C. L. Yapura V. K. Kinra
Ctr. for Mech. of Composites, Dept. of Aerosp. Eng., Texas A&M Univ., College Station, TX 77843-3141
Consider a fluid--solid bilayer of infinite extent with the x[sub 3] axis perpendicular to the bilayer and the material axes coinciding with the x[sub 1], x[sub 2], and x[sub 3] axes. The fluid is assumed to be elastic (and isotropic) while the solid is assumed to be elastic and orthotropic (i.e., with nine independent elastic constants). Consider a plane wave propagating in the x[sub 1] direction with the particle motion confined to the x[sub 1]-x[sub 3] plane and plane strain conditions in the x[sub 2] direction. There are six boundary conditions: zero normal and shear stresses at the traction-free boundaries, zero shear stress and continuity of normal displacements, and normal stresses at the interface. The dispersion equation is obtained by setting the determinant of the resulting six-by-six matrix to zero. Numerical results in the form of phase velocity, group velocity, and mode shapes are presented for the case of a water/graphite-epoxy bilayer. Several interesting features are observed and discussed. The physics underlying these phenomena has been explored by studying the mode shapes at (and in the vicinity of) the frequencies of interest. [Work supported by Texas Advanced Technology Program.]