### ASA 126th Meeting Denver 1993 October 4-8

## 4aPA10. Guided waves in a fluid--solid bilayered plate.

**C. L. Yapura
V. K. Kinra
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*Ctr. for Mech. of Composites, Dept. of Aerosp. Eng., Texas A&M Univ.,
College Station, TX 77843-3141
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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.]