Experimental Stress Analysis and Optimization of Connecting Rod

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 03 | Mar -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 1681
Experimental Stress Analysis and Optimization of Connecting Rod
Ghadoje Sagar S1, Gite Hemant S2, Gawali Dipak P3 , Gayke Dnyaneshwar S.4
Mechanical Engineering 1,2,3,4
, SND COE & RC, Yeola1,2,3,4
Email: ghadoje4engg@gmail.com1
,hemant.gite95@gmail.com2
dipakgawali59@gmail.com3
, gaikednyan025@gmail.com4
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Abstract - The main objective of this study was to explore
weight and cost reduction Opportunities for a production
forged steel connecting rod. This has entailed performing a
detailed load analysis. Therefore, this study hasdealtwithtwo
subjects, first, stress analysis of the connecting rod, and
second, optimization for weight and cost. Itistheconclusionof
this study that the connecting rod can be designed and
optimized under a load range comprising tensile load
corresponding to 360o crank angle at the maximum engine
speed as one extreme load, and compressive load
corresponding to the peak gas pressure as the other extreme
load.
Key Words: Connecting Rod, Finite Element Analysis,
Stress, optimization, Design .
1. INTRODUCTION
Connecting rod is the intermediate link between the piston
and the crank. And is responsible to transmit the push and
pull from the piston pin to crank pin, thus converting the
reciprocating motion of the piston to rotary motion of the
crank. Connecting rods manufactured by forging eitherfrom
wrought steel or powdered metal. They could also be cast.
However, castings could have blow-holes which are
detrimental from durability and fatigue points of view. The
fact that forgings produce blow-hole-free and better rods
gives them an advantage over cast rods. Betweentheforging
processes, powder forged or drop forged, each process has
its own pros and cons. Powder metal manufactured blanks
have the advantage of being near net shape, reducing
material waste. However, the cost of the blank is high due to
the high material cost and sophisticated manufacturing
techniques. With steel forging, the material is inexpensive
and the rough part manufacturing process is cost effective.
Bringing the part to final dimensions under tight tolerance
results in high expenditure for machining as the blank
usually contains more excess material.
The connecting rod can be designed and optimized under a
load range, corresponding to 360o crank angle at the
maximum engine speed as one extreme load, and
compressive load corresponding to the peak gas pressure as
the other extreme load. In this project we are going tomodel
the connecting rod using CAD tool (CATIA V5) to do static
structural analysis for static load to check stresses,
deformation, strain locations & second part of project is
topology optimization for mass reduction without much
altering strength using CAE tool (Ansys). Experimental is
carried out by machining existing connecting rod as per
topological optimization using EDM. Strain gauge will be
mounted at high strain location on the connecting rod
defined from FEA to get deformation while testing on UTM.
2. OBJECTIVES
(1) Modeling current connecting rod.
(2) Analyzing for stresses and deformation.
(3) Topological optimization for the model.
(4) Analyzing for stresses and deformation on optimized
model.
(5) Results from topological optimization will be
implemented on existing model.
(6) Machining the existing connecting rod as per
optimization result.
(7) Mounting strain gauge on same portion.
(8) Preparing fixtures to hold connecting rod for
experimental testing.
(9) Correlating results of both CAE and experimental
3. PROBLEM STATEMENT
Connecting rods are widely used in variety of engine.
Currently, connecting rods contains excessmaterial,leadsto
increase in weight of the vehicle. Directly affects the mileage
and cost. In this thesis, modeling existing connecting rod in
CAD software and analyzing it for induced stresses and
deformation in CAE software. Then using Topology
optimization material will be removed. Again, analysis will
be done on optimized model for stresses and deformation.It
is also tested experimentally and results were correlated it
with analysis results.
3.1 Engine & Transmission Specification
 Engine: Cummins 6BTAA, DI Turbocharged, with
Viscous fan
 Emission Norms: BSIII
 Engine Cylinders: 6
 Displacement (cc): 5883

