Vibrations by Balakumar Balachandran, Edward B. Magrab




INTRODUCTION

Vibrations occur in many aspects of our life. For example, in the human body,

there are low-frequency oscillations of the lungs and the heart, high-frequency

oscillations of the ear, oscillations of the larynx as one speaks, and oscillations

induced by rhythmical body motions such as walking, jumping, and dancing.

Many man-made systems also experience or produce vibrations. For example,

any unbalance in machines with rotating parts such as fans, ventilators,

centrifugal separators, washing machines, lathes, centrifugal pumps, rotary

presses, and turbines, can cause vibrations. For these machines, vibrations are

generally undesirable. Buildings and structures can experience vibrations due

to operating machinery; passing vehicular, air, and rail traffic; or natural

phenomena such as earthquakes and winds. Pedestrian bridges and floors in

buildings also experience vibrations due to human movement on them. In

structural systems, the fluctuating stresses due to vibrations can result in fatigue

failure. Vibrations are also undesirable when performing measurements

with precision instruments such as an electron microscope and when fabricating

microelectromechanical systems. In vehicle design, noise due to vibrating

panels must be reduced. Vibrations, which can be responsible for unpleasant

sounds called noise, are also responsible for the music that we hear.


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