Mechanical vibrations - Essay Example

Electromechanical devices also create mechanical vibrations. Fig 1 shows different types of vibration that are common sources of vibrations. The for examples of the daily life vibrations. Elementary Parts of Vibrating system The vibration of the body corresponds to the release and storing of the energy. The body stores the potential energy. There should be a mean to store the kinetic energy. In spring mechanism, spring stores the potential energy and mass is the medium that converts the potential energy is the spring to kinetic energy.

In the similar case of pendulum, the length of the string determines the capacity of the system to store the potential energy and the mass acts to convert the potential energy into kinetic energy (Den Hartog, 1956). The major part of any vibrating body is the damping in the vibration that gradually tends to loss the energy of the vibrating body. In some cases where vibrations are undesired damping constants are high by absorbing the vibrations or by creating negative oscillations. The major types of forces that are acting on a vibrating system are disturbing forces, restoring forces, inertia force, damping force.

Disturbing forces are forces which act to energize the system to make vibration in the system. Inertia force is the force that makes the vibrating body to remain in motion. Damping force is the force that tends to stop the motion of the body by damping the energy of the vibrating system (Den Hartog, 1956). Fig 2 depicts the mass attached to the spring showing the vibratory motion. F depicts the force, m is the mass, L is the length of the spring. Degree of freedom refers to the coordinates available for the motion of the vibrating body.

The coordinates to evaluate the instantaneous position of the system at its each part is a degree of freedom of that system. A finite degree of freedom corresponds to a discrete or lumped parameter system; while an infinite degree of freedom corresponds to a continuous or distributed system. Classify various types of vibration in mechanical systems. Types of Vibration in Mechanical System In any mechanical system, the vibrations are typified according to their classification. The classifications of different vibration are as follows.

Classification of Vibration: Vibrations in a system or within a system can be classified as • Free and forced • Damped and undamped • Linear and nonlinear • Deterministic and Random Free vibration Consider a vibrating system that is only once disturbed by exerting an external force and then the system vibrates with any further external force or disturbance. The vibration of such system is free vibration. If the mass attached to the spring is once stretched and then the eternal force is removed, the spring mechanism shows vibration on its own, this type vibration is called free vibration.

Forced Vibration: Forced vibrations refer to the type of vibrations that are due to the constant disturbance or repeating external force. Car engines, generators, and other constantly moving mechanical devices produce forced vibrations (Seto, 1964). Damped Vibration Damped vibrations are due to the damping factor that makes the system to gradually loss the energy and slow down the vibration of the system. Consider the mass attached to the spring, if it is once stretched and then the external force is removed; the vibration of the mass attached to the spring will gradually slow down due to the presence of damping force (Francis, Morse &