Two Micromechanical Models in Acoustoelasticity: a Comparative Study

Herein we derive, under the micromechanical model we propose earlier (C. a complete set of for-mulae for the twelve material constants in the acoustoelastic constitutive equation for orthorhombic aggregates of cubic crystallites. We present also a second model and compare its predictions on the material constants with those of the rst model. Both these models lead to constitutive equations which are indiierent to rotation of reference placement. This allows us to appeal to a new representation theorem greatly facilitates our derivation of the formulae for the material constants. The second model introduced in this paper is intimately related to some previous averaging theories in the literature. We explain why and in what sense our second model could be taken as a generalization of its predecessors.