Dynamics of Machinery

1. What is meant by Dynamics of Machinery?
            Dynamics of Machinery is the branch of mechanics of machines which deals with the forces and their effects while acting upon the parts of machinery which are in motion. i.e. system changes with time.

2. Define force.
            It is an action in the form of push or pull exerted by one body on another body. Force produces or tends to produce motion.

3. State Newton’s First law of motion.
Every body continues in its state of rest or of its uniform motion in a straight line unless an external force acts on it.

4. State Newton’s Second law of motion.
The rate of change of momentum of the body is directly proportional to the force acting on it and takes place in the direction of force. This is used to measure a force quantitatively .i.e. F= m.a

5. State Newton’s Third law of motion.
            For every action there is equal and opposite reaction. It means that the force of action and reaction between two bodies are equal in magnitude but opposite in direction.

6. What is meant by applied force and write it types?
The external forces acting on a system of bodies from outside the system are called the applied forces .In other words, applied forces are the forces applied external to a body. Types:   1. Active force                        2. Reactive fore

7. What is meant by Constraint force?
            When two or more bodies are connected together to form a group or system, the pair of action and reaction forces between any two of the connected bodies are called Constraint forces. In other words, constraint forces are the forces existing internally within a body.

8. Define static force analysis.
It is a force analysis in which the inertia forces of the machine components are neglected.

9. Define static equilibrium.
A body is said to be in static equilibrium if it remains in its state of rest or of its uniform motion.

10. Define principle of superposition.
In liner systems, if a number of forces act on a member, the net effect is equal to the superposition of the effects of the individual forces taken one at a time.

11. What is the principle of virtual work?
It state that if a system is in equilibrium and undergoes an infinitesimal displacement from its equilibrium position without any lapse of time, the net work done is equal to zero

12. Mention the principles used in static force analysis.
            1. Principle of superposition
2. Principle of virtual work

13. What is dynamic force analysis?
It is defined as the analysis of various forces acting on the components of the machine or mechanism by taking inertia force due to accelerating parts into account.

14. Define D’ Alembert’s principle.
            It states that when a body is said to be in dynamic equilibrium, the vector sum of all external forces and inertia forces acting upon a system of rigid bodies is zero. The vector sum of all external moments and inertia torques acting upon a system of rigid bodies is also separately zero.

15. What do you mean by inertia force?
Inertia force is a property of matter by virtue of which a body resists any change in velocity.

16. What do you mean by inertia torque?
            Inertia torque is a property of matter by virtue of which a body resists any change in angular motion.

17. Define crank effort.
            Crank effort is the net effort applied at the crank pin perpendicular to crank, which gives the required turning moment on the crankshaft.

18. Define crank-pin effort.
            The component of force acting along the connecting rod perpendicular to the crank is known as crank-pin effort.

19. Define Piston effort.
            Piston effort is defined as the net or effective force applied on the piston, along the line of stroke. It is also known as effective driving force (or) net load on the gudgeon pin.

20. Explain the term maximum fluctuation of energy in flywheels.
            The difference between the maximum and minimum energies is known as maximum fluctuation of energy.

21. Define coefficient of fluctuation of energy.
            It is the ratio of maximum fluctuation of energy (ΔE) to the work done per cycle.

22. Define coefficient of fluctuation of speed.
            It is the ratio of maximum fluctuation of speed to the mean speed is called coefficient of fluctuation of speed (Cs)

23. Why flywheels are need in forging and pressing operations.
In both forging and pressing operations, flywheels are required to control the variations in speed during each cycle of an engine.

24. List out few machines in which flywheel are used.

1. Punching machine
2. Shearing machine
3. Crushing machine
4. Riveting machine

25. Define the term turning moment diagram.
            Turning moment diagram is the graphical representation of the turning moment or torque or crank effort for various positions of the crank.