Mechanical Vibrations (WIND) (Paperback)

Introduction
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In your engineering dynamics course, you have come across the motions of a particle and of a rigid body. We have seen that motions of such systems are possible if disturbing forces or moments, whose resultant sum is not zero, act on them. We may, under such circumstances, call the motion of the system (that is a particle or a rigid body or may be their collections) as its response. Obviously, the response of the system in the form of its displacement (can be a linear or even angular), may change with respect to time.
If the time-varying response of any mechanical system against some disturbance is periodic (i.e. repeated response after regular time intervals) in nature, we say that the system is undergoing vibrational motion. This repeated response can be easily shown in a graph against time t. A typical plot can be as depicted in Figure 1.1. The characteristic of the periodicity of the response distinguishes the problem of vibration from any other dynamical situations of the concerned system that may occur with it. A system always vibrates with respect to any mean position. The mean position can be either the equilibrium position of the system or, the system can have vibrational motion with respect to the steady dynamical motion (e.g. oscillatory motion of a flywheel).
Sometimes, the word oscillation is also used to describe the vibrational motion but generally, it implies the periodic angular motion of a system (e.g. the oscillatory motion of a simple pendulum about which you have learnt in your physics lesson).