抄録
A thermodynamic derivation is given for the stress-strain representation of a medium having relaxation properties. This is done by means of the deviation ψij of the realxation tensor ψij appling Onsager's theorem to the thermodynamics of irreversible phenomena.
The main calculations in this study are as follows:
(1) In the general case of heating deformation, and in the plastic domatin, the kinetic equations are,
ψij+1/τψij=εij+γT
wheer εij is the strain tensor, ψij is the deviation tensor, T is the temperature, τ is the realxation time, and a dot represents the time differentiation.
(2) For quasi-stationary processes, the formula for the stress tensor is,
σik=Kεee-αKΔT+2η1(εik-1/3εeeδik)+η2(εee-γT)
where K is the bulk modulus and η is the coefficfient of viscosity.
(3) Mechanical stability posthulate is
(∂2F/∂ψi2)>0
