ABSTRACT
A numerical model in the Cosserat continuum for strain localization phenomena in granular materials was developed by the authors. The mathematical formulations used in the present numerical model are equipped with evolution equations for the length scales through micropolar theory. The evolution equations of the internal length scales describe any possible change in the contact surface between the particles, damage to the particles if it exists and/or any change in the local void ratio within the domain. The solution for the shear bands thickness shows more accurate correlation with the experimental results and less dependency on the mesh size when such evolution equations are used.