Acoustic and flexural wave scattering from a three-member junction

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. The excitation is either a straight crested flexural wave traveling on one of the fluid-loaded plates and obliquely incident on the line junction, or an acoustic plane-wave incident from any direction in the fluid. The general solution for this type of scattering problem is derived and illustrative numerical examples are given. The admittance matrix for the fluid-loaded plate junction without the attachment plays a central role in the solution. 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. The numerical results display two well-defined characteristic critical angles for transmission of structural energy and diffraction of acoustic pressure. © 1995 Acoustical Society of America.