = = × = = = × × × Steel rod: 9 200 10 Pa E = × 2 2 6 2 (30) 706.86 mm 706.86 10 m 4 s A π − = = = × 9 9 6 (0.250) ( ) 1.76838 10 (200 10 )(706.86 10 ) P s s s PL P P E A δ − − = = = × × × 9 6 3 ( ) ( ) : 2.4033 10 62.5 10 26.006 10 N δ δ δ − − + = × = × = × P b P s P P (a) Stress in steel rod: 3 6 6 (26.006 10 ) 36.8 10 Pa 706.86 10 s s P A σ − × = − = − = − × × 36.8 MPa s σ = −  (b) Final length of steel rod: 0 ( ) ( ) f T s P s L L δ δ = + − 6 6 9 3 0.250 120 10 73.125 10 (1.76838 10 )(26.003 10 ) f L − − − = + × + × − × × 0.250147 m = 250.147 mm f L = 
  • 65. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.56 Two steel bars 6 ( 200 GPa and 11.7 10 / C) s s E α − = = × ° are used to reinforce a brass bar 6 ( 105 GPa, 20.9 10 / C) b b E α − = = × ° that is subjected to a load 25 kN. P = When the steel bars were fabricated, the distance between the centers of the holes that were to fit on the pins was made 0.5 mm smaller than the 2 m needed. The steel bars were then placed in an oven to increase their length so that they would just fit on the pins. Following fabrication, the temperature in the steel bars dropped back to room temperature. Determine (a) the increase in temperature that was required to fit the steel bars on the pins, (b) the stress in the brass bar after the load is applied to it. SOLUTION (a) Required temperature change for fabrication: 3 0.5 mm 0.5 10 m T δ − = = × Temperature change required to expand steel bar by this amount: 3 6 3 6 , 0.5 10 (2.00)(11.7 10 )( ), 0.5 10 (2)(11.7 10 )( ) 21.368 C T s L T T T T T δ α − − − − = Δ × = × Δ Δ = × = × Δ Δ = ° 21.4 C °  (b) Once assembled, a tensile force P* develops in the steel, and a compressive force P* develops in the brass, in order to elongate the steel and contract the brass. Elongation of steel: 2 6 2 (2)(5)(40) 400 mm 400 10 m s A − = = = × * * 9 * 6 9 (2.00) ( ) 25 10 (400 10 )(200 10 ) P s s s F L P P A E δ − − = = = × × × Contraction of brass: 2 6 2 (40)(15) 600 mm 600 10 m b A − = = = × * * 9 * 6 9 (2.00) ( ) 31.746 10 (600 10 )(105 10 ) P b b b P L P P A E δ − − = = = × × × But ( ) ( ) P s P b δ δ + is equal to the initial amount of misfit: 3 9 * 3 * 3 ( ) ( ) 0.5 10 , 56.746 10 0.5 10 8.811 10 N P s P b P P δ δ − − − + = × × = × = × Stresses due to fabrication: Steel: * 3 * 6 6 8.811 10 22.03 10 Pa 22.03 MPa 400 10 s s P A σ − × = = = × = ×
  • 66. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.56 (Continued) Brass: * 3 * 6 6 8.811 10 14.68 10 Pa 14.68 MPa 600 10 b b P A σ − × = − = − = − × = − × To these stresses must be added the stresses due to the 25 kN load. For the added load, the additional deformation is the same for both the steel and the brass. Let δ′ be the additional displacement. Also, let Ps and Pb be the additional forces developed in the steel and brass, respectively. 6 9 6 6 9 6 (400 10 )(200 10 ) 40 10 2.00 (600 10 )(105 10 ) 31.5 10 2.00 s b s s b b s s s b b b P L P L A E A E A E P L A E P L δ δ δ δ δ δ δ − − ′ = = × × ′ ′ ′ = = = × × × ′ ′ ′ = = = × Total 3 25 10 N s b P P P = + = × 6 6 3 6 40 10 31.5 10 25 10 349.65 10 m δ δ δ − ′ ′ ′ × + × = × = × 6 6 3 6 6 3 (40 10 )(349.65 10 ) 13.986 10 N (31.5 10 )(349.65 10 ) 11.140 10 N s b P P − − = × × = × = × × = × 3 6 6 3 6 6 13.986 10 34.97 10 Pa 400 10 11.140 10 18.36 10 Pa 600 10 s s s b b b P A P A σ σ − − × = = = × × × = = = × × Add stress due to fabrication. Total stresses: 6 6 6 34.97 10 22.03 10 57.0 10 Pa s σ = × + × = × 57.0 MPa σ = s 6 6 6 18.36 10 14.68 10 3.68 10 Pa b σ = × − × = × 3.68 MPa σ = b 
  • 67. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.57 Determine the maximum load P that may be applied to the brass bar of Prob. 2.56 if the allowable stress in the steel bars is 30 MPa and the allowable stress in the brass bar is 25 MPa. PROBLEM 2.56 Two steel bars ( 200 GPa and 11.7 s s E α = = × 10–6 /°C) are used to reinforce a brass bar ( 105 GPa, 20.9 b b E α = = × 10–6 /°C) that is subjected to a load 25 kN. P = When the steel bars were fabricated, the distance between the centers of the holes that were to fit on the pins was made 0.5 mm smaller than the 2 m needed. The steel bars were then placed in an oven to increase their length so that they would just fit on the pins. Following fabrication, the temperature in the steel bars dropped back to room temperature. Determine (a) the increase in temperature that was required to fit the steel bars on the pins, (b) the stress in the brass bar after the load is applied to it. SOLUTION See solution to Problem 2.56 to obtain the fabrication stresses. * * 22.03 MPa 14.68 MPa s b σ σ = = Allowable stresses: ,all ,all 30 MPa, 25 MPa s b σ σ = = Available stress increase from load. 30 22.03 7.97 MPa 25 14.68 39.68 MPa s b σ σ = − = = + = Corresponding available strains. 6 6 9 6 6 9 7.97 10 39.85 10 200 10 39.68 10 377.9 10 105 10 s s s b b b E E σ ε σ ε − − × = = = × × × = = = × × 6 Smaller value governs 39.85 10 ε − ∴ = × Areas: 2 6 2 (2)(5)(40) 400 mm 400 10 m s A − = = = × 2 6 2 (15)(40) 600 mm 600 10 m b A − = = = × Forces 9 6 6 3 9 6 6 3 (200 10 )(400 10 )(39.85 10 ) 3.188 10 N (105 10 )(600 10 )(39.85 10 ) 2.511 10 N ε ε − − − − − = = × × × = × = = × × × = × s s s b b b P E A P E A Total allowable additional force: 3 3 3 3.188 10 2.511 10 5.70 10 N s b P P P = + = × + × = × 5.70 kN = P 
  • 68. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.58 Knowing that a 0.02-in. gap exists when the temperature is 75 F, ° determine (a) the temperature at which the normal stress in the aluminum bar will be equal to −11 ksi, (b) the corresponding exact length of the aluminum bar. SOLUTION 3 3 3 11 ksi 11 10 psi (11 10 )(2.8) 30.8 10 lb σ σ = − = − × = − = × = × a a a P A Shortening due to P: 3 3 6 6 3 (30.8 10 )(14) (30.8 10 )(18) (15 10 )(2.4) (10.6 10 )(2.8) 30.657 10 in. b a P b b a a PL PL E A E A δ − = + × × = + × × = × Available elongation for thermal expansion: 3 3 0.02 30.657 10 50.657 10 in. T δ − − = + × = × But ( ) ( ) T b b a a L T L T δ α α = Δ + Δ 6 6 6 (14)(12 10 )( ) (18)(12.9 10 )( ) 400.2 10 ) T T T − − − = × Δ + × Δ = × Δ Equating, 6 3 (400.2 10 ) 50.657 10 126.6 F T T − − × Δ = × Δ = ° (a) hot cold 75 126.6 201.6 F T T T = + Δ = + = ° hot 201.6 F = ° T  (b) ( ) a a a a a a PL L T E A δ α = Δ − 3 6 3 6 (30.8 10 )(18) (18)(12.9 10 )(26.6) 10.712 10 in. (10.6 10 )(2.8) − − × = × − = × × 3 exact 18 10.712 10 18.0107in. L − = + × = 18.0107 in. = L 
  • 69. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.59 Determine (a) the compressive force in the bars shown after a temperature rise of 180 F, ° (b) the corresponding change in length of the bronze bar. SOLUTION Thermal expansion if free of constraint: 6 6 3 ( ) ( ) (14)(12 10 )(180) (18)(12.9 10 )(180) 72.036 10 in. T b b a a L T L T δ α α − − − = Δ + Δ = × + × = × Constrained expansion: 0.02in. δ = Shortening due to induced compressive force P: 3 3 72.036 10 0.02 52.036 10 in. P δ − − = × − = × But b a b a P b b a a b b a a PL PL L L P E A E A E A E A δ   = + = +     9 6 6 14 18 995.36 10 (15 10 )(2.4) (10.6 10 )(2.8) P P −   = + = ×   × ×   Equating, 9 3 3 995.36 10 52.036 10 52.279 10 lb P P − − × = × = × (a) 52.3 kips P =  (b) ( ) b b b b b b PL L T E A δ α = Δ − 3 6 3 6 (52.279 10 )(14) (14)(12 10 )(180) 9.91 10 in. (15 10 )(2.4) − − × = × − = × × 3 9.91 10 in. δ − = × b 
  • 70. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.60 At room temperature (20 C) ° a 0.5-mm gap exists between the ends of the rods shown. At a later time when the temperature has reached 140°C, determine (a) the normal stress in the aluminum rod, (b) the change in length of the aluminum rod. SOLUTION 140 20 120 C T Δ = − = ° Free thermal expansion: 6 6 3 ( ) ( ) (0.300)(23 10 )(120) (0.250)(17.3 10 )(120) 1.347 10 m T a a s s L T L T δ α α − − − = Δ + Δ = × + × = × Shortening due to P to meet constraint: 3 3 3 1.347 10 0.5 10 0.847 10 m P δ − − − = × − × = × 9 6 9 6 9 0.300 0.250 (75 10 )(2000 10 ) (190 10 )(800 10 ) 3.6447 10 a s a s P a a s s a a s s PL PL L L P E A E A E A E A P P δ − − −   = + = +       = +   × × × ×   = × Equating, 9 3 3 3.6447 10 0.847 10 232.39 10 N P P − − × = × = × (a) 3 6 6 232.39 10 116.2 10 Pa 2000 10 a a P A σ − × = − = − = − × × 116.2 MPa σ = − a  (b) ( ) a a a a a a PL L T E A δ α = Δ − 3 6 6 9 6 (232.39 10 )(0.300) (0.300)(23 10 )(120) 363 10 m (75 10 )(2000 10 ) − − − × = × − = × × × 0.363 mm δ = a 
  • 71. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.61 A 600-lb tensile load is applied to a test coupon made from 1 16 -in. flat steel plate (E 6 29 10 psi = × and 0.30). v = Determine the resulting change (a) in the 2-in. gage length, (b) in the width of portion AB of the test coupon, (c) in the thickness of portion AB, (d) in the cross-sectional area of portion AB. SOLUTION 2 3 3 6 6 1 1 0.03125 in 2 16 600 19.2 10 psi 0.03125 19.2 10 662.07 10 29 10 σ σ ε −    = =       = = = × × = = = × × x A P A E (a) 6 0 (2.0)(662.07 10 ) x x L δ ε − = = × 3 1.324 10 in. l δ − = ×  6 6 (0.30)(662.07 10 ) 198.62 10 y z x v ε ε ε − − = = − = − × = − × (b) 6 width 0 1 ( 198.62 10 ) 2 y w δ ε −   = = − ×     6 99.3 10 in. w δ − = − ×  (c) 6 thickness 0 1 ( 198.62 10 ) 16 z t δ ε −   = = − ×     6 12.41 10 in. t δ − = − ×  (d) 0 0 (1 ) (1 ) y z A wt w t ε ε = = + + 0 0 (1 ) y z y z w t ε ε ε ε = + + + 0 0 0 6 6 6 2 ( ) 1 1 ( 198.62 10 198.62 10 negligible term) 2 16 12.41 10 in ε ε ε ε − − − Δ = − = + +    = − × − × +       = − × y z y z A A A w t 6 2 12.41 10 in − Δ = − × A 
  • 72. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.62 In a standard tensile test, a steel rod of 22-mm diameter is subjected to a tension force of 75 kN. Knowing that 0.3 v = and 200 GPa, E = determine (a) the elongation of the rod in a 200-mm gage length, (b) the change in diameter of the rod. SOLUTION 3 2 2 6 2 75 kN 75 10 N (0.022) 380.13 10 m 4 4 P A d π π − = = × = = = × 3 6 6 6 6 9 6 75 10 197.301 10 Pa 380.13 10 197.301 10 986.51 10 200 10 (200 mm)(986.51 10 ) x x x P A E L σ σ ε δ ε − − − × = = = × × × = = = × × = = × (a) 0.1973 mm δ = x   6 6 (0.3)(986.51 10 ) 295.95 10 y x v ε ε − − = − = − × = − ×   6 (22 mm)( 295.95 10 ) y y d δ ε − = = − ×   (b) 0.00651 mm δ = − y 
  • 73. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.63 A 20-mm-diameter rod made of an experimental plastic is subjected to a tensile force of magnitude P = 6 kN. Knowing that an elongation of 14 mm and a decrease in diameter of 0.85 mm are observed in a 150-mm length, determine the modulus of elasticity, the modulus of rigidity, and Poisson’s ratio for the material. SOLUTION Let the y-axis be along the length of the rod and the x-axis be transverse. 2 2 6 2 3 3 6 6 (20) 314.16 mm 314.16 10 m 6 10 N 4 6 10 19.0985 10 Pa 314.16 10 14 mm 0.093333 150 mm y y y A P P A L π σ δ ε − − = = = × = × × = = = × × = = = Modulus of elasticity: 6 6 19.0985 10 204.63 10 Pa 0.093333 y y E σ ε × = = = × 205 MPa E =  0.85 0.0425 20 x x d δ ε = = − = − Poisson’s ratio: 0.0425 0.093333 x y v ε ε − = − = − 0.455 v =  Modulus of rigidity: 6 6 204.63 10 70.31 10 Pa 2(1 ) (2)(1.455) E G v × = = = × + 70.3 MPa G = 
