DEFORMATION WAVES IN THERMOELASTIC MEDIA AND THE CONCEPT OF INTERNAL VARIABLES

Nonlinear thermoelastic continua with Fourier's type of heat conductio n illustrate complex systems composed of internal and reaction-diffusi on subsystems. An evolution equation is derived for the observable var iable (deformation) when temperature effects are viewed as internal pr ocesses. This approach, which pertains to the so-called instantaneous wave analysis, shows that thermal losses accompanying the deformation wave correspond to the low-frequency approximation.