ABSTRACT

Many noise sources commonly encountered in practice are associated with vibrating surfaces, and with the exception of aerodynamic noise sources, the control of vibration is an important part of any noise-control program. Vibration is oscillatory motion of a body or surface about a mean position and occurs to some degree in all industrial machinery. It may be characterized in terms of acceleration, velocity, displacement, surface stress or surface strain amplitude, and associated frequency. On a particular structure, the vibration and relative phase will usually vary with location. Although high levels of vibration are sometimes useful (for example, vibrating conveyors and sieves), vibration is generally undesirable, as it often results in excessive noise, mechanical wear, structural fatigue and possible failure.