Creep and Stress Relaxation in the Vicinity of a Micropore under the Conditions of Hydrostatic Loading and Unloading

A mathematical model of severe deformations when irreversible strains are represented by both plastic strains and nonlinear creep strains was developed. Equations were written out in the Eulerian form in order to describe the motions of the continuum in the rectangular Cartesian spatial coordinate system. When the stressed state in the material attains its loading surface, the deformation dissipative mechanism in the vicinity of the point under consideration changes, and plastic flow begins. The model allows to indicate rheological mechanisms for strengthening viscous elastoplastic materials under the conditions of significant exploitation loads of the loading-unloading type.