Abstract:
A new formulation that allows one to describe backscattered echoes from elastic shells near pressure release, rigid, and absorbing planer interfaces is presented. The proposed formulation is always consistent---in contrast to earlier formulations---even at low frequencies and large distances from the interface. It allows for the rapid reproduction of backscattered echoes over frequency ranges of practical interest. This novel approach is developed and is shown to be sufficiently general to allow for nonreflecting smooth surfaces. The method has been implemented and numerical results for both pulse and continuous wave signals scattering from various shells are carried out. The studies for various object materials, distances from the interface, and for the effect that the three type of interfaces have on the detected signals are presented. [Work supported by Naval Research Laboratory and Office of Naval Research.]