On the theory of the elastic wave propagation in a crystal coated with a solid layer II. Surface and leaky waves near a line of exceptional bulk waves

摘要

The existence of exceptional bulk, quasi-bulk-surface and pseudo-surface waves in a crystal of arbitrary anisotropy coated with a solid layer of arbitrary anisotropy is considered. One-component exceptional bulk waves that exist on the mechanically free surface are shown to disappear on the plated surface. They give rise to quasi-bulk-surface and pseudo-surface waves. The connection between the appearance of quasi-bulk subsonic surface waves and the existence of subsonic ordinary (Rayleigh) surface waves is investigated. In the plated crystal, instead of one-component exceptional waves, there arise three-component exceptional waves which involve the limiting bulk wave and two inhomogeneous modes. It is shown that the presence of an overlay in a general manner provides the existence of high-velocity (supersonic) pure surface waves near the intermediate transonic state and the existence of leaky waves near the highest transonic state. [References: 19]