 Max Power: 135 bhp @ 2400 rpm
 Max Torque: 490 Nm @ 1400-1600rpm
 Transmission: Manual
 Clutch: 352 mm dia., Spicer Puller type
 Gearbox: 6speed
 Fuel: Diesel
 Fuel Tank: 250 Litres
Fig -1 : Existing component of TATA1612 heavy vehicle
4. MODELING OF CONNECTING ROD
Dimensions of cross-section of the connecting rod.
Dimensions of the crankpin at the big end and the piston pin
at the
small end.
Size of bolts for securing the big end cap.
Thickness of the big end cap.
As per existing connecting rod (i.e, TATA 1612 vehicle
connecting rod),
Small hole inner dia. = 35mm
Small hole outer dia. = 50mm
Big hole inner dia. = 60mm
Big hole outer dia. = 80mm
Thickness = 35mm
Center to center distance = 225mm
Spine width = 30mm
Spine thickness = 21mm
Slot on spine length107x width13x depth7mm
Bolt dia. = 14mm
Length = 67mm
Head dia. = 21mm
Length = 8mm
Washer outer dia. = 28mm
Inner dia. = 14mm
Length = 4mm.
Fig - 2 : 2D Drafting of Connecting Rod
Fig - 3 : CAD Model of Connecting Rod
4.1 Calculation
Calculations:
We know,
Crank throw (t’) = 64mm
Dia. of Bore (d) calculate as follows,
Pressure (Pb) exerted due to combustion on piston head,
Pressure (Pb) = 855947.1 N/m2
Therefore,
Force (F) = Pressure * C/S Area
= 855947.1*π/4*(98.76*10-3)2
= 6556.64 ~ 6560N.
5. FINITE ELEMENT METHOD
5.1 Mesh Generation:
It is a numerical technique for findingapproximatesolutions
to boundary value problems for partial differential
equations. It is also referred to as finite element analysis
(FEA). FEM subdivides a large problemintosmaller,simpler,
parts, called finite elements. The simple equations that
model these finite elements are then assembled into a larger
system of equations that models the entire problem. FEM
then uses variational methodsfromthecalculusofvariations

to approximate a solution by minimizing an associated error
function.
Fig- 4: Discretized Model
Element type- Wedge
No. of Elements- 82105
No. of Nodes- 52748
6. FEA PROCESSING
6.1 Pre Processing
The values of young’s modulus, poisons ratio, density, yield
strength for steel are taken from material library of the FEA
PACKAGE.
Material- Structural Steel
Young’s Modulus- 200 GPa
Poisons Ratio- 0.3
Density- 7850 kg/m^3
Yield Strength- 250 MPa.
The nodes around the connecting rod holes have a rigid
element connecting them to the centre of the hole which has
of its degree of freedom fixed. The element which is used to
fix connecting rod and crank shaft is fixed and usedasa rigid
element. Fig shows connecting rod is fixed at crank end and
load is applied from the piston end.
Fig - 5: Boundary Condition
6.2 Post Processing
Model acceptance criteria: the maximum von-Mises stress
must be less than the material yieldstrengthfortheduration
of the component. The deflection is considered and the
maximum Von-Mises stress must be less than the yield
strength for abuse load case.
Fig- 6: Von - Mises stress of existing model
Fig- 7: Deformation of existing model
7. OPTIMIZATION
7.1 Topology Optimization:
Topology optimization is a mathematical approach that
optimizes material layout within a given design space, for a
given set of loads and boundary conditions such that the
resulting layout meets a prescribed set of performance
targets
There are three kinds of structure optimization,
Size Optimization
Shape Optimization
Topology Optimization
Three optimization methods correspond to the three stages
of the product design process, namely the detailed design,
basic design and conceptual design. Size optimization keeps
the structural shape and topology structure invariant, to

