Contact Tensor in Constitutive Model for Granular Materials

The roles of the contact tensor in the constitutive model for granular materials are considered. After deriving the micromechanically based contact tensor and the modified stress tensor, we give possible physical meanings of them. The constitutive model with these tensors and their rates can account for more features of deformation of granular materials. The anisotropic hardening feature and the non-coaxiality between the rate of deformation and the stress tensors are given special attention in this paper.