Acoustic wave-based nondestructive control of the damaged layer and roughness parameters of the free surface of an anisotropic solid

Abstract

A method of nondestructive control of the damaged layer and roughness parameters of the surface of a hexagonal crystal and an isotropic solid with the use of Rayleigh and shear-polarized surface acoustic waves has been proposed. The surface under study borders on vacuum and can be a rough surface or an isotropic damaged surface layer. The problem is considered in the long-wavelength limit (as compared to the roughness amplitude or the thickness of the damaged layer, as well as to the characteristic radius of the surface heterogeneity). It has been shown that, in the long-wavelength limit, the dispersion of phase velocity and the damping length of shear-polarized waves can be found from the known values of the phase velocity dispersion and the damping length of the Rayleigh surface acoustic waves or vice versa. The problem for an isotropic damaged surface layer is treated in a special case where only the density fluctuates.