INTERACTION OF ACOUSTIC BEAMS WITH FLUID-LOADED ELASTIC STRUCTURES

This article describes experimental and theoretical results of acoustic beam reflection from curved and planar solid media subject to fluid loading, with emphasis on parametric studies of wave phenomena ascribable to curved and planar fluid-solid interfaces. Measurements on aluminum and stainless steel, in three geometries and two sizes, over many values of incident angle and angular or linear coordinate, have been performed in the extensive experimental program. Simultaneously, theoretical modeling of the acoustic beam-structure interaction has been carried out via a complex source point algorithm that accommodates wave-solid interactions for arbitrarily collimated acoustic sheet beams. The resulting scattering problem is solved in terms of rigorous spectral integrals that are approximated by high-frequency uniform asymptotics. The expressions obtained in this manner for the reflected field contain the interacting specularly reflected beam and leaky wave contributions, which establish the physical basis of the observed phenomena. Essentially all data have been compared to predictions of the model, with very good agreement found in most cases between model calculations and experimental data. Many aspects of the observed phenomena should be useful for the nondestructive evaluation of curved structures.