ENGINEERING MECHANICS PPT
- 1. CENTER FOR INVENTION, INNOVATION, INCUBATION & TRAINING (CIIIT) Government College of Engineering Chandrapur Name of Students : 1. Vivek Atalkar 2. Aniket Awate 3. Abhishek Bawane 4. Sumit Dhodare 5. Pranay Ghatode Department of Mechanical Engineering Guided by : Atul Bihure, Arpit Agrawal
- 3. CONTENTS Introduction to Mechanics Simple Lifting Machine Kinematics of Machine Loads & Beam Stress Strain Curve
- 4. Introduction to Mechanics It is a branch of engineering which deals with the behavior of a body when the body is at rest or in motion. What is Mechanics?
- 5. Mechanics Statics (Body At Rest) Dynamics (Body In Motion) Kinematics (The Forces Which Cause motion Are Not Considered) Kinetics (The Forces Which Caused Motion are Considered) CLASSIFICATION OF MECHANICS
- 6. Statics : It deals with the study of forces acting on machines parts when the body is at rest or in equilibrium position. Dynamics : It deals with the study of forces acting on machine parts when the body is in motion.
- 7. Kinetics : It deals with the study of forces acting on machines parts including inertia forces (inertia forces are the combine effect of the mass & the motion of the parts). Ex: Friction, Torque, etc. Kinematics : It deals with the study of relative motion of machine parts only. It is not concerned with the forces acting on machine parts.
- 8. Basic terms used in mechanics Some Basic Terms Used In Mechanics Force: Force is an external agent capable of changing a body's state of rest or motion. Its SI unit is Newton. Displacement: It is defined as the shortest distance covered by a body/particle in the specified direction. Velocity: The rate of change of displacement with respect to time is defined as velocity. Acceleration: It is the rate of change of velocity with respect to time.
- 9. Basic terms used in mechanics Momentum: The product of mass and velocity is called momentum. Thus Momentum = Mass × Velocity Torque: It is a measure of the force that can cause an object to rotate about an axis.
- 10. Simple lifting machine Simple lifting machine is the device used to lift a heavy load by applying comparatively smaller force or effort. Mechanical Advantage: It is the ratio of load lifted by a machine to effort applied. M.A. = Mechanical Advantage (M.A.) is always greater than 1. Load Effort
- 11. Types of Simple Lifting Machine 1. Pulley 2. Screw 3. Lever Pulley: A pulley is a simple machine that consists of a rope and grooved wheel. The rope fits into the groove in the wheel, and pulling on the rope turns the wheel. Pulleys are generally used to lift objects, especially heavy objects. Application: Shipping & Marine used, Industry, Elevators, etc. Simple lifting machine
- 12. Simple lifting machine Screw: A screw jack is used to lift a heavy load by applying smaller effort. It consists of a screw, fitted in a nut, which forms the body of the jack and a screw head to which a handle is attached. The load is kept on the screw head and effort is applied by the handle. Application: Lifting cars and trucks, lifting machinery for assembly purpose, etc.
- 13. Simple lifting machine Lever: A lever is a simple machine made of a rigid beam and a fulcrum. The effort (input force) and load (output force) are applied to either end of the beam. The fulcrum is the point on which the beam pivots. Application: See-saw, scissors, plier, etc.
- 14. Kinematics of Machine Kinematics of Machine As we seen earlier, Kinematics of Machine deals with the study of relative motion of machine parts only. It is not concerned with the forces acting on machine parts. It is the study from geometric point of view to know the displacement, velocity & acceleration of a part of a machines.
- 15. Mechanism : A mechanism is made up of no. of resistant bodies out of which some may have motion relative to the others. The primary function of mechanism is to modify or transmit motion. Machine : Machine is made up of no. of mechanism. Machines are used to transform some available form of energy or motion into another form which is necessary for the performance of specified operation. They must transfer both forces and motions.
- 16. KinematicLink A resistant body which is a part of a machine and has motion relative to other connected parts is termed as a link or an element. It is also called as Kinematic Link. Types of Kinematic Link : i. Rigid link ii. Flexible link
- 17. 1 Kinematic chain Kinematic Chain : It is the combination of no. of kinematics link such that first link is joint with last link in which the relative motion of link is possible. 2 3 1 4
- 18. Four Bar Chain / Mechanism Four bar chain or mechanism is made up of four links in which one link is fixed and other three links having relative motion to each other. It converts rotary motion into oscillatory motion. Four bar mechanism
- 19. Four bar mechanism Crank Rocker / Lever Connecting Rod
- 20. Single Slider Crank Chain / Mechanism A slider crank mechanism converts the reciprocating motion of the slide to the rotary motion of the crank and vice versa. However when it is used as an automobile engine by adding the valve mechanism it becomes a machine which converts available energy into desired energy. Examples: Steam Engine, Reciprocating pump Single slider crank mechanism
- 22. Beams & Loads Beam : Structural member which carries the transverse load or force (force which acting perpendicular to the longitudinal axis of structure. Type of Beams: Simply supported beam Cantilever beam Overhanging beam Fixed beams Continuous beam
- 23. beams Simply Supported Beam Application : Bridges, beams in buildings, and beds of machine tools.
- 24. beams Cantilever Beam Application : Street signs, airplane wings, shelves, fan blades, and some bridges are all examples of cantilevers
- 25. beams Overhanging Beam Application : An overhanging beam is used where it is not practical to provide a support to the beam at one end.
- 26. beams Fixed Beam Application : Fixed beams provide sturdiness to the structure. They are used to withstand both horizontal and vertical forces. Installing them in a sloppy roof of a house is how you can put them to the best use. All of the strength of such a structural element comes from two load-bearing fixed ends.
- 27. beams Continuous Beam Application : Continuous beams are used in bridges, multi-story buildings, complex roof structures, and other construction projects.
- 28. lOADS Loads The external force acting on the section or member. For study of shear force and bending moment, we classify the load into following manner:- 1. Point load or concentrated load 2. Uniform distributed load 3. Uniformly varying load
- 29. lOADS Point load or concentrated load The load which act on a single point of any section or member, although in practice it must really be distributed on very small area.
- 30. lOADS Uniform distributed load The load which is spread over a beam or section uniformly along the length. It is expressed as w N/m. It is represented by u.d.l.
- 31. lOADS Uniformly varying load The load which is spread on the section of member such that rate of loading varies from the point to point as shown in the below figure in which load at one section is zero and increase uniformly to the other end. It is also known as triangular load.
- 33. REGIONS IN STRESS STRAIN CURVE Typical regions that can be observed in a stress-strain curve are: Elastic region Yielding Plastic region Strain Hardening Necking and Failure
- 34. Elastic Region : If the specimen returns to its original length when the load acting on it is removed, it is said to response elastically. Yielding and Plastic Deformation : A slight increase in stress above the elastic limit will result in permanent deformation. This behavior is called yielding. The stress that causes yielding is called yield stress sy The deformation that occurs is called plastic deformation.
- 35. Strain Hardening : A further load can be applied to the specimen, resulting in a cure that rises continuously but becomes flatter until it reaches a maximum stress referred to as ultimate stress, Su The rise in the curve is called Strain Hardening.
- 36. Necking and failure: After the ultimate stress, the cross-sectional area begins to decrease in a localized region of the specimen, instead of over its entire length. The load (and stress) keeps dropping until the specimen reaches the fracture point.
- 38. Thank You