On rheology and thermodynamics of irreversible processes

By generalizing the thermodynamical theory for elasticity and plasticity, developed by the author in a previous paper, a general formalism is obtained in which such phenomena as elasticity, plasticity (Maxwell bodies), viscoelasticity (Kelvin bodies), and viscous fluid flow are included. The rheological equations for Jeffreys bodies (viscoanelastic media without memory) are derived. It is seen that (also in isotropic media) a cross-effect may exist between viscoelasticity and anelasticity (plasticity). We restrict ourselves to small elastic and inelastic deformations.