ABSTRACT
The state variables defining the thermoelastic solids considered are the strain and the temperature. Heat conductors and non conductors enjoy distinct, although parallel, dynamic properties which may be compared systematically. By contrast, the thermoelastic wave-speeds associated with a non conductor have been shown to be governed by the acoustic tensor of the underlying isentropic tensor moduli. The first order shear discontinuity is thus clearly isochoric. The second order hyperbolic partial differential equations, that govern the field equations of solids and saturated porous media, allow waves to travel forward and backward. The idea is to replace the field equations, in regions adjacent to the boundary, by partial differential equations that generate only waves that exit the body.
