Scattering of sound from concentric cylindrical shells

Scattered sound field from three concentric shells ensonified by a plane wave is treated. Formulation of the problem is carried out using impedance expressions for the shells and the acoustic media interior and exterior to the shells. Results of exact equations of elasticity have been used to obtain the shell impedances, making the results applicable to arbitrary thicknesses. The results show that in a target made up of multiple shells and layers, the first elastic continuum that the incoming waves interact, which most closely resembles an impenetrable target dominates scattering. For example, a very thick shell or a very light-density fluid layer effectively insulates scattering from the layers or shells in its interior. When locally resistive compliant coatings are placed on the surfaces of the shell, they alter the scattering response. A very compliant layer on the exterior of the target changes it to a pressure-release type of boundary. © 1991 Acoustical Society of America.