ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

2aSA11. Acoustic and flexural wave scattering from a three member junction.

Douglas A. Rebinsky

Andrew N. Norris

Dept. of Mech. and Aerospace Eng., Rutgers Univ., Piscataway, NJ 08855-0909

A three member junction is formed by a pair of semi-infinite plates in contact with fluid on one side and a mechanical structure on the other. The latter is described by an impedance matrix and the plates are modeled by the classical theory of flexure. The scattering problem for oblique incidence is solved using the impedance matrix for the plate junction without the attachment. This is accomplished using the Wiener--Hopf technique to solve the dual integral equations for the unknown pressure on the plates. Explicit formulae are obtained for the pressure transform, and corresponding explicit and relatively simple expressions are given for the various diffraction coefficients associated with the fluid/structure interaction. Numerical results for the redistribution of energy from flexural to flexural plus acoustic at a thickness discontinuity will be discussed in detail with respect to frequency and angle of incidence including the effect of various critical angles. It is verified that the general solution reduces to that for a pair of plates with clamped and welded junction conditions as limiting cases when the frame impedance is zero and infinite. [Work supported by ONR.]