  • 74. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.64 The change in diameter of a large steel bolt is carefully measured as the nut is tightened. Knowing that 6 29 10 psi E = × and 0.30, v = determine the internal force in the bolt, if the diameter is observed to decrease by 3 0.5 10 in. − × SOLUTION 3 3 3 0.5 10 in. 2.5 in. 0.5 10 0.2 10 2.5 y y y d d δ ε ε − − − = − × = × = = − = − × 3 3 0.2 10 : 0.66667 10 0.3 y y x x v v ε ε ε ε − − − × = − = = = × 6 3 3 (29 10 )(0.66667 10 ) 19.3334 10 psi x x E σ ε − = = × × = × 2 2 2 (2.5) 4.9087 in 4 4 π π = = = A d 3 3 (19.3334 10 )(4.9087) 94.902 10 lb x F A σ = = × = × 94.9 kips F = 
  • 75. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.65 A 2.5-m length of a steel pipe of 300-mm outer diameter and 15-mm wall thickness is used as a column to carry a 700-kN centric axial load. Knowing that 200 GPa E = and 0.30, v = determine (a) the change in length of the pipe, (b) the change in its outer diameter, (c) the change in its wall thickness. SOLUTION ( ) 3 2 2 2 2 3 2 0.3 m 0.015 m 2.5 m 2 0.3 2(0.015) 0.27 m 700 10 N (0.3 0.27 ) 13.4303 10 m 4 4 π π − = = = = − = − = = × = − = − = × o i o o i d t L d d t P A d d (a) 3 9 3 (700 10 )(2.5) (200 10 )(13.4303 10 ) PL EA δ − × = − = − × × 6 651.51 10 m − = − × 0.652 mm δ = −  6 6 651.51 10 260.60 10 2.5 L δ ε − − − × = = = − × 6 LAT 6 (0.30)( 260.60 10 ) 78.180 10 v ε ε − − = − = − − × = × (b) 6 LAT (300 mm)(78.180 10 ) ε − Δ = = × o o d d 0.0235 mm Δ = o d  (c) 6 LAT (15 mm)(78.180 10 ) t tε − Δ = = ×  0.001173 mm t Δ = 
  • 76. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.66 An aluminum plate ( 74 E = GPa and 0.33) v = is subjected to a centric axial load that causes a normal stress σ. Knowing that, before loading, a line of slope 2:1 is scribed on the plate, determine the slope of the line when 125 σ = MPa. SOLUTION The slope after deformation is 2(1 ) tan 1 y x ε θ ε + = + 6 3 9 3 3 125 10 1.6892 10 74 10 (0.33)(1.6892 10 ) 0.5574 10 2(1 0.0005574) tan 1.99551 1 0.0016892 x x y x E v σ ε ε ε θ − − − × = = = × × = − = − × = − × − = = + tan 1.99551 θ = 
  • 77. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.67 The block shown is made of a magnesium alloy, for which 45 E = GPa and 0.35. v = Knowing that 180 x σ = − MPa, determine (a) the magnitude of y σ for which the change in the height of the block will be zero, (b) the corresponding change in the area of the face ABCD, (c) the corresponding change in the volume of the block. SOLUTION (a) 6 0 0 0 1 ( ) (0.35)( 180 10 ) y y z y x y z y x v v E v δ ε σ ε σ σ σ σ σ = = = = − − = = − × 6 63 10 Pa = − × 63 MPa y σ = −  6 3 9 6 3 9 1 (0.35)( 243 10 ) ( ) ( ) 1.89 10 45 10 1 157.95 10 ( ) 3.51 10 45 10 z z x y x y x y x x y Z v v v E E v v v E E ε σ σ σ σ σ σ σ ε σ σ σ − − − × = − − = − + = = − × × − × = − − = = − = − × × (b) 0 0 (1 ) (1 ) (1 ) ( ) ( ) x z x x z z x z x z x z x z x z x z x z x z A L L A L L L L A A A L L L L ε ε ε ε ε ε ε ε ε ε ε ε = = + + = + + + Δ = − = + + ≈ + 3 3 (100 mm)(25 mm)( 3.51 10 1.89 10 ) A − − Δ = − × − × 2 13.50 mm A Δ = −  (c) 0 0 (1 ) (1 ) (1 ) (1 ) ( small terms) ε ε ε ε ε ε ε ε ε ε ε ε ε ε ε ε ε ε = = + + + = + + + + + + + Δ = − = + + + x y z x x y y z z x y z x y z x y y z z x x y z x y z x y z V L L L V L L L L L L V V V L L L 3 3 (100)(40)(25)( 3.51 10 0 1.89 10 ) − − Δ = − × + − × V 3 540 mm Δ = − V 
  • 78. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.68 A 30-mm square was scribed on the side of a large steel pressure vessel. After pressurization, the biaxial stress condition at the square is as shown. For 200 GPa E = and 0.30, v = determine the change in length of (a) side AB, (b) side BC, (c) diagnonal AC. SOLUTION Given: 80 MPa 40 MPa x y σ σ = = Using Eq’s (2.28): 6 3 1 80 0.3(40) ( ) 340 10 200 10 x x y v E ε σ σ − − = − = = × × 6 3 1 40 0.3(80) ( ) 80 10 200 10 y y x v E ε σ σ − − = − = = × × (a) Change in length of AB. 6 3 ( ) (30 mm)(340 10 ) 10.20 10 mm AB x AB δ ε − − = = × = × 10.20 m AB δ μ =  (b) Change in length of BC. 6 3 ( ) (30 mm)(80 10 ) 2.40 10 mm BC y BC δ ε − − = = × = × 2.40 m BC δ μ =  (c) Change in length of diagonal AC. From geometry, 2 2 2 ( ) ( ) ( ) AC AB BC = + Differentiate: 2( ) ( ) 2( ) ( ) 2( ) ( ) AC AC AB AB BC BC Δ = Δ + Δ But ( ) ( ) ( ) AC AB BC AC AB BC δ δ δ Δ = Δ = Δ = Thus, 2( ) 2( ) 2( ) AC AB BC AC AB BC δ δ δ = + 1 1 (10.20 m)+ (2.40 m) 2 2 AC AB BC AB BC AC AC δ δ δ μ μ = + = 8.91 m AC δ μ = 
  • 79. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.69 The aluminum rod AD is fitted with a jacket that is used to apply a hydrostatic pressure of 6000 psi to the 12-in. portion BC of the rod. Knowing that 6 10.1 10 E = × psi and 0.36, v = determine (a) the change in the total length AD, (b) the change in diameter at the middle of the rod. SOLUTION 6 6 6 6 6000 psi 0 1 ( ) 1 [ 6000 (0.36)(0) (0.36)( 6000)] 10.1 10 380.198 10 1 ( ) 1 [ (0.36)( 6000) 0 (0.36)( 6000)] 10.1 10 427.72 10 x z y x x y z y x y z P v v E v v E σ σ σ ε σ σ σ ε σ σ σ − − = = − = − = = − − = − − − − × = − × = − + − = − − + − − × = × Length subjected to strain : 12 in. x L ε = (a) 6 (12)(427.72 10 ) y y L δ ε − = = × 3 5.13 10 in. l δ − = ×  (b) 6 (1.5)( 380.198 10 ) x x d δ ε − = = − × 3 0.570 10 in. d δ − = − × 
  • 80. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.70 For the rod of Prob. 2.69, determine the forces that should be applied to the ends A and D of the rod (a) if the axial strain in portion BC of the rod is to remain zero as the hydrostatic pressure is applied, (b) if the total length AD of the rod is to remain unchanged. PROBLEM 2.69 The aluminum rod AD is fitted with a jacket that is used to apply a hydrostatic pressure of 6000 psi to the 12-in. portion BC of the rod. Knowing that 6 10.1 10 E = × psi and 0.36, v = determine (a) the change in the total length AD, (b) the change in diameter at the middle of the rod. SOLUTION Over the pressurized portion BC, 1 ( ) ( ) 1 (2 ) x z y y y BC x y z y p v v E vp E σ σ σ σ ε σ σ σ σ = = − = = − + − = + (a) 2 2 2 ( ) 0 2 0 2 (2)(0.36)(6000) 4320 psi (1.5) 1.76715 in 4 4 (1.76715)( 4320) 7630 lb ε σ σ π π σ = + = = − = − = − = = = = = − = − y BC y y y vp vp A d F A i.e., 7630 lb compression  (b) Over unpressurized portions AB and CD, 0 x z σ σ = = ( ) ( ) y y AB y CD E σ ε ε = = For no change in length, ( ) ( ) ( ) 0 ( )( ) ( ) 0 12 (20 12) (2 ) 0 24 (24)(0.36)(6000) 2592 psi 20 20 (1.76715)( 2592) 4580 lb δ ε ε ε ε ε σ σ σ σ = + + = + + = − + + = = − = − = − = = − = − AB y AB BC y BC CD y CD AB CD y AB BC y BC y y y y L L L L L L vp E E vp P A 4580 lb compression P = 
  • 81. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.71 In many situations, physical constraints prevent strain from occurring in a given direction. For example, 0 z ε = in the case shown, where longitudinal movement of the long prism is prevented at every point. Plane sections perpendicular to the longitudinal axis remain plane and the same distance apart. Show that for this situation, which is known as plane strain, we can express , z σ , εx and y ε as follows: 2 2 ( ) 1 [(1 ) (1 ) ] 1 [(1 ) (1 ) ] z x y x x y y y x v v v v E v v v E σ σ σ ε σ σ ε σ σ = + = − − + = − − + SOLUTION 1 0 ( ) or ( ) z x y z z x y v v v E ε σ σ σ σ σ σ = = − − + = +  2 2 1 ( ) 1 [ ( )] 1 [(1 ) (1 ) ] x x y z x y x y x y v v E v v E v v v E ε σ σ σ σ σ σ σ σ σ = − − = − − + = − − +  2 2 1 ( ) 1 [ ( )] 1 [(1 ) (1 ) ] y x y z x y x y y x v v E v v E v v v E ε σ σ σ σ σ σ σ σ σ = − + − = − + − + = − − + 
  • 82. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.72 In many situations, it is known that the normal stress in a given direction is zero, for example, 0 z σ = in the case of the thin plate shown. For this case, which is known as plane stress, show that if the strains εx and εy have been determined experimentally, we can express , , σ σ x y and z ε as follows: 2 2 ( ) 1 1 1 x y y x x y z x y v v v E E v v v ε ε ε ε σ σ ε ε ε + + = = = − + − − − SOLUTION 0 1 ( ) z x x y v E σ ε σ σ = = − (1) 1 ( ) y x y v E ε σ σ = − + (2) Multiplying (2) by v and adding to (1), 2 2 1 or ( ) 1 x y x x x y v E v v E v ε ε σ σ ε ε − + = = + −  Multiplying (1) by v and adding to (2), 2 2 1 or ( ) 1 y x y y y x v E v v E v ε ε σ σ ε ε − + = = + −  1 ( ) z x y v v v E E ε σ σ = − − = − E ⋅ 2 2 ( ) 1 (1 ) ( ) ( ) 1 1 x y y x x y x y v v v v v v v v ε ε ε ε ε ε ε ε + + + − + = − + = − + − − 
  • 83. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.73 For a member under axial loading, express the normal strain ε′ in a direction forming an angle of 45° with the axis of the load in terms of the axial strain εx by (a) comparing the hypotenuses of the triangles shown in Fig. 2.49, which represent, respectively, an element before and after deformation, (b) using the values of the corresponding stresses of σ′ and σx shown in Fig. 1.38, and the generalized Hooke’s law. SOLUTION Figure 2.49 (a) 2 2 2 2 2 2 2 2 2 2 2 [ 2(1 )] (1 ) (1 ) 2(1 2 ) 1 2 1 2 4 2 2 2 x x x x x x x x x x v v v v v ε ε ε ε ε ε ε ε ε ε ε ε ε ε ε ′ + = + + − ′ ′ + + = + + + − + ′ ′ + = + − + Neglect squares as small 4 2 2 x x v ε ε ε ′ = − 1 2 x v ε ε − ′ =  (A) (B)
  • 84. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.73 (Continued) (b) 1 2 1 2 x v E E v P E A v E σ σ ε σ ′ ′ ′ = − − = ⋅ − = 1 2 x v ε − = 
  • 85. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.74 The homogeneous plate ABCD is subjected to a biaxial loading as shown. It is known that 0 z σ σ = and that the change in length of the plate in the x direction must be zero, that is, 0. x ε = Denoting by E the modulus of elasticity and by v Poisson’s ratio, determine (a) the required magnitude of , x σ (b) the ratio 0 / . z σ ε SOLUTION 0 0 , 0, 0 1 1 ( ) ( ) z y x x x y z x v v v E E σ σ σ ε ε σ σ σ σ σ = = = = − − = − (a) 0 x v σ σ =  (b) 2 2 0 0 0 1 1 1 ( ) ( 0 ) z x y z v v v v E E E ε σ σ σ σ σ σ − = − − + = − − + = 0 2 1 z E v σ ε = − 
  • 86. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.75 A vibration isolation unit consists of two blocks of hard rubber bonded to a plate AB and to rigid supports as shown. Knowing that a force of magnitude 25 kN P = causes a deflection 1.5 mm δ = of plate AB, determine the modulus of rigidity of the rubber used. SOLUTION 3 3 3 3 1 1 (25 10 N) 12.5 10 N 2 2 12.5 10 N) 833.33 10 Pa (0.15 m)(0.1m) F P F A τ = = × = × × = = = × 3 3 1.5 10 m 0.03 m 1.5 10 0.05 0.03 δ δ γ − − = × = × = = = h h 3 6 833.33 10 16.67 10 Pa 0.05 G τ γ × = = = × 16.67 MPa G = 
