Numerical simulations related to polar effects in an infinite extended granular layer under shearing movement and constant vertical pressure are presented. The mechanical behavior of cohesionless granular soil is described within the framework of micro-polar (Cosserat) continuum and using an elasto-plastic constitutive relation. The influence of Cosserat rotations and couple stresses are taken into account using the mean grain size as characteristic length. Finite element method in Updated Lagrangian (UL) frame is used to consider large deformations during calculations. The numerical results demonstrate that for large shearing movement, the shear deformations within the granular layer are localized into a narrow zone. The FE-calculations indicate that the polar effects manifest by the appearance of noticeable grain rotations, high void ratios, pronounced volume changes within the localized shear zone.
The relaxed-polar mechanism of locally optimal Cosserat rotations for an idealized nanoindentation and comparison with 3D-EBSD experiments
