ABSTRACT
ABSTRACT: Granular materials are made of interacting grains. The behavior of these materials is generally difficult to model, due essentially to the complex internal structure whose evolution is not easy to quantify. The goal of this paper is to clarify the different kinds of internal variables which can be used to describe the internal state of a granular material. These variables allow the local compactness, anisotropy and distribution of contact forces to be described. The evolution of these variables will be illustrated from numerical simulations using the distinct element method. The consequences on phenomelogical modeling will be drawn from this local analysis.
