2. Introduction

Model CJS is an elasto-plastic behavior law adapted to the modeling of granular materials. It was developed at École Centrale de Lyon ([bib1], [bib2], [bib3]).

Version CJS implemented in Code_Aster is a hierarchical model with several levels of complexity. In its most complete expression, the model has two load surfaces: one is activated by isotropic stresses, the other by deviatory stresses. The first undergoes isotropic work hardening and the second a mixed work hardening (isotropic and kinematic). The elastic law is of the nonlinear hypoelastic type.