Yuriy A. Rossikhin
Marina V. Shitikova
Dept. of Theor. Mech., Voronezh State Acad. of Construction and Architecture, ul. Kirova 3-75, Voronezh 394018, Russia
The problem on transformation of a volume SH wave propagating along an isotropic elastic space into a Stoneley wave in the consequence of the conversion of this space into a three-layered medium by small variations in material elastic moduli in a portion of the space is considered. The three-layered medium of two types has been investigated: A weakly anisotropic layer of cubic symmetry between two isotropic half-spaces and an isotropic layer between two slightly anisotropic half-spaces of cubic symmetry. In doing so, the elastic moduli of an isotropic material and isotropic parts of the moduli of a weakly anisotropic material are the same. Small anisotropic additions to the isotropic elastic moduli are entered by various means, so that velocities of SH waves in the slightly anisotropic materials with cubic symmetry obtained in such a way may be smaller, bigger, or equal to the velocity of SH waves in the corresponding isotropic material. It is shown that in those cases when the Stoneley wave exists, it refers to a weakly inhomogeneous quasitransverse wave of SH type, because among three displacement components weakly decaying with depth, the transverse one, which is parallel to the interface of three mediums, predominates.