Abstract
Hydrostatic pressure dependence in mechanical behavior of polymers is studied for the constitutive modeling with the effect of the first invariant of stress and a two-surface in stress space. A internal variable theory of rate-independent plasticity is presented incorporating isotropic hardening, Evolution equations for isotropic hardening variables are prescribed as a function of these internal variables and accumulated plastic strain. The model is compared with the experimental results in uniaxial tension and compression under high pressure by Spitzig and Richmond.
