### ASA 124th Meeting New Orleans 1992 October

## 3aSA11. An orthogonal modes approach to fluid-loaded elastic structures
with arbitrary forcing functions.

**Jeffery A. Giordano
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*Graduate Prog. in Acoust., Penn State Univ., 157 Hammond Bldg., University
Park, PA 16802
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**Gary Koopmann
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*Penn State Univ., University Park, PA 16802
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A numerical scheme is presented wherein the structural equations for an
elastic structure are coupled to the acoustic radiation equations and recast in
canonical form. The acoustic impedance matrix, which may be found via boundary
element methods or by the superposition method, is expanded in a power series
on angular frequency prior to coupling it with the structural matrices. The
resulting system of equations is then decomposed to find an orthogonal basis
set which uncouples the original equations. Once the basis set has been
determined, the structural response and acoustic radiation spectra may be
easily reconstructed for any arbitrary forcing function on the structure.
Results will be given for two water-loaded examples, a finite plate in an
infinite rigid baffle and a spherical shell.