ABSTRACT
The distinctive features of the propagation of elastic waves in isotropic solids are, however, manifested primarily at the boundaries as different types of surface waves, mixed deformations, transformation of waves with reflection from boundaries. Unlike liquids and gases, which in practice exhibit only bulk elasticity, solids also exhibit shear elasticity. Both longitudinal and shear waves, which propagate at different velocities and are therefore reflected and refracted at different angles, arise in both media. Thus, at the boundary between solids, waves of one type are transformed into waves of another type, as a result of which, in general, two reflected and two refracted waves propagating in different directions arise at the boundary. Thus a longitudinal ultrasonic wave incident at an arbitrary angle from a liquid on the boundary with a solid decomposes into a longitudinal and a shear wave. The Rayleigh waves studied can propagate along a free surface of a solid.