  • 87. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.76 A vibration isolation unit consists of two blocks of hard rubber with a modulus of rigidity 19 MPa G = bonded to a plate AB and to rigid supports as shown. Denoting by P the magnitude of the force applied to the plate and by δ the corresponding deflection, determine the effective spring constant, / , k P δ = of the system. SOLUTION Shearing strain: h δ γ = Shearing stress: G G h δ τ γ = = Force: 1 2 or 2 GA GA P A P h h δ δ τ = = = Effective spring constant: 2 P GA k h δ = = with 2 (0.15)(0.1) 0.015 m 0.03 m A h = = = 6 2 6 2(19 10 Pa)(0.015 m ) 19.00 10 N/m 0.03 m k × = = × 3 19.00 10 kN/m k = × 
  • 88. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.77 The plastic block shown is bonded to a fixed base and to a horizontal rigid plate to which a force P is applied. Knowing that for the plastic used 55 G = ksi, determine the deflection of the plate when 9 P = kips. SOLUTION Consider the plastic block. The shearing force carried is 3 9 10 lb = × P The area is 2 (3.5)(5.5) 19.25 in = = A Shearing stress: 3 9 10 467.52 psi 19.25 P A τ × = = = Shearing strain: 3 467.52 0.0085006 55 10 τ γ = = = × G But (2.2)(0.0085006) δ γ δ γ = ∴ = = h h 0.0187 in. δ = 
  • 89. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.78 A vibration isolation unit consists of two blocks of hard rubber bonded to plate AB and to rigid supports as shown. For the type and grade of rubber used all 220 τ = psi and 1800 G = psi. Knowing that a centric vertical force of magnitude 3.2 P = kips must cause a 0.1-in. vertical deflection of the plate AB, determine the smallest allowable dimensions a and b of the block. SOLUTION Consider the rubber block on the right. It carries a shearing force equal to 1 2 . P The shearing stress is 1 2 P A τ = or required area 3 2 3.2 10 7.2727 in 2 (2)(220) τ × = = = P A But (3.0) A b = Hence, 2.42 in. 3.0 = = A b min 2.42 in. = b  Use 2.42 in = b and 220 psi τ = Shearing strain. 220 0.12222 1800 G τ γ = = = But a δ γ = Hence, 0.1 0.818 in. 0.12222 δ γ = = = a min 0.818 in. = a 
  • 90. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.79 The plastic block shown is bonded to a rigid support and to a vertical plate to which a 55-kip load P is applied. Knowing that for the plastic used 150 G = ksi, determine the deflection of the plate. SOLUTION   2 3 3 3 3 3 (3.2)(4.8) 15.36 in 55 10 lb 55 10 3580.7 psi 15.36 150 10 psi 3580.7 23.871 10 150 10 2 in. τ τ γ − = = = × × = = = = × = = = × × = A P P A G G h 3 3 (2)(23.871 10 ) 47.7 10 in. h δ γ − − = = × = × 0.0477 in. δ = ↓ 
  • 91. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.80 What load P should be applied to the plate of Prob. 2.79 to produce a 1 16 -in. deflection? PROBLEM 2.79 The plastic block shown is bonded to a rigid support and to a vertical plate to which a 55-kip load P is applied. Knowing that for the plastic used 150 G = ksi, determine the deflection of the plate. SOLUTION 3 3 1 in. 0.0625 in. 16 2 in. 0.0625 0.03125 2 150 10 psi (150 10 )(0.03125) 4687.5 psi h h G G δ δ γ τ γ = = = = = = = × = = × = 2 3 (3.2)(4.8) 15.36 in (4687.5)(15.36) 72 10 lb τ = = = = = × A P A 72 kips 
  • 92. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.81 Two blocks of rubber with a modulus of rigidity 12 MPa G = are bonded to rigid supports and to a plate AB. Knowing that 100 mm c = and 45 kN, P = determine the smallest allowable dimensions a and b of the blocks if the shearing stress in the rubber is not to exceed 1.4 MPa and the deflection of the plate is to be at least 5 mm. SOLUTION Shearing strain: a G δ τ γ = = 6 6 (12 10 Pa)(0.005 m) 0.0429 m 1.4 10 Pa G a δ τ × = = = × 42.9 mm a =  Shearing stress: 1 2 2 P P A bc τ = = 3 6 45 10 N 0.1607 m 2 2(0.1 m) (1.4 10 Pa) P b cτ × = = = × 160.7 mm b = 
  • 93. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.82 Two blocks of rubber with a modulus of rigidity 10 G = MPa are bonded to rigid supports and to a plate AB. Knowing that 200 b = mm and 125 c = mm, determine the largest allowable load P and the smallest allowable thickness a of the blocks if the shearing stress in the rubber is not to exceed 1.5 MPa and the deflection of the plate is to be at least 6 mm. SOLUTION Shearing stress: 1 2 2 P P A bc τ = = 3 2 2(0.2 m)(0.125 m)(1.5 10 kPa) P bcτ = = × P 75.0 kN =  Shearing strain: a G δ τ γ = = 6 6 (10 10 Pa)(0.006 m) 0.04 m 1.5 10 Pa G a δ τ × = = = × 40.0 mm a = 
  • 94. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.83∗ Determine the dilatation e and the change in volume of the 200-mm length of the rod shown if (a) the rod is made of steel with 200 E = GPa and 0.30, v = (b) the rod is made of aluminum with 70 E = GPa and 0.35. v = SOLUTION 2 2 2 6 2 3 6 (22) 380.13 mm 380.13 10 m 4 4 46 10 N 121.01 10 Pa 0 1 ( ) (1 2 ) 1 ( ) x y z x x x y z x y z x x x y z x x x A d P P A v v E E v v E v e v v E E π π σ σ σ σ ε σ σ σ σ ε ε ε σ ε ε ε σ σ σ − = = = = × = × = = × = = = − − = = = − = − − = + + = − − = Volume: 2 3 3 (380.13 mm )(200 mm) 76.026 10 mm V AL V Ve = = = × Δ = (a) Steel: 6 6 9 (1 0.60)(121.01 10 ) 242 10 200 10 − − × = = × × e 6 242 10− = × e  3 6 3 (76.026 10 )(242 10 ) 18.40 mm − Δ = × × = V 3 18.40 mm Δ = V  (b) Aluminum: 6 6 9 (1 0.70)(121.01 10 ) 519 10 70 10 − − × = = × × e 6 519 10− = × e  3 6 3 (76.026 10 )(519 10 ) 39.4 mm − Δ = × × = V 3 39.4 mm Δ = V 
  • 95. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.84∗ Determine the change in volume of the 2-in. gage length segment AB in Prob. 2.61 (a) by computing the dilatation of the material, (b) by subtracting the original volume of portion AB from its final volume. SOLUTION From Problem 2.61, thickness = 1 16 in., E = 29 × 106 psi, v = 0.30. (a) 2 1 1 0.03125 in 2 16    = =       A 3 0 0 Volume: (0.03125)(2.00) 0.0625 in = = = V AL 3 3 6 6 6 6 6 600 19.2 10 psi 0 0.03125 1 19.2 10 ( ) 662.07 10 29 10 (0.30)(662.07 10 ) 198.62 10 264.83 10 x y z x x x y z y z x x y z P A v v E E v e σ σ σ σ ε σ σ σ ε ε ε ε ε ε − − − − = = = × = = × = − − = = = × × = = − = − × = − × = + + = × 6 6 3 0 (0.0625)(264.83 10 ) 16.55 10 in − − Δ = = × = × V V e  (b) From the solution to Problem 2.61, 3 6 6 1.324 10 in., 99.3 10 in., 12.41 10 in. δ δ δ − − − = × = − × = − × x y z The dimensions when under a 600-lb tensile load are: 3 0 6 0 6 0 3 6 3 0 Length: 2 1.324 10 2.001324 in. 1 Width: 99.3 10 0.4999007 in. 2 1 Thickness: 12.41 10 0.06248759 in. 16 Volume: 0.062516539 in 0.062516539 0.0625 16.54 10 in δ δ δ − − − − = + = + × = = + = − × = = + = − × = = = Δ = − = − = × x y z L L w w t t V Lwt V V V 
  • 96. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.85∗ A 6-in.-diameter solid steel sphere is lowered into the ocean to a point where the pressure is 7.1 ksi (about 3 miles below the surface). Knowing that 6 29 10 E = × psi and 0.30, v = determine (a) the decrease in diameter of the sphere, (b) the decrease in volume of the sphere, (c) the percent increase in the density of the sphere. SOLUTION For a solid sphere, 3 0 0 3 3 6 (6.00) 6 113.097 in. p π π σ σ σ = = = = = = − x y z V d 3 3 6 6 7.1 10 psi 1 ( ) (1 2 ) (0.4)(7.1 10 ) 29 10 97.93 10 x x y z v v E v p E ε σ σ σ − = − × = − − − × = − = − × = − × Likewise, 6 97.93 10 y z ε ε − = = − × 6 293.79 10 x y z e ε ε ε − = + + = − × (a) 6 6 0 (6.00)( 97.93 10 ) 588 10 in. ε − − −Δ = − = − − × = × x d d 6 588 10 in. − −Δ = × d  (b) 6 3 3 0 (113.097)( 293.79 10 ) 33.2 10 in − − −Δ = − = − − × = × V V e 3 3 33.2 10 in − − Δ = × V  (c) Let mass of sphere. constant. m m = = 0 0 0 (1 ) m V V V e ρ ρ ρ = = = + 0 0 0 0 0 2 3 2 3 6 6 0 0 1 1 1 1 (1 ) 1 (1 ) 1 293.79 10 100% (293.79 10 )(100%) ρ ρ ρ ρ ρ ρ ρ ρ − − − = − = × − = − + + = − + − + − = − + − + ≈ − = × − × = ×   V m V e m e e e e e e e e 0.0294% 
  • 97. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.86∗ (a) For the axial loading shown, determine the change in height and the change in volume of the brass cylinder shown. (b) Solve part a, assuming that the loading is hydrostatic with 70 x y z σ σ σ = = = − MPa. SOLUTION 0 2 2 3 2 3 2 0 0 3 3 6 3 0 0 0 135 mm 0.135 m (85) 5.6745 10 mm 5.6745 10 m 4 4 766.06 10 mm 766.06 10 m h A d V A h π π − − = = = = = × = × = = × = × (a) 6 6 6 9 0, 58 10 Pa, 0 1 58 10 ( ) 552.38 10 105 10 σ σ σ σ ε σ σ σ − = = − × = × = − + − = = − = − × × x y z y y x y z v v E E 6 0 (135 mm)( 552.38 10 ) ε − Δ = = − × y h h 0.0746 mm Δ = − h  6 6 9 (1 2 ) 1 2 (0.34)( 58 10 ) ( ) 187.81 10 105 10 σ σ σ σ − − − − × = + + = = = − × × y x y z v v e E E 3 3 6 0 (766.06 10 mm )( 187.81 10 ) − Δ = = × − × V V e 3 143.9 mm Δ = − V  (b) 6 6 6 6 9 70 10 Pa 210 10 Pa 1 1 2 (0.34)( 70 10 ) ( ) 226.67 10 105 10 σ σ σ σ σ σ ε σ σ σ σ − = = = − × + + = − × − − × = − + − = = = − × × x y z x y z y x y z y v v v E E 6 0 (135 mm)( 226.67 10 ) ε − Δ = = − × y h h 0.0306 mm Δ = − h  6 6 9 1 2 (0.34)( 210 10 ) ( ) 680 10 105 10 σ σ σ − − − × = + + = = − × × x y z v e E 3 3 6 0 (766.06 10 mm )( 680 10 ) − Δ = = × − × V V e 3 521mm Δ = − V 
  • 98. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.87∗ A vibration isolation support consists of a rod A of radius 1 10 R = mm and a tube B of inner radius 2 25 R = mm bonded to an 80-mm-long hollow rubber cylinder with a modulus of rigidity G = 12 MPa. Determine the largest allowable force P that can be applied to rod A if its deflection is not to exceed 2.50 mm. SOLUTION Let r be a radial coordinate. Over the hollow rubber cylinder, 1 2. R r R ≤ ≤ Shearing stress τ acting on a cylindrical surface of radius r is 2 P P A rh τ π = = The shearing strain is 2 P G Ghr τ γ π = = Shearing deformation over radial length dr, 2 d dr P dr d dr Gh r δ γ δ γ π = = = Total deformation. 2 2 1 1 2 1 2 1 2 1 2 1 2 ln (ln ln ) 2 2 2 ln or 2 ln( / ) R R R R R R P dr d Gh r P P r R R Gh Gh R P Gh P Gh R R R δ δ π π π π δ π = = = = − = =   1 2 Data: 10 mm 0.010 m, 25 mm 0.025 m, 80 mm 0.080 m R R h = = = = = = 6 3 6 3 3 12 10 Pa 2.50 10 m (2 )(12 10 )(0.080)(2.50 10 ) 16.46 10 N ln (0.025/0.010) G P δ π − − = × = × × × = = × 16.46 kN 
  • 99. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.88 A vibration isolation support consists of a rod A of radius R1 and a tube B of inner radius R2 bonded to a 80-mm-long hollow rubber cylinder with a modulus of rigidity G = 10.93 MPa. Determine the required value of the ratio R2/R1 if a 10-kN force P is to cause a 2-mm deflection of rod A. SOLUTION Let r be a radial coordinate. Over the hollow rubber cylinder, 1 2. R r R ≤ ≤ Shearing stress τ acting on a cylindrical surface of radius r is 2 P P A rh τ π = = The shearing strain is 2 P G Ghr τ γ π = = Shearing deformation over radial length dr, 2 δ γ δ γ δ π = = = d dr d dr P dr dr Gh r Total deformation. 2 2 1 1 2 1 2 1 2 1 2 ln (ln ln ) 2 2 ln 2 R R R R R R P dr d Gh r P P r R R Gh Gh R P Gh R δ δ π π π π = = = = − =   6 2 3 1 2 1 2 (2 )(10.93 10 )(0.080)(0.002) ln 1.0988 10.10 exp(1.0988) 3.00 R Gh R P R R π δ π × = = = = = 2 1 / 3.00 = R R 
