Aspects of energy propagation in highly anisotropic elastic solids

Abstract

Anomalies in the theory of wave propagation in constrained materials may be reconciled with the standard theory of wave propagation in unconstrained materials by relaxing the constraint slightly and then taking the limit as the constraint is obeyed exactly. In this paper the same method is employed in an attempt to reconcile anomalies in the propagation of energy in a constrained material with the known propagation propertics for unconstrained materials. On relaxing the constraint in a singly constrained material, it is found that the energetics associated with two of the three propagating waves tend to the appropriate known forms for the corresponding constrained material in the limit where the constraint holds exactly. The third wave has no counterpart in the constrained theory and it is conjectured that both the total energy density and the energy flux vector tend to zero as the constrained limit is approached. This conjecture is shown to be true for two simple boundary value problems involving incompressible, and inextensible, elastic half-spaces.