A comparative study of micromorphic gradient‐extensions for anisotropic damage at finite strains

Abstract Modern inelastic material model formulations rely on the use of tensor‐valued internal variables. When inelastic phenomena include softening, simulations of the former are prone to localization. Thus, an accurate regularization of the tensor‐valued internal variables is essential to obtain physically correct results. Here, we focus on the regularization of anisotropic damage at finite strains. Thus, a flexible anisotropic damage model with isotropic, kinematic, and distortional hardening is equipped with three gradient‐extensions using a full and two reduced regularizations of the damage tensor. Theoretical and numerical comparisons of the three gradient‐extensions yield excellent agreement between the full and the reduced regularization based on a volumetric‐deviatoric regularization using only two nonlocal degrees of freedom.