  • 100. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.89∗ The material constants E, G, k, and v are related by Eqs. (2.33) and (2.43). Show that any one of these constants may be expressed in terms of any other two constants. For example, show that (a) k = GE/(9G − 3E) and (b) v = (3k – 2G)/(6k + 2G). SOLUTION and 3(1 2 ) 2(1 ) E E k G v v = = − + (a) 1 or 1 2 2 E E v v G G + = = − 2 2 3[2 2 4 ] 18 6 3 1 2 1 2 = = = − + −     − −         E EG EG k G E G G E E G 9 6 = − EG k G E  (b) 2(1 ) 3(1 2 ) k v G v + = − 3 6 2 2 3 2 2 6 − = + − = + k kv G Gv k G G k 3 2 6 2 − = + k G v k G 
  • 101. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.90∗ Show that for any given material, the ratio G/E of the modulus of rigidity over the modulus of elasticity is always less than 1 2 but more than 1 3 . [Hint: Refer to Eq. (2.43) and to Sec. 2.13.] SOLUTION or 2(1 ) 2(1 ) E E G v v G = = + + Assume 0 v > for almost all materials, and 1 2 < v for a positive bulk modulus. Applying the bounds, 1 2 < 2 1 3 2 E G   ≤ + =     Taking the reciprocals, 1 1 2 3 G E > > or 1 1 3 2 G E < < 
  • 102. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.91∗ A composite cube with 40-mm sides and the properties shown is made with glass polymer fibers aligned in the x direction. The cube is constrained against deformations in the y and z directions and is subjected to a tensile load of 65 kN in the x direction. Determine (a) the change in the length of the cube in the x direction, (b) the stresses , , x y σ σ and . z σ 50 GPa 0.254 15.2 GPa 0.254 15.2 GPa 0.428 x xz y xy z zy E v E v E v = = = = = = SOLUTION Stress-to-strain equations are yx y x zx z x x y z v v E E E σ σ σ ε = − − (1) xy x y zy z y x y z v v E E E σ σ σ ε = − + − (2) yz y xz x z z x y z v v E E E σ σ σ ε = − − + (3) xy yx x y v v E E = (4) yz zy y z v v E E = (5) zx xz z x v v E E = (6) The constraint conditions are 0 and 0. y z ε ε = = Using (2) and (3) with the constraint conditions gives 1 zy xy y z x y z x v v E E E σ σ σ − = (7) 1 yz xz y z x y z x v V E E E σ σ σ − + = (8) 1 0.428 0.254 or 0.428 0.077216 15.2 15.2 50 0.428 1 0.254 or 0.428 0.077216 15.2 15.2 50 y z x y z x y z x y z x σ σ σ σ σ σ σ σ σ σ σ σ − = − = − + = − + =
  • 103. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.91∗ (Continued) Solving simultaneously, 0.134993 y z x σ σ σ = = Using (4) and (5) in (1), 1 xy xz x x y z x x v v E E E ε σ σ σ = − − 2 6 2 3 6 6 3 6 9 1 [1 (0.254)(0.134993) (0.254)(0.134993)] 0.93142 (40)(40) 1600 mm 1600 10 m 65 10 40.625 10 Pa 1600 10 (0.93142)(40.625 10 ) 756.78 10 50 10 x x x x x x x E E E A P A σ σ σ ε − − − = − − = = = = × × = = = × × × = = × × (a) 6 (40 mm)(756.78 10 ) δ ε − = = × x x x L 0.0303 mm δ = x  (b) 6 40.625 10 Pa σ = × x 40.6 MPa σ = x   6 6 (0.134993)(40.625 10 ) 5.48 10 Pa σ σ = = × = × y z  5.48 MPa σ σ = = y z 
  • 104. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.92∗ The composite cube of Prob. 2.91 is constrained against deformation in the z direction and elongated in the x direction by 0.035 mm due to a tensile load in the x direction. Determine (a) the stresses , , x y σ σ and , z σ (b) the change in the dimension in the y direction. 50 GPa 0.254 15.2 GPa 0.254 15.2 GPa 0.428 x xz y xy z zy E v E v E v = = = = = = SOLUTION yx y x zx z x x y z v v E E E σ σ σ ε = − − (1) xy x y zy z y x y z v v E E E σ σ σ ε = − + − (2) yz y xz x z z x y z v v E E E σ σ σ ε = − − + (3) xy yx x y v v E E = (4) yz zy y z v v E E = (5) zx xz z x v v E E = (6) Constraint condition: 0 Load condition : 0 ε σ = = z y From Equation (3), 1 0 xz x z x z v E E σ σ = − + (0.254)(15.2) 0.077216 50 xz z z x x x v E E σ σ σ = = =
  • 105. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.92∗ (Continued) From Equation (1) with 0, y σ = 1 1 1 1 [ 0.254 ] [1 (0.254)(0.077216)] 0.98039 0.98039 zx xz x x z x z x z x x x z x x x x x x x x v v E E E E E E E E ε σ σ σ σ σ σ σ σ ε σ = − = − = − = − = = But, 6 0.035 mm 875 10 40 mm x x x L δ ε − = = = × (a) 9 6 3 (50 10 )(875 10 ) 44.625 10 Pa 0.98039 σ − × × = = × x 44.6 MPa σ = x  0 y σ =  6 6 (0.077216)(44.625 10 ) 3.446 10 Pa σ = × = × z 3.45 MPa σ = z  From (2), 6 6 9 9 6 1 (0.254)(44.625 10 ) (0.428)(3.446 10 ) 0 50 10 15.2 10 323.73 10 xy zy y x y z x y z v v E E E ε σ σ σ − = + − × × = − + − × × = − × (b) 6 (40 mm)( 323.73 10 ) δ ε − = = − × y y y L 0.0129 mm δ = − y 
  • 106. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.93 Two holes have been drilled through a long steel bar that is subjected to a centric axial load as shown. For 6.5 P = kips, determine the maximum value of the stress (a) at A, (b) at B. SOLUTION (a) At hole A: 1 1 1 in. 2 2 4 r = ⋅ = 1 3 2.50 in. 2 = − = d 2 net 1 (2.50) 1.25 in 2   = = =     A dt non net 6.5 5.2 ksi 1.25 P A σ = = = ( ) 1 4 2 2 0.1667 3 r D = = From Fig. 2.60a, 2.56 K = max non (2.56)(5.2) σ σ = = K max 13.31ksi σ =  (b) At hole B: 1 (1.5) 0.75, 3 1.5 1.5 in. 2 r d = = = − = 2 net non net 1 6.5 (1.5) 0.75 in , 8.667 ksi 2 0.75 σ   = = = = = =     P A dt A 2 2(0.75) 0.5 3 r D = = From Fig. 2.60a, 2.16 K = max non (2.16)(8.667) σ σ = = K max 18.72 ksi σ = 
  • 107. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.94 Knowing that all 16 ksi, σ = determine the maximum allowable value of the centric axial load P. SOLUTION At hole A: 1 1 1 in. 2 2 4 = ⋅ = r 1 3 2.50 in. 2 = − = d 2 net 1 (2.50) 1.25 in 2   = = =     A dt ( ) 1 4 2 2 0.1667 3 r D = = From Fig. 2.60a, 2.56 K = net max max net (1.25)(16) 7.81 kips 2.56 KP A P A K σ σ = ∴ = = = At hole B: 1 (1.5) 0.75 in, 3 1.5 1.5 in. 2 = = = − = r d 2 net 1 (1.5) 0.75 in , 2   = = =     A dt 2 2(0.75) 0.5 3 r D = = From Fig. 2.60a, 2.16 K = net max (0.75)(16) 5.56 kips 2.16 A P K σ = = = Smaller value for P controls. 5.56 kips P = 
  • 108. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.95 Knowing that the hole has a diameter of 9 mm, determine (a) the radius rf of the fillets for which the same maximum stress occurs at the hole A and at the fillets, (b) the corresponding maximum allowable load P if the allowable stress is 100 MPa. SOLUTION For the circular hole, 1 (9) 4.5 mm 2 r   = =     2 2(4.5) 96 9 87 mm 0.09375 96 r d D = − = = = 6 2 net (0.087 m)(0.009 m) 783 10 m A dt − = = = × From Fig. 2.60a, hole 2.72 K = hole max net K P A σ = 6 6 3 net max hole (783 10 )(100 10 ) 28.787 10 N 2.72 A P K σ − × × = = = × (a) For fillet, 96 mm, 60 mm D d = = 96 1.60 60 D d = = 6 2 min (0.060 m)(0.009 m) 540 10 m A dt − = = = × 6 6 fillet min max max fillet 3 min (5.40 10 )(100 10 ) 28.787 10 1.876 K P A A P K σ σ − × × = = = × = ∴ From Fig. 2.60b, 0.19 0.19 0.19(60) f f r r d d ≈ ∴ ≈ = 11.4 mm f r =  (b) 28.8 kN P = 
  • 109. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.96 For 100 kN, P = determine the minimum plate thickness t required if the allowable stress is 125 MPa. SOLUTION At the hole: 20 mm 88 40 48 mm A A r d = = − = 2 2(20) 0.455 88 A A r D = = From Fig. 2.60a, 2.20 K = max net max 3 3 6 (2.20)(100 10 N) 36.7 10 m 36.7 mm (0.048 m)(125 10 Pa) A A KP KP KP t A d t d t σ σ − = = ∴ = × = = × = × At the fillet: 88 88 mm, 64 mm 1.375 64 B B D D d d = = = = 15 15 mm 0.2344 64 B B B r r d = = = From Fig. 2.60b, 1.70 K = max min B KP KP A d t σ = = 3 3 6 max (1.70)(100 10 N) 21.25 10 m 21.25 mm (0.064 m)(125 10 Pa) B KP t d σ − × = = = × = × The larger value is the required minimum plate thickness.  36.7 mm t = 
  • 110. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.97 The aluminum test specimen shown is subjected to two equal and opposite centric axial forces of magnitude P. (a) Knowing that E = 70 GPa and all σ = 200 MPa, determine the maximum allowable value of P and the corresponding total elongation of the specimen. (b) Solve part a, assuming that the specimen has been replaced by an aluminum bar of the same length and a uniform 60 × 15-mm rectangular cross section. SOLUTION 6 9 all 2 6 2 min 200 10 Pa 70 10 Pa (60 mm)(15 mm) 900 mm 900 10 m E A σ − = × = × = = = × (a) Test specimen. 75 mm, 60 mm, 6 mm D d r = = = 75 6 1.25 0.10 60 60 D r d d = = = = From Fig. 2.60b max 1.95 P K K A σ = = 6 6 3 max (900 10 )(200 10 ) 92.308 10 N 1.95 A P K σ − × × = = = × 92.3 kN P =  Wide area * 2 3 2 (75 mm)(15 mm) 1125 mm 1.125 10 m A − = = = × 3 9 3 6 3 6 92.308 10 0.150 0.300 0.150 70 10 1.125 10 900 10 1.125 10 7.91 10 m i i i i i i PL L P A E E A δ − − − − ×   = Σ = Σ = + +   × × × ×   = × 0.791 mm δ =  (b) Uniform bar. 6 6 3 all (900 10 )(200 10 ) 180 10 N P Aσ − = = × × = × 180.0 kN P =   3 3 6 9 (180 10 )(0.600) 1.714 10 m (900 10 )(70 10 ) PL AE δ − − × = = = × × ×  1.714 mm δ = 
  • 111. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.98 For the test specimen of Prob. 2.97, determine the maximum value of the normal stress corresponding to a total elongation of 0.75 mm. PROBLEM 2.97 The aluminum test specimen shown is subjected to two equal and opposite centric axial forces of magnitude P. (a) Knowing that E = 70 GPa and all 200 σ = MPa, determine the maximum allowable value of P and the corresponding total elongation of the specimen. (b) Solve part a, assuming that the specimen has been replaced by an aluminum bar of the same length and a uniform 60 15-mm × rectangular cross section. SOLUTION 3 1 3 2 2 3 2 1 3 2 6 2 2 0.75 10 m 150 mm 0.150 m, 300 mm 0.300 m (75 mm)(15 mm) 1125 mm 1.125 10 m (60 mm)(15 mm) 900 mm 900 10 m i i i i i i PL L P E A E A L L L A A A δ δ − − − = Σ = Σ = × = = = = = = = = = × = = = × 1 3 6 3 9 3 3 0.150 0.300 0.150 600 m 1.125 10 900 10 1.125 10 (70 10 )(0.75 10 ) 87.5 10 N 600 δ − − − − − Σ = + + = × × × × × = = = × Σ i i i i L A E P L A Stress concentration. 75 mm, 60 mm, 6 mm D d r = = = 75 6 1.25 0.10 60 60 D r d d = = = = From Fig. 2.60b 1.95 K = 3 6 max 6 min (1.95)(87.5 10 ) 189.6 10 Pa 900 10 P K A σ − × = = = × × max 189.6 MPa σ =  Note that max all. σ σ < 
