Classification of vibrations

Abstract

Vibrations are characterized by time-varying, more or less periodical processes. The sinusoidal vibration of an electric oscillator, the periodic swinging of a simple pendulum, or the random motion of a building subjected to gusts of wind are typical examples of vibrating systems. Processes of limited duration are also included in the notion of vibrations. Due to unavoidable energy dissipation, free vibrations will decay in practice and a strongly damped vibrating system will display short-term vibrations under excitation by impulse forces. These few examples show the need for putting some order in the variety of vibration phenomena, i.e., a need for a classification within the large class of vibrating systems. Such a classification will also be useful for a clear definition of the contents of this book.