Role of micro‐heterogeneities on fabric, stress, and elastic anisotropy in granular media

Abstract

We report the effect of micro‐scale contact heterogeneities on fabric, stress, and elastic anisotropy in granular media using granular dynamics simulation. Uniaxial compaction (with zero lateral strain) of initially isotropic frictional grain packs is the source of anisotropy in our computational experiments. We provide evidence of fabric anisotropy using second order fabric tensor. Further, the horizontal‐to‐axial stress ratio (K0) evolves non‐linearly and becomes constant with increasing uniaxial compaction. This stress ratio depends on the grain‐to‐grain friction, and possibly on “granular jamming”. We also show that the usual linear elasticity‐based expressions for estimating stress ratio are not good predictors for uniaxial compaction. We further estimate key elastic stiffness elements (C11, C33, C44, and C66). Analogous to our earlier results on isotropic compaction, we observe infinitesimal grain relaxation (without sliding) while computing elastic stiffness constants. We present functional forms of pressure dependent relaxation corrections for these constants.