Some remarks on the existence of one-component surface waves in elastic materials with symmetry

Abstract

It has recently been shown that there are physically realizable triclinic elastic media in which a free supersonic surface wave composed of a single inhomogeneous plane wave can propagate. The compatibility of such one-component surface waves with material symmetry is considered here, particular attention being paid to situations in which E1, the orthogonal complement of the wave normal, is a plane of symmetry. For these configurations the surface-wave speed is determined by a simple geometrical construction. A one-parameter family of transversely isotropic materials is specified each member of which admits a one-component surface wave when E1 is a zonal plane and the axis of symmetry is at 45° to the boundary normal. Families of transversely isotropic elastic materials supporting exceptional subsequent transonic states of types 4 and 2 are also defined.