Thermodynamic restrictions, free energies and Saint-Venants principle in the linear theory of viscoelastic materials with voids

This paper examines the thermodynamic restrictions imposed by the second law of thermodynamics upon the relaxation functions in the linear theory of viscoelastic materials with voids[ On this basis the existence of a maximal free energy is proved by means of a constructive method[ Further\ we use such a maximal free energy in order to establish a principle of Saint!Venant type in the dynamics of viscoelastic materials with voids[ A uniqueness theorem is proved for _nite and in_nite bodies and we note that it is free of any kind of a priori assumptions concerning the orders of growth of solutions at in_nity[