  • 112. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.99 A hole is to be drilled in the plate at A. The diameters of the bits available to drill the hole range from 1 2 to 11 /2 in. in 1 4 -in. increments. If the allowable stress in the plate is 21 ksi, determine (a) the diameter d of the largest bit that can be used if the allowable load P at the hole is to exceed that at the fillets, (b) the corresponding allowable load P. SOLUTION At the fillets: 4.6875 0.375 1.5 0.12 3.125 3.125 D r d d = = = = From Fig. 2.60b, 2.10 K = 2 min all max all min min all all (3.125)(0.5) 1.5625 in (1.5625)(21) 15.625 kips 2.10 σ σ σ = = = = = = = A P K A A P K At the hole: net ( 2 ) , from Fig. 2.60 = − A D r t K a net all max all all net σ σ σ = = ∴ = P A K P A K with all 4.6875 in. 0.5 in. 21 ksi D t σ = = = Hole diam. r 2 d D r = − 2 / r D K net A all P 0.5 in. 0.25 in. 4.1875 in. 0.107 2.68 2.0938 in2 16.41 kips 0.75 in. 0.375 in. 3.9375 in. 0.16 2.58 1.96875 in2 16.02 kips 1 in. 0.5 in. 3.6875 in. 0.213 2.49 1.84375 in2 15.55 kips 1.25 in. 0.625 in. 3.4375 in. 0.267 2.41 1.71875 in2 14.98 kips 1.5 in. 0.75 in. 3.1875 in. 0.32 2.34 1.59375 in2 14.30 kips (a) Largest hole with all 15.625 kips P > is the 3 4 -in. diameter hole.  (b) Allowable load all 15.63 kips P = 
  • 113. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.100 (a) For 13 kips P = and 1 2 in., d = determine the maximum stress in the plate shown. (b) Solve part a, assuming that the hole at A is not drilled. SOLUTION Maximum stress at hole: Use Fig. 2.60a for values of K. 2 net max net 2 0.5 0.017, 2.68 4.6875 (0.5)(4.6875 0.5) 2.0938 in (2.68)(13) 16.64 ksi, 2.0938 σ = = = = − = = = = r K D A P K A Maximum stress at fillets: Use Fig. 2.60b for values of K. 0.375 4.6875 0.12 1.5 3.125 3.125 r D d d = = = = 2.10 K = 2 min max min (0.5)(3.125) 1.5625 in (2.10)(13) 17.47 ksi 1.5625 σ = = = = = A P K A (a) With hole and fillets: 17.47 ksi  (b) Without hole: 17.47 ksi 
  • 114. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.101 Rod ABC consists of two cylindrical portions AB and BC; it is made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = A force P is applied to the rod and then removed to give it a permanent set 2 p δ = mm. Determine the maximum value of the force P and the maximum amount m δ by which the rod should be stretched to give it the desired permanent set. SOLUTION 2 2 6 2 2 3 2 3 2 6 6 3 max min (30) 706.86 mm 706.86 10 m 4 (40) 1.25664 10 mm 1.25664 10 m 4 (706.86 10 )(250 10 ) 176.715 10 N AB BC Y A A P A π π σ − − − = = = × = = × = × = = × × = × max 176.7 kN P =  3 3 9 6 9 3 3 (176.715 10 )(0.8) (176.715 10 )(1.2) (200 10 )(706.86 10 ) (200 10 )(1.25664 10 ) 1.84375 10 m 1.84375 mm BC AB AB BC P L P L EA EA δ − − − ′ ′ × × ′ = + = + × × × × = × = or 2 1.84375 p m m p δ δ δ δ δ δ ′ ′ = − = + = + 3.84 mm m δ = 
  • 115. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.102 Rod ABC consists of two cylindrical portions AB and BC; it is made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = A force P is applied to the rod until its end A has moved down by an amount 5 mm. m δ = Determine the maximum value of the force P and the permanent set of the rod after the force has been removed. SOLUTION 2 2 6 2 2 3 2 3 2 6 6 3 max min (30) 706.86 mm 706.86 10 m 4 (40) 1.25664 10 mm 1.25644 10 m 4 (706.86 10 )(250 10 ) 176.715 10 N AB BC Y A A P A π π σ − − − = = = × = = × = × = = × × = × max 176.7 kN P =  3 3 9 6 9 3 3 (176.715 10 )(0.8) (176.715 10 )(1.2) (200 10 )(706.68 10 ) (200 10 )(1.25664 10 ) 1.84375 10 m 1.84375 mm BC AB AB BC P L P L EA EA δ − − − ′ ′ × × ′ = + = + × × × × = × = 5 1.84375 3.16 mm p m δ δ δ′ = − = − = 3.16 mm p δ = 
  • 116. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.103 The 30-mm square bar AB has a length 2.2 m; L = it is made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 345 MPa. Y σ = A force P is applied to the bar until end A has moved down by an amount . m δ Determine the maximum value of the force P and the permanent set of the bar after the force has been removed, knowing that (a) 4.5 mm, m δ = (b) 8 mm. m δ = SOLUTION 2 6 2 6 3 9 (30)(30) 900 mm 900 10 m (2.2)(345 10 ) 3.795 10 3.795 mm 200 10 Y Y Y A L L E σ δ ε − − = = = × × = = = = × = × If 6 6 3 , (900 10 )(345 10 ) 310.5 10 N δ δ σ − ≥ = = × × = × m Y m Y P A Unloading: 3.795 mm m Y Y P L L AE E σ δ δ ′ = = = = P m δ δ δ′ = − (a) 3 4.5 mm 310.5 10 N δ δ = > = × m Y m P 310.5 kN δ = m  perm 4.5 mm 3.795 mm δ = − perm 0.705 mm δ =  (b) 3 8 mm 310.5 10 N δ δ = > = × m Y m P 310.5 kN δ = m   perm 8.0 mm 3.795 mm δ = − perm 4.205 mm δ = 
  • 117. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.104 The 30-mm square bar AB has a length 2.5m; L = it is made of mild steel that is assumed to be elastoplastic with 200 GPa E = and 345 MPa. Y σ = A force P is applied to the bar and then removed to give it a permanent set . p δ Determine the maximum value of the force P and the maximum amount m δ by which the bar should be stretched if the desired value of p δ is (a) 3.5 mm, (b) 6.5 mm. SOLUTION 2 6 2 6 3 9 (30)(30) 900 mm 900 10 m (2.5)(345 10 ) 4.3125 10 m 4.3125 mm 200 10 Y Y Y A L L E σ δ ε − = = = × × = = = = × = × When m δ exceeds , Y δ thus producing a permanent stretch of , p δ the maximum force is 6 6 3 (900 10 )(345 10 ) 310.5 10 N σ − = = × × = × m Y P A 310.5 kN =  δ δ δ δ δ δ δ δ ′ = − = − ∴ = + p m m Y m p Y (a) 3.5 mm 3.5 mm 4.3125 mm δ δ = = + p m 7.81 mm =  (b) 6.5 mm 6.5 mm 4.3125 mm δ δ = = + p m 10.81 mm = 
  • 118. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.105 Rod AB is made of a mild steel that is assumed to be elastoplastic with 6 29 10 psi E = × and 36 ksi. Y σ = After the rod has been attached to the rigid lever CD, it is found that end C is 3 8 in. too high. A vertical force Q is then applied at C until this point has moved to position . C′ Determine the required magnitude of Q and the deflection 1 δ if the lever is to snap back to a horizontal position after Q is removed. SOLUTION Since the rod AB is to be stretched permanently, the peak force in the rod is , Y P P = where 2 3 (36) 3.976 kips 4 8 Y Y P A π σ   = = =     Referring to the free body diagram of lever CD, 0: 33 22 0 22 (22)(3.976) 2.65 kips 33 33 Σ = − = = = = D M Q P Q P 2.65 kips = Q  During unloading, the spring back at B is 3 6 (60)(36 10 ) 0.0745 in. 29 10 AB Y B AB Y L L E σ δ ε × = = = = × From the deformation diagram, Slope: 33 0.1117 in. 22 33 22 C B C B δ δ θ δ δ = = ∴ = = − 0.1117 in. δ = C 
  • 119. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.106 Solve Prob. 2.105, assuming that the yield point of the mild steel is 50 ksi. PROBLEM 2.105 Rod AB is made of a mild steel that is assumed to be elastoplastic with 6 29 10 psi E = × and 36 ksi. Y σ = After the rod has been attached to the rigid lever CD, it is found that end C is 3 8 in. too high. A vertical force Q is then applied at C until this point has moved to position C′. Determine the required magnitude of Q and the deflection 1 δ if the lever is to snap back to a horizontal position after Q is removed. SOLUTION Since the rod AB is to be stretched permanently, the peak force in the rod is , Y P P = where 2 3 (50) 5.522 kips 4 8 Y Y P A π σ   = = =     Referring to the free body diagram of lever CD, 0: 33 22 0 D M Q P Σ = − = 22 (22)(5.522) 3.68 kips 33 33 = = = Q P 3.68 kips = Q  During unloading, the spring back at B is 3 6 (60)(50 10 ) 0.1034 in. 29 10 σ δ ε × = = = = × AB Y B AB Y L L E From the deformation diagram, Slope: 33 22 33 22 C B C B δ δ θ δ δ = = ∴ = 0.1552 in. δ = C 
  • 120. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.107 Each cable has a cross-sectional area of 100 mm2 and is made of an elastoplastic material for which 345 MPa Y σ = and 200 GPa. E = A force Q is applied at C to the rigid bar ABC and is gradually increased from 0 to 50 kN and then reduced to zero. Knowing that the cables were initially taut, determine (a) the maximum stress that occurs in cable BD, (b) the maximum deflection of point C, (c) the final displacement of point C. (Hint: In Part c, cable CE is not taut.) SOLUTION Elongation constraints for taut cables. Let rotation angle of rigid bar . θ = ABC CE BD AB AC L L δ δ θ = = 1 2 δ δ δ = = AB BD CE CE AC L L (1) Equilibrium of bar ABC. 0 : 0 A AB BD AC CE AC M L F L F L Q = + − = 1 2 AB CE BD CE BD AC L Q F F F F L = + = + (2) Assume cable CE is yielded. 6 6 3 (100 10 )(345 10 ) 34.5 10 N CE Y F Aσ − = = × × = × From (2), 3 3 3 2( ) (2)(50 10 34.5 10 ) 31.0 10 N BD CE F Q F = − = × − × = × Since 3 < 34.5 10 N, BD Y F Aσ = × cable BD is elastic when 50 kN. Q =
  • 121. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.107 (Continued) (a) Maximum stresses. 345 MPa CE Y σ σ = = 3 6 6 31.0 10 310 10 Pa 100 10 BD BD F A σ − × = = = × × 310 MPa BD σ =  (b) Maximum of deflection of point C. 3 3 9 6 (31.0 10 )(2) 3.1 10 m (200 10 )(100 10 ) BD BD BD F L EA δ − − × = = = × × × From (1), 3 2 6.2 10 m C CE BD δ δ δ − = = = × 6.20 mm ↓  Permanent elongation of cable CE: ( ) ( ) σ δ δ = − Y CE CE p CE L E max max 6 3 3 9 ( ) ( ) ( ) (345 10 )(2) 6.20 10 2.75 10 m 200 10 CE CE Y CE CE P CE CE F L L EA E σ δ δ δ − − = − = − × = × − = × × (c) Unloading. Cable CE is slack ( 0) CE F = at 0. Q = From (2), 2( ) 2(0 0) 0 BD CE F Q F = − = − = Since cable BD remained elastic, 0. BD BD BD F L EA δ = = 
  • 122. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.108 Solve Prob. 2.107, assuming that the cables are replaced by rods of the same cross-sectional area and material. Further assume that the rods are braced so that they can carry compressive forces. PROBLEM 2.107 Each cable has a cross-sectional area of 100 mm2 and is made of an elastoplastic material for which 345 MPa Y σ = and 200 GPa. E = A force Q is applied at C to the rigid bar ABC and is gradually increased from 0 to 50 kN and then reduced to zero. Knowing that the cables were initially taut, determine (a) the maximum stress that occurs in cable BD, (b) the maximum deflection of point C, (c) the final displacement of point C. (Hint: In Part c, cable CE is not taut.) SOLUTION Elongation constraints. Let rotation angle of rigid bar . ABC θ = δ δ θ = = BC CE AB AC L L 1 2 δ δ δ = = AB BD CE CE AC L L (1) Equilibrium of bar ABC. 0: 0 = + − = A AB BD AC CE AC M L F L F L Q 1 2 AB CE BD CE BD AC L Q F F F F L = + = + (2) Assume cable CE is yielded. 6 6 3 (100 10 )(345 10 ) 34.5 10 N CE Y F Aσ − = = × × = × From (2), 3 3 3 2( ) (2)(50 10 34.5 10 ) 31.0 10 N BD CE F Q F = − = × − × = × Since 3 34.5 10 N, BD Y F Aσ < = × cable BD is elastic when 50 kN. Q =
  • 123. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.108 (Continued) (a) Maximum stresses. 345 MPa CE Y σ σ = = 3 6 6 31.0 10 310 10 Pa 100 10 BD BD F A σ − × = = = × × 310 MPa BD σ =  (b) Maximum of deflection of point C. 3 3 9 6 (31.0 10 )(2) 3.1 10 m (200 10 )(100 10 ) BD BD BD F L EA δ − − × = = = × × × From (1), 3 2 6.2 10 m C CE BD δ δ δ − = = = × 6.20 mm ↓  Unloading. 3 50 10 N, CE C Q δ δ ′ ′ ′ = × = From (1), 1 2 BD C δ δ ′ ′ = Elastic 9 6 1 6 2 (200 10 )(100 10 )( ) 5 10 2 C BD BD C BD EA F L δ δ δ − ′ × × ′ ′′ ′ = = = × 9 6 6 (200 10 )(100 10 )( ) 10 10 2 CE C CE C CE EA F L δ δ δ − ′ ′ × × ′ ′ = = = × From (2), 6 1 2 12.5 10 CE BD C Q F F δ ′ ′ ′ ′ = + = × Equating expressions for , ′ Q 6 3 12.5 10 50 10 C δ ′ × = × 3 4 10 m C δ − ′ = × (c) Final displacement. 3 3 3 ( ) 6.2 10 4 10 2.2 10 m C C m C δ δ δ − − − ′ = − = × − × = × 2.20 mm ↓ 