optimize the various parameters of structure, such as
thickness, section size of beam, material’s properties; shape
optimization maintains the topologystructure,tochange the
boundary of structure and shape, seek the most suitable
structure boundary situation and shape; topology
optimization is to find the optimal path of material’s
distribution in a continuous domain which meet the
displacement and stress conditions in structure, make a
certain performance optimal. Thus, compared to size and
shape optimization, topology optimization with more
freedom degree and greaterdesignspace,itsgreatestfeature
is under uncertain structural shape, according to the known
boundary condition and a given load to determine the
reasonable structure, both for the conceptual design of new
products and improvement design for existingproducts, itis
the most promising aspect of structural optimization.
Fig-8: 2D drafting of optimized model
Fig- 9: Meshing for optimized model
Element type- Wedge
No. of Elements- 10531
No. of Nodes- 5373
7.2 Boundary Conditions:
Fig - 10: Boundary condition
7.3 Von Misses:
Fig-11: Von- Mises stress of Optimized model
8. EXPERIMENTAL ANALYSIS OF CONNECTING
ROD
8.1 Installation of Strain Gauge:
The proper installation of a strain gauge requires a number
of distinct steps. First, the surface must be properly cleaned
and polished. After this, the gauge is installed and lead wires
are connected. Finally, a protective coating is applied to
protect the gauge.
8.2 Cleaning procedure:
The surface where the gauge is to be installed should be
cleaned no more than 30 minutes prior to the installation of
the gauge. If more time has elapsed, repeat this procedure.
1. Degrease the surface of interest with a small amount of
isopropyl alcohol and a Kim Wipe. Take care not to
contaminate the cleaned surfaces from this point on.
2. Apply one or two drops of M-prep Conditioner A to the
cleaned area and lightly sand with 400 grit or higher emery
paper to remove the paint in the gauge area. Use sand paper
carefully to prevent damage to surface.

3. Use a Kim Wipe to remove any loose particles from the
surface. Continue wiping until no trace of paint can be seen
on the Kim Wipe.
4. Wet the exposed area with one or two drops of M-prep
Conditioner A and lightly scrub the area with a Kim Wipe.
Finish by using a fresh wipe and making a single stroke
across the surface.
5. Wet the exposed area with one or two drops of M-prep
Neutralizer 5A and lightly scrub the area with a Kim Wipe.
Again finish by using a fresh wipe and makinga singlestroke
across the cleaned surface.
Fig-12: Experimental Set-up
Deflection measured and found on optimized 0.0174 mm
model is very less.
9. RESULT AND CONCLUSIONS
From results of finite element analysis it is observedthatthe
maximum stress value is within the safety limit. There is a
great potential to optimize, this safety limit which can be
done by removing material from low stressed region thus
optimizing its weight without affecting its structural
behavior. The maximum displacementvalueisalsoveryless.
So, the material from low stressed region is can be removed
without affecting its strength and is within the yield
strength.
 Von-mises stress found on existing (17.993MPa)
and optimized (27.477 MPa) components are
within the material yield strength.
 Deflection measured and found on existing
(0.011mm) and optimized (0.0174mm) model is
very less.
 With this topological optimization weight reduced
from existing (2.351kg) to optimized (2.240kg)
component
 Von-mises stress found on existing (17.993MPa)
and optimized (27.477 MPa) components are
within the material yield strength.
 Deflection measured and found on existing
(0.011mm) and optimized (0.0174mm) model is
very less.
10. REFERENCES
[1] Kuldeep B, Arun L.R,MohammedFaheem,“Analysis
and optimization of connecting rod using alfasic
composites”, International Journal of Innovative
Research in Science, Engineering and Technology,
Vol-2, Issue-6, June 2013
[2] AbhinavGautam, K Priya Ajit, “ Static Stress
Analysis of Connecting Rod Using Finite Element
Approach”, IOSR Journal of Mechanical and Civil
Engineering (IOSR-JMCE) e-ISSN: 2278-1684, p-
ISSN: 2320-334X, Volume 10, Issue 1 (Nov. - Dec.
2013), pp. 47-51
[3] Vivek.c.pathade, Bhumeshwar Patle, Ajay N. Ingale
”Stress Analysis of I.C. Engine Connecting Rod by
FEM”, International Journal of Engineering and
Innovative Technology, Vol-1, Issue-3, pp-12-15,
March 2012.
[4] J.D.Ramani, Sunil Shukla, Pushpendra Kumar
Sharma, “FE-Analysis of Connecting Rod of
I.C.Engine by Using Ansys for Material
Optimization” Int. Journal of Engineering Research
and Applications www.ijera.com ISSN : 2248-9622,
Vol. 4, Issue 3( Version 1), March 2014, pp.216-220

Experimental Stress Analysis and Optimization of Connecting Rod

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Experimental Stress Analysis and Optimization of Connecting Rod