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

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

Steven R. Hahn

Aldo A. Ferri

Mech. Eng. Dept., Georgia Inst. of Technol., MS 0405, Atlanta, GA 30332

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.