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# Note for Machine Dynamics - MD By Engineering Kings

• Machine Dynamics - MD
• Note
• Veer Surendra Sai University Of Technology VSSUT -
• Mechanical Engineering
• 95 Views
Engineering Kings
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Machine Dynamics – I Lecture Note By Er. Debasish Tripathy ( Assist. Prof. Mechanical Engineering Department, VSSUT, Burla, Orissa,India) Syllabus: Module – I 1. Mechanisms: Basic Kinematic concepts & definitions, mechanisms, link, kinematic pair, degrees of freedom, kinematic chain, degrees of freedom for plane mechanism, Gruebler’s equation, inversion of mechanism, four bar chain & their inversions, single slider crank chain, double slider crank chain & their inversion.(8) Module – II 2. Kinematics analysis: Determination of velocity using graphical and analytical techniques, instantaneous center method, relative velocity method, Kennedy theorem, velocity in four bar mechanism, slider crank mechanism, acceleration diagram for a slider crank mechanism, Klein’s construction method, rubbing velocity at pin joint, coriolli’s component of acceleration & it’s applications. (12) Module – III 3. Inertia force in reciprocating parts: Velocity & acceleration of connecting rod by analytical method, piston effort, force acting along connecting rod, crank effort, turning moment on crank shaft, dynamically equivalent system, compound pendulum, correction couple, friction, pivot & collar friction, friction circle, friction axis. (6) 4. Friction clutches: Transmission of power by single plate, multiple & cone clutches, belt drive, initial tension, Effect of centrifugal tension on power transmission, maximum power transmission(4). Module – IV 5. Brakes & Dynamometers: Classification of brakes, analysis of simple block, band & internal expanding shoe brakes, braking of a vehicle, absorbing & transmission

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dynamometers, prony brakes, rope brakes, band brake dynamometer, belt transmission dynamometer & torsion dynamometer.(7) 6. Gear trains: Simple trains, compound trains, reverted train & epicyclic train. (3) Mechanism and Machines Mechanism: If a number of bodies are assembled in such a way that the motion of one causes constrained and predictable motion to the others, it is known as a mechanism. A mechanism transmits and modifies a motion. Machine: A machine is a mechanism or a combination of mechanisms which, apart from imparting definite motions to the parts, also transmits and modifies the available mechanical energy into some kind of desired work. It is neither a source of energy nor a producer of work but helps in proper utilization of the same. The motive power has to be derived from external sources. A slider - crank mechanism converts the reciprocating motion of a slider into rotary motion of the crank or vice versa. Figure-1 (Available) force on the piston → slider crank + valve mechanism → Torque of the crank shaft (desired). Examples of slider crank mechanism → Automobile Engine, reciprocating pumps, reciprocating compressor, and steam engines. Examples of mechanisms: type writer, clocks, watches, spring toys. Rigid body: A body is said to be rigid if under the action of forces, it does not suffer any distortion.

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Kinematic pairs according to nature of mechanical constraint (a) Closed pair : When the elements of a pair are held together mechanically, it is known as a closed pair. The contact between the two can be broken only by destruction of at least one of the member. (b) Unclosed pair : When two links of a pair are in contact either due to force of gravity or some spring action, they constitute an unclosed pair. Kinematic pairs according to nature of relative motion: (a) Sliding pair: If two links have a sliding motion relative to each other, they form a sliding pair. (b) Turning pair: When one link has a turning or revolving motion relative to the other, they constitute a turning or revolving pair. (c) Rolling Pair: When the links of a pair have a rolling motion relative to each other, they form a rolling pair. (d) Screw pair: If two mating links have a turning as well as sliding motion between them, they form a screw pair. Ex – lead screw and nut. (e) Spherical pair: When one link in the form of a sphere turns inside a fixed link, it is a spherical pair. Ex – ball and socket joint. Degrees of freedom: An unconstrained rigid body moving in space can describe the following independent motions. 1. Translational motion along any three mutually perpendicular axes x, y, z and 2. Rotational motions about these axes. Thus, a rigid body possesses six degrees of freedom. Figure - 3