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Comparison of Acoustic and Elastic Wave Scattering From Elliptical Shells.
NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON CT NEW LONDON LAB
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An acoustic scattering formulation has been derived from a modification of the extended boundary integral method developed for elastic wave scattering from infinite cylindrical shells of arbitrary shape. The boundary condition of no tangential component of surface traction at the fluid-shell interface allows a simplification of the thin shell equations assumed to describe the motion of the scatterer. Expansion of the normal and tangential displacements of the shell into Fourier series which are a function of arc length reduces the shell equations to algebraic form. For this presentation the geometry is specialized to elliptical shells. Results are presented for shells of different materials and eccentricities. Comparisons are made between acoustic scattering and elastic p-p wave scattering. At low frequencies, modal resonances dominate the response of the shell in fluid. In an elastic medium, the modal response at the shell is reduced. At higher frequencies, creeping waves are generated for particular angles of incident.
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