On Plastic Strain in Porous Materials

Abstract

The formulation of continuum theories for inelastic response usually involves the definition of plastic strains or plastic strain increments. For solid materials, these are usually defined in terms of the residual deformation resulting from a loading-unloading stress cycle. For porous materials, the residual deformation may involve both irreversible and reversible deformation mechanisms in the solid matrix. We treat the special case of hydrostatic response of dry or fluid-saturated isotropic porous materials and we show that a particular definition of the plastic volume strain increment isolates the irreversible deformation mechanism, thereby making it perhaps the most useful definition for theoretical purposes.