  • 124. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.109 Rod AB consists of two cylindrical portions AC and BC, each with a cross-sectional area of 1750 mm2 . Portion AC is made of a mild steel with 200 GPa E = and 250 MPa, Y σ = and portion CB is made of a high-strength steel with 200 GPa E = and 345 MPa. Y σ = A load P is applied at C as shown. Assuming both steels to be elastoplastic, determine (a) the maximum deflection of C if P is gradually increased from zero to 975 kN and then reduced back to zero, (b) the maximum stress in each portion of the rod, (c) the permanent deflection of C. SOLUTION Displacement at C to cause yielding of AC. 6 , 3 , , 9 (0.190)(250 10 ) 0.2375 10 m 200 10 σ δ ε − × = = = = × × AC Y AC C Y AC Y AC L L E Corresponding force. 6 6 3 , (1750 10 )(250 10 ) 437.5 10 N σ − = = × × = × AC Y AC F A 9 6 3 3 (200 10 )(1750 10 )(0.2375 10 ) 437.5 10 N 0.190 C CB CB EA F L δ − − × × × = − = − = − × For equilibrium of element at C, 3 ( ) 0 875 10 N AC CB Y Y AC CB F F P P F F − + = = − = × Since applied load 3 3 975 10 N 875 10 N, P = × > × portion AC yields. 3 3 3 437.5 10 975 10 N 537.5 10 N CB AC F F P = − = × − × = − × (a) 3 3 9 6 (537.5 10 )(0.190) 0.29179 10 m (200 10 )(1750 10 ) CB CD C F L EA δ − − × = − = = × × × 0.292 mm  (b) Maximum stresses: , 250 MPa σ σ = = AC Y AC 250 MPa  3 6 6 537.5 10 307.14 10 Pa 307 MPa 1750 10 σ − × = = − = − × = − × BC BC F A 307 MPa −  (c) Deflection and forces for unloading.  3 3 3 3 9 6 975 10 2 487.5 10 N (487.5 10 )(0.190) 0.26464 10 m (200 10 )(1750 10 ) AC AC CB CB AC CB AC AC AB AC CB AC AC P L P L L P P P EA EA L P P P P P δ δ − − ′ ′ ′ ′ ′ ′ = = − ∴ = − = − ′ ′ ′ ′ ′ = × = − = = × × ′ = = × × × 3 3 3 0.29179 10 0.26464 10 0.02715 10 m δ δ δ − − − ′ = − = × − × = × p m 0.0272 mm 
  • 125. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.110 For the composite rod of Prob. 2.109, if P is gradually increased from zero until the deflection of point C reaches a maximum value of 0.3 mm m δ = and then decreased back to zero, determine (a) the maximum value of P, (b) the maximum stress in each portion of the rod, (c) the permanent deflection of C after the load is removed. PROBLEM 2.109 Rod AB consists of two cylindrical portions AC and BC, each with a cross-sectional area of 1750 mm2 . Portion AC is made of a mild steel with 200 E = GPa and 250 MPa, Y σ = and portion CB is made of a high-strength steel with 200 = E GPa and 345 MPa. Y σ = A load P is applied at C as shown. Assuming both steels to be elastoplastic, determine (a) the maximum deflection of C if P is gradually increased from zero to 975 kN and then reduced back to zero, (b) the maximum stress in each portion of the rod, (c) the permanent deflection of C. SOLUTION Displacement at C is 0.30 mm. m δ = The corresponding strains are 3 3 0.30 mm 1.5789 10 190 mm 0.30 mm 1.5789 10 190 mm m AC AC m CB CB L L δ ε δ ε − − = = = × = − = − = − × Strains at initial yielding: 6 , 3 , 9 6 , 3 , 9 250 10 1.25 10 (yielding) 200 10 345 10 1.725 10 (elastic) 200 10 σ ε σ ε − − × = = = × × × = = − = − × × Y AC Y AC Y BC Y CB E E (a) Forces: 6 6 3 (1750 10 )(250 10 ) 437.5 10 N AC Y F Aσ − − = = × × = × 9 6 3 3 (200 10 )(1750 10 )( 1.5789 10 ) 552.6 10 N CB CB F EAε − − − = = × × − × = − × For equilibrium of element at C, 0 AC CB F F P − − = 3 3 3 437.5 10 552.6 10 990.1 10 N = − = × + × = × AC CD P F F 990 kN =  (b) Stresses: , : σ σ = AC Y AC AC 250 MPa =  3 6 6 552.6 10 : 316 10 Pa 1750 10 σ − × = = − = − × × CB CB F CB A 316 MPa − 
  • 126. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.110 (Continued) (c) Deflection and forces for unloading. 3 3 3 3 9 6 2 990.1 10 N 495.05 10 N (495.05 10 )(0.190) 0.26874 10 m 0.26874 mm (200 10 )(1750 10 ) AC AC CB CB AC CB AC AC AB AC CB AC AC P L P L L P P P EA EA L P P P P P δ δ − − ′ ′ ′ ′ ′ = = − ∴ = − = − ′ ′ ′ ′ ′ = − = = × ∴ = × × ′ = = × = × × 0.30 mm 0.26874 mm δ δ δ ′ = − = − p m 0.031mm 
  • 127. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.111 Two tempered-steel bars, each 3 16 -in. thick, are bonded to a 1 2 -in. mild-steel bar. This composite bar is subjected as shown to a centric axial load of magnitude P. Both steels are elastoplastic with 6 29 10 E = × and with yield strengths equal to 100 ksi and 50 ksi, respectively, for the tempered and mild steel. The load P is gradually increased from zero until the deformation of the bar reaches a maximum value 0.04 in. m δ = and then decreased back to zero. Determine (a) the maximum value of P, (b) the maximum stress in the tempered-steel bars, (c) the permanent set after the load is removed. SOLUTION For the mild steel, 2 1 1 (2) 1.00 in 2   = =     A 3 1 1 6 (14)(50 10 ) 0.024138 in. 29 10 σ δ × = = = × Y Y L E For the tempered steel, 2 2 3 2 (2) 0.75 in 16   = =     A 3 2 2 3 (14)(100 10 ) 0.048276 in. 29 10 σ δ × = = = × Y Y L E Total area: 2 1 2 1.75 in = + = A A A 1 2. Y m Y δ δ δ < < The mild steel yields. Tempered steel is elastic. (a) Forces: 3 3 1 1 1 (1.00)(50 10 ) 50 10 lb σ = = × = × Y P A 3 3 2 2 (29 10 )(0.75)(0.04) 62.14 10 lb 14 δ × = = = × m EA P L 3 1 2 112.14 10 lb 112.1kips = + = × = P P P 112.1 kips = P  (b) Stresses: 3 1 1 1 1 50 10 psi 50 ksi Y P A σ σ = = = × = 3 3 2 2 2 62.14 10 82.86 10 psi 82.86 ksi 0.75 σ × = = = × = P A 82.86 ksi  Unloading: 3 6 (112.14 10 )(14) 0.03094 in. (29 10 )(1.75) δ × ′ = = = × PL EA (c) Permanent set: 0.04 0.03094 0.00906 in. p m δ δ δ ′ = − = − = 0.00906in. 
  • 128. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.112 For the composite bar of Prob. 2.111, if P is gradually increased from zero to 98 kips and then decreased back to zero, determine (a) the maximum deformation of the bar, (b) the maximum stress in the tempered-steel bars, (c) the permanent set after the load is removed. PROBLEM 2.111 Two tempered-steel bars, each 3 16 -in. thick, are bonded to a 1 2 -in. mild-steel bar. This composite bar is subjected as shown to a centric axial load of magnitude P. Both steels are elastoplastic with 6 29 10 E = × psi and with yield strengths equal to 100 ksi and 50 ksi, respectively, for the tempered and mild steel. SOLUTION Areas: Mild steel: 2 1 1 (2) 1.00 in 2   = =     A Tempered steel: 2 2 3 2 (2) 0.75 in 16   = =     A Total: 2 1 2 1.75 in = + = A A A Total force to yield the mild steel: 3 3 1 1 (1.75)(50 10 ) 87.50 10 lb Y Y Y Y P P A A σ σ = ∴ = = × = × , Y P P > therefore, mild steel yields. Let 1 force carried by mild steel. P = 2 force carried by tempered steel. P = 3 3 1 1 1 (1.00)(50 10 ) 50 10 lb σ = = × = × P A 3 3 3 1 2 2 1 , 98 10 50 10 48 10 lb P P P P P P + = = − = × − × = × (a) 3 2 6 2 (48 10 )(14) (29 10 )(0.75) δ × = = × m P L EA 0.03090in. =  (b) 3 3 2 2 2 48 10 64 10 psi 0.75 σ × = = = × P A 64ksi =  Unloading: 3 6 (98 10 )(14) 0.02703 in. (29 10 )(1.75) δ × ′ = = = × PL EA (c) 0.03090 0.02703 δ δ δ ′ = − = − P m 0.00387in. = 
  • 129. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.113 The rigid bar ABC is supported by two links, AD and BE, of uniform 37.5 6-mm × rectangular cross section and made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = The magnitude of the force Q applied at B is gradually increased from zero to 260 kN. Knowing that 0.640 m, a = determine (a) the value of the normal stress in each link, (b) the maximum deflection of point B. SOLUTION Statics: 0: 0.640( ) 2.64 0 C BE AD M Q P P Σ = − − = Deformation: 2.64 , 0.640 A B a δ θ δ θ θ = = = Elastic analysis: 2 6 2 9 6 6 6 6 9 9 6 6 6 6 (37.5)(6) 225 mm 225 10 m (200 10 )(225 10 ) 26.47 10 1.7 (26.47 10 )(2.64 ) 69.88 10 310.6 10 (200 10 )(225 10 ) 45 10 1.0 (45 10 )(0.640 ) 28.80 10 AD A A A AD AD AD BE B B B BE A EA P L P A EA P L δ δ δ θ θ σ θ δ δ δ θ θ σ − − − = = = × × × = = = × = × = × = = × × × = = = × = × = × 9 128 10 BE BE P A θ = = × From Statics, 2.64 4.125 0.640 BE AD BE AD Q P P P P = + = + 6 6 6 [28.80 10 (4.125)(69.88 10 ] 317.06 10 θ θ = × + × = × Y θ at yielding of link AD: 6 9 250 10 310.6 10 AD Y σ σ θ = = × = × 6 6 6 3 804.89 10 (317.06 10 )(804.89 10 ) 255.2 10 N Y Y Q θ − − = × = × × = ×
  • 130. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.113 (Continued) (a) Since 3 260 10 , Y Q Q = × > link AD yields. 250 MPa AD σ =  6 6 3 (225 10 )(250 10 ) 56.25 10 N AD Y P Aσ − − = = × × = × From Statics, 3 3 4.125 260 10 (4.125)(56.25 10 ) BE AD P Q P = − = × − × 3 3 6 6 27.97 10 N 27.97 10 124.3 10 Pa 225 10 σ − = × × = = = × × BE BE BE P P A 124.3 MPa σ = BE  (b) 3 6 9 6 (27.97 10 )(1.0) 621.53 10 m (200 10 )(225 10 ) BE BE B P L EA δ − − × = = = × × × 0.622 mm B δ = ↓ 
  • 131. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.114 Solve Prob. 2.113, knowing that a = 1.76 m and that the magnitude of the force Q applied at B is gradually increased from zero to 135 kN. PROBLEM 2.113 The rigid bar ABC is supported by two links, AD and BE, of uniform 37.5 6-mm × rectangular cross section and made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = The magnitude of the force Q applied at B is gradually increased from zero to 260 kN. Knowing that 0.640 m, a = determine (a) the value of the normal stress in each link, (b) the maximum deflection of point B. SOLUTION Statics: 0: 1.76( ) 2.64 0 C BE AD M Q P P Σ = − − = Deformation: 2.64 , 1.76 A B δ θ δ θ = = Elastic Analysis: 2 6 2 9 6 6 6 6 9 9 6 6 6 6 (37.5)(6) 225 mm 225 10 m (200 10 )(225 10 ) 26.47 10 1.7 (26.47 10 )(2.64 ) 69.88 10 310.6 10 (200 10 )(225 10 ) 45 10 1.0 (45 10 )(1.76 ) 79.2 10 AD A A A AD AD AD BE B B B BE BE A EA P L P A EA P L δ δ δ θ θ σ θ δ δ δ θ θ σ − − − = = = × × × = = = × = × = × = = × × × = = = × = × = × 9 352 10 BE P A θ = = × From Statics, 2.64 1.500 1.76 BE AD BE AD Q P P P P = + = + 6 6 6 [73.8 10 (1.500)(69.88 10 ] 178.62 10 θ θ = × + × = × Y θ at yielding of link BE: 6 9 250 10 352 10 BE Y Y σ σ θ = = × = × 6 6 6 3 710.23 10 (178.62 10 )(710.23 10 ) 126.86 10 N Y Y Q θ − − = × = × × = × Since 3 135 10 N , Y Q Q = × > link BE yields. 250 MPa BE Y σ σ = =  6 6 3 (225 10 )(250 10 ) 56.25 10 N σ − = = × × = × BE Y P A 
  • 132. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.114 (Continued) From Statics, 3 1 ( ) 52.5 10 N 1.500 AD BE P Q P = − = × (a) 3 6 6 52.5 10 233.3 10 225 10 σ − × = = = × × AD AD P A 233 MPa σ = AD  From elastic analysis of AD, 3 6 751.29 10 rad 69.88 10 θ − = = × × AD P (b) 3 1.76 1.322 10 m B δ θ − = = × 1.322 mm B δ = ↓ 
