Elastic strains on the free surface and the interface with the rigid body as structural elements of an inhomogeneous body.

The problem of elastic wave reflection on the free surface and on the interface with the rigid bidy is investigated in the approximation of geometrical acoustics. In both cases, the interface is considered as a structural element of an inhomogeneous body, which is characterized by dimensions and a set of physical-mechanical parameters. In the continuum mechanics the interface is generally viewed as an infinitely thin layer. Analytical expressions for the Fresnel coefficients allowing us to determine the strain components on the boundary are found at the normal incidence of P and SV waves. The dependences of the Fresnel coefficients and the strain amplitudes as functions of interface thickness and the elastic properties of contacting bodies are calculated and analyzed. [ABSTRACT FROM AUTHOR]