Interaction of acoustic waves generated by coupled finite fluid-loaded plates.

摘要

In this dissertation the response of two coupled finite plates set in two alternative configurations is considered. The plates are simply supported on two edges, with arbitrary boundary conditions on the remaining two edges. The solutions obtained for the response of the plates include both the structural interaction at the common junction and the acoustic interaction due to the scattered pressure from each of the two plates.;The solution is based on a formulation developed in the wavenumber domain combined with the Mobility Power Flow method. Using this approach, different substructural elements coupled under different boundary conditions to form a complex global structure can be considered.;In obtaining the solution for the scattering from the fluid-loaded plates, a modal decomposition in the direction normal to the simply supported edge is used. A spatial Fourier-transform decomposition is used in the other direction. Due to the finiteness of the plate, eight unknowns parameters are obtained in the transformed result. The solution for these eight unknown parameters is obtained from the boundary conditions and the condition that the response must remain finite. Two analytical approaches are used to solve the final plate integral equation. The first approach consists of an approximation method which obtains a solution based on the solution of the corresponding infinite plate problem. The second approach is a more accurate solution based on the Projection Method for the solution of integral equations.;Both of the approaches used in the solution provide accurate predictions at high frequencies. At low frequencies especially for low structural damping or for heavy fluid loading, only the Projection Method gives reliable results.;The application of the method to coupled fluid-loaded plates indicates that the junction enhances the scattering properties. The acoustical interaction between the coupled plates increases the contribution to scattering from subsonic wavenumber components. In the absence of the interaction, only supersonic wavenumbers contribute to the scattering. Inclusion of acoustical interaction requires both supersonic and subsonic components. The significance of the contribution from the subsonic wavenumber components is dependent on the type of the fluid loading. (Abstract shortened by UMI.).