9 Vibration Isolation for Noise Control

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One of the major sources of noise in mechanical equipment is the noise

produced by energy radiated from vibrating solid surfaces in the machine.

In addition, noise may be produced when vibratory motion or forces are

transmitted from the machine to its support structure, through connecting

piping, etc. Noise reduction may be achieved by isolating the vibrations of

the machine from the connected elements. For the case of noise generated by

a vibrating panel on the machine, noise reduction may be achieved by using

damping materials on the panel to dissipate the mechanical energy, instead

of radiating the energy into the surrounding air. In this chapter, we will

consider some of the techniques for vibration isolation for machinery and

examine some of the materials used in isolation of vibrations from equipment.

There are at least two types of vibration isolation problems that the

engineer may be called upon to solve: (a) situations in which one seeks to

reduce forces transmitted from the machine to the support structure and (b)

situations in which one seeks to reduce the transmission of motion of the

support to the machine. Some examples of the first case include reciprocating

engines, fans, and gas turbines. An example of the second case is the

mounting of electrical equipment in an aircraft or automobile such that

motion of the vehicle is not ‘‘fed into’’ the equipment.

Copyright © 2003 Marcel Dekker, Inc.

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