  • 133. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.115∗ Solve Prob. 2.113, assuming that the magnitude of the force Q applied at B is gradually increased from zero to 260 kN and then decreased back to zero. Knowing that 0.640 m, a = determine (a) the residual stress in each link, (b) the final deflection of point B. Assume that the links are braced so that they can carry compressive forces without buckling. PROBLEM 2.113 The rigid bar ABC is supported by two links, AD and BE, of uniform 37.5 6-mm × rectangular cross section and made of a mild steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = The magnitude of the force Q applied at B is gradually increased from zero to 260 kN. Knowing that 0.640 m, a = determine (a) the value of the normal stress in each link, (b) the maximum deflection of point B. SOLUTION See solution to Problem 2.113 for the normal stresses in each link and the deflection of Point B after loading. 6 6 6 250 10 Pa 124.3 10 Pa 621.53 10 m AD BE B σ σ δ − = × = × = × The elastic analysis given in the solution to Problem 2.113 applies to the unloading. 6 3 6 6 6 317.06 10 260 10 820.03 10 317.06 10 317.06 10 Q Q Q θ − ′ ′ = × × ′ = = = × × × 9 9 6 6 9 9 6 6 6 310.6 10 (310.6 10 )(820.03 10 ) 254.70 10 Pa 128 10 (128 10 )(820.03 10 ) 104.96 10 Pa 0.640 524.82 10 m AD BE B σ θ σ θ δ θ − − − ′ = × = × × = × ′ = × = × × = × ′ ′ = = × (a) Residual stresses. 6 6 6 , res 250 10 254.70 10 4.70 10 Pa σ σ σ − ′ = − = × − × = − × AD AD AD 4.70MPa = −  6 6 6 , res 124.3 10 104.96 10 19.34 10 Pa σ σ σ ′ = − = × − × = × BE BE BE 19.34 MPa =  (b) 6 6 6 , 621.53 10 524.82 10 96.71 10 m δ δ δ − − − ′ = − = × − × = × B P B B 0.0967 mm = ↓ 
  • 134. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.116 A uniform steel rod of cross-sectional area A is attached to rigid supports and is unstressed at a temperature of 45 F. ° The steel is assumed to be elastoplastic with 36 Y σ = ksi and 6 29 10 psi. E = × Knowing that 6 6.5 10 / F, α − = × ° determine the stress in the bar (a) when the temperature is raised to 320 F, ° (b) after the temperature has returned to 45 F ° . SOLUTION Let P be the compressive force in the rod. Determine temperature change to cause yielding. 3 6 6 ( ) ( ) 0 36 10 ( ) 190.98 F (29 10 )(6.5 10 ) Y Y Y Y L PL L T L T AE E T E σ δ α α σ α − = − + Δ = − + Δ = × Δ = = = ° × × But 320 45 275 F ( ) Y T T Δ = − = ° > Δ (a) Yielding occurs. 36 ksi Y σ σ = − = −  Cooling: 6 6 3 ( T) 275 F ( ) 0 ( ) (29 10 )(6.5 10 )(275) 51.8375 10 psi P T P L L T AE P E T A δ δ δ α σ α − ′ Δ = ° ′ ′ ′ ′ ′ = = = − + Δ = ′ ′ ′ = = − Δ = − × × = − × (b) Residual stress: 3 3 res 36 10 51.8375 10 15.84 10 psi σ σ σ ′ = − − = − × + × = × Y 15.84 ksi 
  • 135. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.117 The steel rod ABC is attached to rigid supports and is unstressed at a temperature of 25 C. ° The steel is assumed elastoplastic, with E = 200 GPa and 250 MPa. y σ = The temperature of both portions of the rod is then raised to 150 C ° . Knowing that α = 6 11.7 10 / C, − × ° determine (a) the stress in both portions of the rod, (b) the deflection of point C. SOLUTION 6 2 6 2 500 10 m 0.150 m 300 10 m 0.250 m − − = × = = × = AC AC CB CB A L A L Constraint: 0 P T δ δ + = Determine ΔT to cause yielding in portion CB. ( ) AC CB AB AC CB AC CB AB AC CB PL PL L T EA EA L L P T L E A A α α − − = Δ   Δ = +     At yielding, 6 6 3 (300 10 )(2.50 10 ) 75 10 N Y CB Y P P A σ − = = = × × = × 3 9 6 6 6 ( ) 75 10 0.150 0.250 90.812 C (0.400)(200 10 )(11.7 10 ) 500 10 300 10 α − − −   Δ = +     ×   = + = °   × × × ×   AC CB Y Y AB AC CB L L P T L E A A Actual ΔT: 150 C 25 C 125 C ( )Y T ° − ° = ° > Δ Yielding occurs. For 3 ( ) , 75 10 N Y Y T T P P Δ > Δ = = × (a) 3 6 6 75 10 150 10 Pa 500 10 Y AC AC P A σ − − × = − = − = − × × 150 MPa AC σ = −  σ σ = − = − Y CB Y CB P A 250 MPa CB σ = −  (b) For ( ) , portion remains elastic. Y T T AC Δ > Δ / 3 6 6 9 6 ( ) (75 10 )(0.150) (0.150)(11.7 10 )(125) 106.9 10 m (200 10 )(500 10 ) Y AC C A AC AC P L L T EA δ α − − − = − + Δ × = − + × = × × × Since Point A is stationary, 6 / 106.9 10 m C C A δ δ − = = × 0.1069 mm C δ = → 
  • 136. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.118∗ Solve Prob. 2.117, assuming that the temperature of the rod is raised to 150°C and then returned to 25 C. ° PROBLEM 2.117 The steel rod ABC is attached to rigid supports and is unstressed at a temperature of 25 C. ° The steel is assumed elastoplastic, with 200 E = GPa and 250 Y σ = MPa. The temperature of both portions of the rod is then raised to 150 C. ° Knowing that 6 11.7 10 / C, α − = × ° determine (a) the stress in both portions of the rod, (b) the deflection of point C. SOLUTION 6 2 6 2 500 10 m 0.150 m 300 10 m 0.250 m − − = × = = × = AC AC CB CB A L A L Constraint: 0 P T δ δ + = Determine ΔT to cause yielding in portion CB. ( ) AC CB AB AC CB AC CB AB AC CB PL PL L T EA EA L L P T L E A A α α − − = Δ   Δ = +     At yielding, 6 6 3 (300 10 )(250 10 ) 75 10 N Y CB Y P P A σ − = = = × × = × 3 9 6 6 6 75 10 0.150 0.250 ( ) (0.400)(200 10 )(11.7 10 ) 500 10 300 10 90.812 C α − − −   ×   Δ = + = +     × × × ×     = ° AC CB Y Y AB AC CB L L P T L E A A Actual : 150 C 25 C 125 C ( ) Δ ° − ° = ° > Δ Y T T Yielding occurs. For 3 ( ) 75 10 N Y Y T T P P Δ > Δ = = × Cooling: ( ) ( ) ( ) 125 C α ′ Δ ′ ′ Δ = ° = + AC CB AC CB AB L L A A EL T T P 6 6 9 6 3 0.150 0.250 500 10 300 10 (200 10 )(0.400)(11.7 10 )(125) 103.235 10 N − − − × × × × = = × + Residual force: 3 3 3 res 103.235 10 75 10 28.235 10 N (tension) ′ = − = × − × = × Y P P P
  • 137. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.118∗ (Continued) (a) Residual stresses. 3 res 6 28.235 10 500 10 AC AC P A σ − × = = × 56.5 MPa AC σ =  3 res 6 28.235 10 300 10 CB CB P A σ − × = = × 9.41 MPa σ = CB  (b) Permanent deflection of point C. res δ = AC C AC P L EA 0.0424 mm C δ = → 
  • 138. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.119∗ For the composite bar of Prob. 2.111, determine the residual stresses in the tempered-steel bars if P is gradually increased from zero to 98 kips and then decreased back to zero. PROBLEM 2.111 Two tempered-steel bars, each 3 16 -in. thick, are bonded to a 1 2 -in. mild-steel bar. This composite bar is subjected as shown to a centric axial load of magnitude P. Both steels are elastoplastic with 6 29 10 E = × psi and with yield strengths equal to 100 ksi and 50 ksi, respectively, for the tempered and mild steel. The load P is gradually increased from zero until the deformation of the bar reaches a maximum value 0.04 m δ = in. and then decreased back to zero. Determine (a) the maximum value of P, (b) the maximum stress in the tempered-steel bars, (c) the permanent set after the load is removed. SOLUTION Areas: Mild steel: 2 1 1 (2) 1.00 in 2   = =     A Tempered steel: 2 2 3 (2) (2) 0.75 in 16   = =     A Total: 2 1 2 1.75 in = + = A A A Total force to yield the mild steel: 3 3 1 1 (1.75)(50 10 ) 87.50 10 lb σ σ = ∴ = = × = × Y Y Y Y P P A A P > PY; therefore, mild steel yields. Let 1 2 3 3 1 1 1 3 3 3 1 2 2 1 3 3 2 2 2 force carried by mild steel. force carried by tempered steel. (1.00)(50 10 ) 50 10 lb , 98 10 50 10 48 10 lb 48 10 64 10 psi 0.75 σ σ = = = = × = × + = = − = × − × = × × = = = × Y P P P A P P P P P P P A Unloading: 3 3 98 10 56 10 psi 1.75 P A σ × ′ = = = × Residual stresses. Mild steel: 3 3 3 1,res 1 50 10 56 10 6 10 psi σ σ σ − ′ = − = × − × = − × 6 ksi = − Tempered steel: 3 3 3 2,res 2 1 64 10 56 10 8 10 psi σ σ σ = − = × − × = × 8.00 ksi 
  • 139. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.120∗ For the composite bar in Prob. 2.111, determine the residual stresses in the tempered-steel bars if P is gradually increased from zero until the deformation of the bar reaches a maximum value 0.04 m δ = in. and is then decreased back to zero. PROBLEM 2.111 Two tempered-steel bars, each 3 16 -in. thick, are bonded to a 1 2 -in. mild-steel bar. This composite bar is subjected as shown to a centric axial load of magnitude P. Both steels are elastoplastic with 6 29 10 E = × psi and with yield strengths equal to 100 ksi and 50 ksi, respectively, for the tempered and mild steel. The load P is gradually increased from zero until the deformation of the bar reaches a maximum value 0.04 m δ = in. and then decreased back to zero. Determine (a) the maximum value of P, (b) the maximum stress in the tempered-steel bars, (c) the permanent set after the load is removed. SOLUTION For the mild steel, 3 2 1 1 1 6 1 (14)(50 10 ) (2) 1.00 in 0.024138 in 2 29 10 δ δ ×   = = = = =   ×   Y Y L A E For the tempered steel, 3 2 2 2 2 6 3 (14)(100 10 ) 2 (2) 0.75 in 0.048276 in. 16 29 10 δ δ ×   = = = = =   ×   Y Y L A E Total area: 2 1 2 1.75 in = + = A A A 1 2 δ δ δ < < Y m Y The mild steel yields. Tempered steel is elastic. Forces: 3 3 1 1 1 6 3 2 2 (1.00)(50 10 ) 50 10 lb (29 10 )(0.75)(0.04) 62.14 10 lb 14 δ δ = = × = × × = = = × Y m P A EA P L Stresses: 3 3 3 1 2 1 1 2 1 2 62.14 10 50 10 psi 82.86 10 psi 0.75 σ δ σ × = = = × = = = × Y P P A A Unloading: 3 112.14 64.08 10 psi 1.75 P A σ′ = = = × Residual stresses. 3 3 3 1,res 1 50 10 64.08 10 14.08 10 psi 14.08 ksi σ σ σ ′ = − = × − × = − × = − 3 3 3 2,res 2 82.86 10 64.08 10 18.78 10 psi 18.78 ksi σ σ σ ′ = − = × − × = × = 
  • 140. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.121∗ Narrow bars of aluminum are bonded to the two sides of a thick steel plate as shown. Initially, at 1 70 F, T = ° all stresses are zero. Knowing that the temperature will be slowly raised to T2 and then reduced to T1, determine (a) the highest temperature T2 that does not result in residual stresses, (b) the temperature T2 that will result in a residual stress in the aluminum equal to 58 ksi. Assume 6 12.8 10 / F α − = × ° a for the aluminum and 6 6.5 10 / F α − = × ° s for the steel. Further assume that the aluminum is elastoplastic, with E 6 10.9 10 = × psi and 58 Y σ = ksi. (Hint: Neglect the small stresses in the plate.) SOLUTION Determine temperature change to cause yielding. 3 6 6 ( ) ( ) ( )( ) 58 10 ( ) 844.62 F ( ) (10.9 10 )(12.8 6.5)(10 ) a Y s Y a s Y Y Y Y a s PL L T L T EA P E T A T E δ α α σ α α σ σ α α − = + Δ = Δ = = − − Δ = − × Δ = = = ° − × − (a) 2 1 ( ) 70 844.62 915 F = + Δ = + = ° Y Y T T T 915 F °  After yielding, ( ) ( ) Y a s L L T L T E σ δ α α = + Δ = Δ Cooling: ( ) ( ) a s P L L T L T AE δ α α ′ ′ ′ ′ = + Δ = Δ The residual stress is res ( )( ) Y Y a s P E T A σ σ σ α α ′ = − = − − Δ Set res ( )( ) Y Y Y a s E T σ σ σ σ α α = − − = − − Δ 3 6 6 2 (2)(58 10 ) 1689 F ( ) (10.9 10 )(12.8 6.5)(10 ) σ α α − × Δ = = = ° − × − Y a s T E (b) 2 1 70 1689 1759 F = + Δ = + = ° T T T 1759 F °  If 2 1759 F, T > ° the aluminum bar will most likely yield in compression.
