A slightly inhomogeneous surface wave in a two-layered medium involving an isotropic layer and weakly anisotropic half-space

Abstract

The problem of transformation of a volume SH wave propagating along an isotropic elastic half-space with a free boundary into a new wave as a result of the half-space change (through small variations of elastic moduli) into a two-layered medium involving an isotropic layer and a weakly anisotropic half-space with cubic symmetry is investigated. The isotropic elastic moduli of a layer’s material therewith are equal to isotropic parts of the anisotropic moduli of a half-space material. Two types of the two-layered medium are considered: the medium wherein the shear wave velocity in the half-space is the same as the layer (‘‘neutral’’ layer) and the medium wherein the shear wave velocity in the layer is smaller than the shear wave velocity in the half-space (‘‘decelerating’’ layer). The new waves that evolve from these cases are demonstrated to be slightly inhomogeneous quasitransverse surface waves of the SH type, because among the three displacement components of these waves the transverse one, which is parallel to the interface of two media, predominates. As an example, two-layered media are considered where materials for the layer and half-space are isotropic and anisotropic tungsten, respectively.