Comparisons of Backscattering from Cylindrical Shells Described by Thin Shell and Elasticity Theories.
NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON CT
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For Kh or O.65, where k is the fluid wavenumber and h is the shell wall thickness, scattering from infinite cylindrical shells at normal incidence can be described by a combination of specular reflection and the zeroth order symmetric Lamb waves that correspond to extensional and inextensional modes of shell theory. Love-Timoshenko thin shell theory is found to closely describe the resonance scattering behavior from these types of structural modes. At higher values of kh, scattering from the antisymmetric Lamb-type flexural modes is predicted by full elasticity theory. For materials in which the plate and modified shear waves speeds can be either greater or less than the wave speed in the backscattering predictions of fluid, the accuracy of Love-Timoshenko thin shell theory will be investigated near the excitation of the antisymmetric Lamb-type flexural waves by comparisons with full elasticity theory. Plate theories will be used to develop a physical explanation of the resulting differences.