The influence of the inter-particle sliding, rolling and torsion resistance on the skew-symmetric stress of sheared granular materials

Granular materials are made of discrete particles that interact with each other through their contacts (forces and torques). On the example of a particle simulation of a Cartesian (planar) split-bottom shear cell, we show the effect of microscopic resistance contact parameters between spherical particles on macroscopic continuum fields. Our results show that rolling friction has the strongest effect on the non-classical micropolar skew-symmetric stress. This skew-symmetric stress peaks in the same area as the shear band, and remains finite outside of it for vanishing shear rate. Its magnitude shows an increasing correlation with increasing shear band width. Torsion resistance has a similar, but smaller influence, whereas the correlation of sliding resistance only is almost negligible.