  • 141. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.122∗ Bar AB has a cross-sectional area of 1200 mm2 and is made of a steel that is assumed to be elastoplastic with 200 GPa E = and 250 MPa. Y σ = Knowing that the force F increases from 0 to 520 kN and then decreases to zero, determine (a) the permanent deflection of point C, (b) the residual stress in the bar. SOLUTION 2 6 2 1200 mm 1200 10 m A − = = × Force to yield portion AC: 6 6 3 (1200 10 )(250 10 ) 300 10 N AC Y P Aσ − = = × × = × For equilibrium, 0. + − = CB AC F P P 3 3 3 300 10 520 10 220 10 N = − = × − × = − × CB AC P P F 3 9 6 3 3 6 6 (220 10 )(0.440 0.120) (200 10 )(1200 10 ) 0.293333 10 m 220 10 1200 10 183.333 10 Pa δ σ − − − × − = − = × × = × × = = × = − × CB CB C CB CB P L EA P A
  • 142. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.122∗ (Continued) Unloading: ( ) δ ′ ′ ′ − ′ = = − =   ′ + =     AC AC CB CB AC CB C AC BC CB AC P L P L F P L EA EA EA L L FL P EA EA EA 3 3 3 3 3 3 6 6 3 6 6 (520 10 )(0.440 0.120) 378.182 10 N 0.440 378.182 10 520 10 141.818 10 N 378.182 10 315.152 10 Pa 1200 10 141.818 10 118.182 10 Pa 1200 10 (3 σ σ δ − − × − ′ = = = × + ′ ′ = − = × − × = − × ′ × ′ = = = × × ′ × ′ = = − = − × × ′ = CB AC AC CB CB AC AC AC BC BC C FL P L L P P F P A P A 3 9 6 78.182)(0.120) 0.189091 10 m (200 10 )(1200 10 ) − = × × × (a) 3 3 3 , 0.293333 10 0.189091 10 0.1042 10 m δ δ δ − − − ′ = − = × − × = × C p C C 0.1042 mm =  (b) 6 6 6 , res 250 10 315.152 10 65.2 10 Pa σ σ σ′ = − = × − × = − × AC Y AC 65.2 MPa = −  6 6 6 , res 183.333 10 118.182 10 65.2 10 Pa σ σ σ′ = − = − × + × = − × CB CB CB 65.2 MPa = − 
  • 143. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.123∗ Solve Prob. 2.122, assuming that 180 a = mm. PROBLEM 2.122 Bar AB has a cross-sectional area of 1200 mm2 and is made of a steel that is assumed to be elastoplastic with 200 E = GPa and 250 Y σ = MPa. Knowing that the force F increases from 0 to 520 kN and then decreases to zero, determine (a) the permanent deflection of point C, (b) the residual stress in the bar. SOLUTION 2 6 2 1200 mm 1200 10 m A − = = × Force to yield portion AC: 6 6 3 (1200 10 )(250 10 ) 300 10 N AC Y P Aσ − = = × × = × For equilibrium, 0. + − = CB AC F P P 3 3 3 300 10 520 10 220 10 N CB AC P P F = − = × − × = − × 3 9 6 3 3 6 6 (220 10 )(0.440 0.180) (200 10 )(1200 10 ) 0.238333 10 m 220 10 1200 10 183.333 10 Pa δ σ − − − × − = − = × × = × × = = − × = − × CB CB C CB CB P L EA P A
  • 144. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.123∗ (Continued) Unloading: ( ) AC AC CB CB AC CB C AC BC CB AC P L P L F P L EA EA EA L L FL P EA EA EA δ ′ ′ ′ − ′ = = − =   ′ = + =     3 3 3 3 3 3 3 9 6 3 6 (520 10 )(0.440 0.180) 307.273 10 N 0.440 307.273 10 520 10 212.727 10 N (307.273 10 )(0.180) 0.230455 10 m (200 10 )(1200 10 ) 307.273 10 256.061 1200 10 CB AC AC CB CB AC C AC AC FL P L L P P F P A δ σ − − − × − ′ = = = × + ′ ′ = − = × − × = − × × ′ = = × × × ′ × ′ = = = × 6 3 6 6 10 Pa 212.727 10 177.273 10 P 1200 10 CB CB P A σ − × ′ − × ′ = = = − × × (a) 3 3 3 , 0.238333 10 0.230455 10 0.00788 10 m δ δ δ − − − ′ = − = × − × = × C p C C 0.00788 mm =  (b) 6 6 6 ,res 250 10 256.061 10 6.06 10 Pa AC AC AC σ σ σ′ = − = × − × = − × 6.06 MPa = −  6 6 6 ,res 183.333 10 177.273 10 6.06 10 Pa CB CB CB σ σ σ′ = − = − × + × = − × 6.06 MPa = −  
  • 145. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.124 Rod BD is made of steel 6 ( 29 10 psi) E = × and is used to brace the axially compressed member ABC. The maximum force that can be developed in member BD is 0.02P. If the stress must not exceed 18 ksi and the maximum change in length of BD must not exceed 0.001 times the length of ABC, determine the smallest-diameter rod that can be used for member BD. SOLUTION 3 0.02 (0.02)(130) 2.6 kips 2.6 10 lb = = = = × BD F P Considering stress: 3 18 ksi 18 10 psi σ = = × 2 2.6 0.14444 in 18 σ σ = ∴ = = = BD BD F F A A Considering deformation: (0.001)(144) 0.144 in. δ = = 3 2 6 (2.6 10 )(54) 0.03362 in (29 10 )(0.144) δ δ × = ∴ = = = × BD BD BD BD F L F L A AE E Larger area governs. 2 0.14444 in = A 2 4 (4)(0.14444) 4 π π π = ∴ = = A A d d 0.429in. = d 
  • 146. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.125 Two solid cylindrical rods are joined at B and loaded as shown. Rod AB is made of steel ( 200 GPa) E = and rod BC of brass ( 105 GPa). E = Determine (a) the total deformation of the composite rod ABC, (b) the deflection of point B. SOLUTION Rod AB: 3 30 10 N AB F P = − = − × 9 2 2 6 2 3 6 9 6 0.250 m 200 10 GPa (30) 706.85 mm 706.85 10 m 4 (30 10 )(0.250) 53.052 10 m (200 10 )(706.85 10 ) π δ − − − = = × = = = × × = = − = − × × × AB AB AB AB AB AB AB AB L E A F L E A Rod BC: 3 30 40 70 kN 70 10 N BC F = + = = × 9 2 3 2 3 2 3 6 9 3 0.300 m 105 10 Pa (50) 1.9635 10 mm 1.9635 10 m 4 (70 10 )(0.300) 101.859 10 m (105 10 )(1.9635 10 ) π δ − − − = = × = = × = × × = = − = − × × × BC BC BC BC BC BC BC BC L E A F L E A (a) Total deformation: 6 tot 154.9 10 m δ δ δ − = + = − × AB BC 0.1549 mm = −  (b) Deflection of Point B. B BC δ δ = 0.1019 mm B δ = ↓ 
  • 147. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.126 Two solid cylindrical rods are joined at B and loaded as shown. Rod AB is made of steel 6 ( 29 10 = × E psi), and rod BC of brass 6 ( 15 10 psi). E = × Determine (a) the total deformation of the composite rod ABC, (b) the deflection of point B. SOLUTION Portion AB: 3 2 2 2 6 3 3 6 40 10 lb 40 in. 2 in. (2) 3.1416 in 4 4 29 10 psi (40 10 )(40) 17.5619 10 in. (29 10 )(3.1416) AB AB AB AB AB AB AB AB AB P L d A d E P L E A π π δ − = × = = = = = = × × = = = × × Portion BC: 3 2 2 2 6 3 3 6 20 10 lb 30 in. 3 in. (3) 7.0686 in 4 4 15 10 psi ( 20 10 )(30) 5.6588 10 in. (15 10 )(7.0686) BC BC BC BC BC BC BC BC BC P L d A d E P L E A π π δ − = − × = = = = = = × − × = = = − × × (a) 6 6 17.5619 10 5.6588 10 AB BC δ δ δ − − = + = × − × 3 11.90 10 in. δ − = × ↓  (b) B BC δ δ = − 3 5.66 10 in. B δ − = × ↑ 
  • 148. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.127 The uniform wire ABC, of unstretched length 2l, is attached to the supports shown and a vertical load P is applied at the midpoint B. Denoting by A the cross-sectional area of the wire and by E the modulus of elasticity, show that, for , l δ  the deflection at the midpoint B is 3 δ = P l AE SOLUTION Use approximation. sin tan l δ θ θ ≈ ≈ Statics: 0 : 2 sin 0 θ Σ = − = Y AB F P P 2sin 2 θ δ = ≈ AB P Pl P Elongation: 2 2 AB AB P l Pl AE AE δ δ = = Deflection: From the right triangle, 2 2 2 2 2 ( ) AB l l l δ δ δ + = + = 2 2 2 AB AB l l δ δ + + − 3 1 2 1 2 2 AB AB AB l l l Pl AE δ δ δ δ   = + ≈     ≈ 3 3 3 Pl P l AE AE δ δ ≈ ∴ ≈ 
  • 149. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.128 The brass strip AB has been attached to a fixed support at A and rests on a rough support at B. Knowing that the coefficient of friction is 0.60 between the strip and the support at B, determine the decrease in temperature for which slipping will impend. SOLUTION Brass strip: 6 105 GPa 20 10 / C E α − = = × ° 0: 0 Σ = − = = y F N W N W 0: 0 ( ) 0 μ μ μ μ δ α α α Σ = − = = = = − + Δ = Δ = = x F P N P W mg PL P mg L T T EA EA EA Data: 2 6 2 2 9 0.60 (20)(3) 60 mm 60 10 m 100 kg 9.81 m/s 105 10 Pa A m g E μ − = = = = × = = = × 9 6 6 (0.60)(100)(9.81) (105 10 )(60 10 )(20 10 ) T − Δ = × × × 4.67 C T Δ = ° 
  • 150. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.129 Members AB and CD are 1 8 1 -in.-diameter steel rods, and members BC and AD are 7 8 -in.-diameter steel rods. When the turnbuckle is tightened, the diagonal member AC is put in tension. Knowing that 6 29 10 E = × psi and 4 = h ft, determine the largest allowable tension in AC so that the deformations in members AB and CD do not exceed 0.04 in. SOLUTION 2 2 2 6 3 0.04 in. 4ft 48 in. (1.125) 0.99402 in 4 4 (29 10 )(0.99402)(0.04) 24.022 10 lb 48 AB CD CD CD CD CD CD CD CD CD CD CD h L A d F L EA EA F L δ δ π π δ δ = = = = = = = = = × = = = × Use joint C as a free body. 4 5 0: 0 5 4 Σ = − = ∴ = y CD AC AC CD F F F F F 3 3 5 (24.022 10 ) 30.0 10 lb 4 = × = × AC F 30.0 kips = AC F 
  • 151. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.130 The 1.5-m concrete post is reinforced with six steel bars, each with a 28-mm diameter. Knowing that 200 s E = GPa and 25 c E = GPa, determine the normal stresses in the steel and in the concrete when a 1550-kN axial centric force P is applied to the post. SOLUTION Let portion of axial force carried by concrete. portion carried by the six steel rods. = = c s P P ( ) c c c c c c s s s s s s c s c c s s c c s s P L E A P E A L P L E A P E A L P P P E A E A L P L E A E A δ δ δ δ δ δ ε = = = = = + = + − = = + 2 2 3 2 3 2 2 2 3 3 2 3 2 3 6 9 3 9 3 6 6 (28) 3.6945 10 mm 4 4 3.6945 10 m (450) 3.6945 10 4 4 155.349 10 mm 153.349 10 m 1.5 m 1550 10 335.31 10 (25 10 )(155.349 10 ) (200 10 )(3.6945 10 ) s s c c s A d A d A L π π π π ε − − − − − = = = × = × = − = − × = × = × = × = = × × × + × × 9 6 6 (200 10 )(335.31 10 ) 67.1 10 Pa σ ε − = = × × = × s s E σs = 67.1 MPa  9 6 6 (25 10 )( 335.31 10 ) 8.38 10 Pa σ ε − = = × − × = × c c E σc = 8.38 MPa 
  • 152. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.131 The brass shell 6 ( 11.6 10 / F) α − = × ° b is fully bonded to the steel core 6 ( 6.5 10 / F). α − = × ° s Determine the largest allowable increase in temperature if the stress in the steel core is not to exceed 8 ksi. SOLUTION Let axial force developed in the steel core. s P = For equilibrium with zero total force, the compressive force in the brass shell is . s P Strains: ( ) ( ) s s s s s s b b b b P T E A P T E A ε α ε α = + Δ = − + Δ Matching: s b ε ε = ( ) ( ) s s s b s s b b P P T T E A E A α α + Δ = − + Δ 1 1 ( )( ) s b s s s b b P T E A E A α α   + = − Δ     (1) 2 2 (1.5)(1.5) (1.0)(1.0) 1.25 in (1.0)(1.0) 1.0 in = − = = = b s A A 6 3 3 5.1 10 / F (8 10 )(1.0) 8 10 lb b s s s s P A α α σ − − = × ° = = × = × 9 1 6 6 1 1 1 1 87.816 10 lb (29 10 )(1.0) (15 10 )(1.25) s s b b E A E A − − + = + = × × × From (1), 9 3 6 (87.816 10 )(8 10 ) (5.1 10 )( ) T − − × × = × Δ 137.8 F Δ = ° T 
  • 153. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.132 A fabric used in air-inflated structures is subjected to a biaxial loading that results in normal stresses 120 x σ = MPa and 160 z σ = MPa. Knowing that the properties of the fabric can be approximated as E = 87 GPa and v = 0.34, determine the change in length of (a) side AB, (b) side BC, (c) diagonal AC. SOLUTION 6 6 6 6 6 9 6 6 3 9 120 10 Pa, 0, 160 10 Pa 1 1 ( ) [120 10 (0.34)(160 10 )] 754.02 10 87 10 1 1 ( ) [ (0.34)(120 10 ) 160 10 ] 1.3701 10 87 10 σ σ σ ε σ σ σ ε σ σ σ − − = × = = × = − − = × − × = × × = − − + = − × + × = × × x y z x x y z z x y z v v E v v E (a) 6 ( ) (100 mm)(754.02 10 ) δ ε − = = × AB x AB 0.0754 mm =  (b) 6 ( ) (75 mm)(1.3701 10 ) δ ε − = = × BC z BC 0.1028 mm =  Label sides of right triangle ABC as a, b, and c. 2 2 2 c a b = + Obtain differentials by calculus. 2 2 2 = + = + c dc a da b db a b dc da db c c But 2 2 100 mm, 75 mm, (100 75 ) 125 mm 0.0754 mm 0.1370 mm δ δ = = = + = = = = = AB BC a b c da db (c) 100 75 (0.0754) (0.1028) 125 125 δ = = + AC dc 0.1220 mm = 
  • 154. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.133 An elastomeric bearing ( 0.9 G = MPa) is used to support a bridge girder as shown to provide flexibility during earthquakes. The beam must not displace more than 10 mm when a 22-kN lateral load is applied as shown. Knowing that the maximum allowable shearing stress is 420 kPa, determine (a) the smallest allowable dimension b, (b) the smallest required thickness a. SOLUTION Shearing force: 3 22 10 N P = × Shearing stress: 3 420 10 Pa τ = × 3 3 2 3 3 2 22 10 52.381 10 m 420 10 52.381 10 mm (200 mm)( ) P P A A A b τ τ − = ∴ = × = = × × = × = (a) 3 52.381 10 262 mm 200 200 A b × = = = 262 mm = b  3 3 6 420 10 466.67 10 0.9 10 G τ γ − × = = = × × (b) But 3 10 mm 21.4 mm 466.67 10 a a δ δ γ γ − = ∴ = = = × 21.4 mm = a 
  • 155. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.134 Knowing that 10 kips, P = determine the maximum stress when (a) 0.50 in., = r (b) 0.625 in. r = SOLUTION 3 10 10 lb 5.0 in. 2.50 in. 5.0 2.00 2.50 P D d D d = × = = = = 2 min 3 (2.50) 1.875 in 4 A dt   = = =     (a) 0.50 0.50 in. 0.20 2.50 r r d = = = From Fig. 2.60b, 1.94 K = 3 3 max min (1.94)(10 10 ) 10.35 10 psi 1.875 KP A σ × = = = × 10.35 ksi  (b) 3 3 max min 0.625 0.625 in. 0.25 1.82 2.50 (1.82)(10 10 ) 9.71 10 psi 1.875 r r K d KP A σ = = = = × = = = × 9.71 ksi 
  • 156. PROPRIETARY MATERIAL. © 2012 The McGraw-Hill Companies, Inc. All rights reserved. No part of this Manual may be displayed, reproduced, or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. A student using this manual is using it without permission. PROBLEM 2.135 The uniform rod BC has a cross-sectional area A and is made of a mild steel that can be assumed to be elastoplastic with a modulus of elasticity E and a yield strength . y σ Using the block-and-spring system shown, it is desired to simulate the deflection of end C of the rod as the axial force P is gradually applied and removed, that is, the deflection of points C and C′ should be the same for all values of P. Denoting by μ the coefficient of friction between the block and the horizontal surface, derive an expression for (a) the required mass m of the block, (b) the required constant k of the spring. SOLUTION Force-deflection diagram for Point C or rod BC. For max σ δ δ σ < = = = = = Y Y C C Y Y P P A PL EA P EA L P P A Force-deflection diagram for Point C′ of block-and-spring system. 0 : 0 Σ = − = = y F N mg N mg 0: 0 Σ = − = = x f f F P F P F If block does not move, i.e., or , μ μ μ < = < f F N mg P mg then or c c P P k K δ δ ′ ′ = = If P = μ mg, then slip at occurs. μ = = m P F mg If the force P is the removed, the spring returns to its initial length. (a) Equating PY and Fmax, σ σ μ μ = = Y Y A A mg m g  (b) Equating slopes, EA k L = 