THEORETICAL AND NUMERICAL MODELING OF GRANULAR LIQUID-SATURATED ELASTOPLASTIC POROUS-MEDIA

Liquid-saturated elasto-plastic porous media can be described within t he well-founded framework of the Theory of Porous Media (TPM) [1-3]. I n the present article, the TPM formulation of the skeleton material is extended by micropolar degrees of freedom in the sense of the Cossera t brothers [4, 5]. Proceeding from two basic assumptions, material inc ompressibility of both constituents (skeleton material and pore-liquid ) and geometrically linear solid deformations, the non-symmetric effec tive skeleton stress and the couple stress tensor are determined by li near elasticity laws. In the framework of the ideal plasticity concept of porous materials, the plastic yield limit is governed by a smooth and closed single-surface yield function together with non-associated flow rules for both the plastic strain rate and the plastic rate of cu rvature tenser. Fluid viscosity is taken into account by the drag forc e. The inclusion of micropolar degrees of freedom, in contrast to the usual continuum mechanical approach to the TPM, allows, on the one han d, for the determination of the local average grain rotations and, on the other hand, additionally yields a regularization effect on the sol ution of the strongly coupled system of governing equations when shear banding occurs.