SENSITIVITY ANALYSIS OF COUPLED STRUCTURAL-ACOUSTIC PROBLEMS USING PERTURBATION TECHNIQUES

The analysis of acoustic radiation and scattering from submerged elast ic structures is an important and challenging problem. Often, numerica l solutions are hampered by the fact that the acoustic pressure field can be very sensitive to structural detail. In this paper, a procedure for obtaining the sensitivity of a structural-acoustic system to stru ctural perturbations is presented. The theoretical development assumes a finite element description of the structure and a boundary element description of the fluid. The analysis includes full coupling between the fluid and the structure, and can accommodate both internal and/or external fluid regions. The types of perturbations are limited to thos e that do not alter the geometry of the wetted surface, but are otherw ise completely general in nature. The technique is then applied to aco ustic scattering from a cylindrical shell. Two perturbations are consi dered: A change in the shell thickness and a change in the elastic mod ulus. The effect of these structural perturbations on the surface pres sure, surface normal velocity, and scattered pressure are examined for plane-wave scattering. (C) 1997 Acoustical Society of America.