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

4aSA4. Time-domain methods of analysis in structural acoustics.

P. R. Stepanishen

Dept. of Ocean Eng., Univ. of Rhode Island, Kingston, RI 02881

An overview of the use of time-domain methods to analyze the mechanical response of fluid loaded structures in vacuo and in fluid is presented. The response of a single degree of freedom mechanical oscillator will first be addressed and then used to build the solution to more complex plate and shell vibration problems using well established time-dependent eigenfunction or eigenvector expansions. In contrast to the in vacuo problems in which the modal coefficients are uncoupled convolution integrals, the coefficients for the fluid-loaded problems are shown to be described by a set of coupled convolution integral equations. The underlying physics that naturally leads to the coupled convolution integral equations will be discussed. Direct time-domain methods of evaluating the convolution integrals and solving the convolution integral equations will be presented and discussed. Finally, numerical results will be presented for both in-vacuo and in-fluid plate and shell problems to illustrate typical response characteristics.