### ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

## 5aSA3. Radiation sensitivity of baffled plates to structural perturbation.

**Steven R. Hahn
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Aldo A. Ferri
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*Mech. Eng. Dept., Georgia Inst. of Technol., MS 0405, Atlanta, GA 30332
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The analysis of acoustic radiation and scattering from submerged elastic
structures is an important and challenging problem. Often, numerical solutions
are hampered by the fact that the acoustic pressure field can be very sensitive
to structural detail. In this presentation, a baffled plate submerged in a
semi-infinite acoustic medium is used study this sensitive. A finite element
description of the structure and a boundary element description of the fluid
are used to model the plate-fluid-baffle arrangement. The sensitivity
information is obtained by applying perturbation techniques to the matrix
equations that arise, yielding exact derivatives of the chosen field variable.
Several types of local structural perturbations (point masses, springs,
dampers, and ribs) as well as global perturbations (Young's modulus, density,
damping) are considered. The nature of the structural sensitivity is examined
and some investigation is made into what types of structural features have the
greatest impact on radiation and scattering. Finally, the use of the
sensitivity information for engineering and design is discussed.