Cancellation techniques in underwater scattering of acoustic signals

Advanced materials made of a combination of viscoelastic coating and piezoelectric substances are fast emerging as important acoustics materials that can be used to reduce or eliminate scattered acoustic signals of submerged structures. In this paper, we considered the underlying principles that govern the acoustic performance of viscoelastic and piezoelectric materials. Analytical treatments such as the invariant embedding techniques, potential method, Floquet theory and asymptotics approximation, are employed to derive the mathematical model for predicting the acoustics performance of viscoelastic and piezoelectric materials. Numerical implementations in finite difference methods coupled with boundary integral formulation, and commercial finite elements code, such as ANSYS, are demonstrated for some practical configurations. Results for a few representative canonical examples of the problem, which include two-dimensional acoustic scattering from a fluid-loaded plate embedded with viscoelastic material or piezoelectric elements served as useful benchmarks for future works in this direction.