ASA 127th Meeting M.I.T. 1994 June 6-10

5pSA1. Effect of different boundary conditions in the finite element modeling of acoustic field problems involving infinite domains---An application to smart structures.

Vasundara V. Varadan

Jaehwan Kim

Vijay K. Varadan

Res. Ctr. for the Eng. of Elect. and Acoust. Mater., Dept. of Eng. Sci. and Mech., Penn State Univ., University Park, PA 16802

In the modeling of structural acoustic problems involving infinite domains, finite element modeling is often used in regions involving complex geometry, material anisotropy, coupled fields, etc. These same problems often involve coupling of the structure with an infinite acoustic fluid. Several methods have been proposed involving infinite elements, Dtn boundary conditions, matching the FEM representation with analytical representations in the infinite domain, to name a few. In modeling the response of embedded sensors and actuators in a structure subject to fluid loading, we have found it convenient to match plane wave solutions in the acoustic fluid with the FEM representation. The matching can be done with and without slope constraints and the matching can also be done using the so-called Dtn (Dirichlet to Neumann) boundary condition that results from the radiation conditions in the infinite domain. A parametric study of convergence and accuracy of numerical results using each of these methods will be presented.