Characteristic features of the velocity dispersion of surface acoustic waves in anisotropic coated solids

Basic patterns of the velocity versus wavenumber dispersion of the surface waves in solids coated by a relatively light or dense, "slow" or "fast" layer are discussed in the general case of an arbitrary anisotropy of substrate and coating materials. The onset of the subsonic wave branch, characterized by either a speeding or a slowing trend, is examined. Competitive tendencies, which pertain to the low-frequency dispersion in the case of dense "fast" layer, are revealed.