On the Mechanical Description of Mechanochemical Activation

Abstract

A thermodynamic derivation is given for the stress-strain representation of a medium having relaxation properties. This is done by means of the deviation ψ_ij of the realxation tensor ψ_ij 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,
ψ_ij+1/τψ_ij=ε_ij+γT
wheer ε_ij is the strain tensor, ψ_ij 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,
σ_ik=Kε_ee-αKΔT+2η₁(ε_ik-1/3ε_eeδ_ik)+η₂(ε_ee-γT)
where K is the bulk modulus and η is the coefficfient of viscosity.
(3) Mechanical stability posthulate is
(∂²F/∂ψ_i²)>0