Viscoplastic regularization in strain localization simulation of multiphase porous materials

This work presents the implementation of a regularized constitutive model to avoid the mesh sensitivity problem in strain localization simulation of multiphase porous materials. For this purpose, a local viscoplastic constitutive model of Perzyna type [1] and its consistent viscoplastic tangent operator have been formulated and implemented in the finite element code Comes-geo developed at the University of Padua [2, 3, 5] based on the multiphase porous media model developed in [2] for quasi-static problems. For simplicity, the Drucker-Prager yield function with isotropic linear hardening/softening and non-associated plastic flow, has been incorporated in the viscoplastic algorithm. The regularizing effect of the viscoplastic model has been examined by the finite element simulation of a strain localization problem.