### ASA 125th Meeting Ottawa 1993 May

## 1pPA13. Transient sound radiation from impulsively accelerated bodies.

**Sean F. Wu
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*Dept. of Mech. Eng., Wayne State Univ., Detroit, MI 48202
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This paper presents an integral formulation derived from the Kirchhoff
integral theorem for predicting transient sound radiation from an impulsively
accelerated body. The acoustic pressure is determined in an explicit form in
the frequency domain, and subsequently converted to the time domain through
Fourier transformations. This integral formulation can be extended to cases in
which the body is subject to an arbitrarily time-dependent excitation. The
transient acoustic pressure is shown to be expressible as a convolution
integral of the impulse response function to the time history of the surface
velocity of the body. Since there is no relationship between the integral
formulations for the exterior and interior regions, solutions for the radiated
acoustic pressure in the exterior region are unique, even at frequencies
corresponding to the eigenfrequencies of the related interior boundary value
problem. Analytical results based on this integral formulation agree perfectly
with those obtained using other methods for transient sound radiation from an
explosively expanding sphere, impulsively accelerated rigid sphere, impulsively
accelerated baffled and unbaffled circular disks. [Work supported by ONR.]