45.1 Introduction

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This chapter describes the basic concepts of the method of statistical energy analysis (SEA) and presents

its application to structures. The analysis and computation techniques for vibration response and

radiating sound in instruments and structures vary according to the characteristics of the physical

object and the frequency range of interest. Here, we analyze vibration and noise in relation to a rather

large-scale structure over a wide frequency band. Extensive computations are usually required, when,

for example, the finite element method (see Chapter 9) is used for the computations, with respect to a

given oscillation mode. In particular, when the computations must be performed in the high-frequency

range and when many modes are included in the frequency band, the level of computation becomes

considerable, generally resulting in reduced computational accuracy. To supplement the weak point of

the traditional approach, it is necessary to redistribute statistically the energy equally from all modes in

the analytical frequency band. This allows computed results to be compared with experimental results

for a structure across a wide frequency band. This is the SEA method [1]. Early in its development, the

objective of this analytical method was to predict the vibration response of artificial satellites and

rockets that receive sound excitation when the jet discharges, and to predict the response of vibration

stress in the boundary layer noise of an aircraft’s airframe. It also became a model that allows an

45-1

© 2005 by Taylor & Francis Group, LLC

exciting force to be statistically (randomly) diffused (distributed) over a wide frequency band. This

technique considers energy of excitation of a diffused (distributed) sound field and its variables

that represent the sound pressure, acceleration, and force. Thus, it can be applied to problems of

solid-borne sound in which vibration propagates through each element [2] and problems of air-borne

sound in which multiple barriers exist [3], even when more excitation points than one are present.

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