On the non-existence of subsonic boundary–polarized two-component free surface waves

Abstract

It is now known that one-component free surface waves (surface waves constructed from a single partial wave, i.e., a single inhomogeneous plane wave) can indeed exist in stable anisotropic linear elastic half-spaces. Such one-component waves are necessarily supersonic and are necessarily polarized in the free boundary of the half-space in which they exist (we denote the latter property as a "boundary-polarized" wave). Two-component free surface waves (which are constructed from a linear superposition of two partial waves, i.e., two inhomogeneous plane waves) are known to exist in both the subsonic and supersonic regimes in real anisotropic half-spaces. Here we prove that subsonic two-component surface waves cannot be "boundary-polarized."