Comparison of the macroscopic behavior of granular materials modeled by different constitutive equations on the microscale

In this paper a three- dimensional discrete element method ( DEM) is used to model cohesionless granular materials. Two different microscopic constitutive equations are used to resolve the contacts between single particles in the DEM: First, a simple penalty type contact law and second, a more sophisticated Hertzian type contact law. Numerical tests in form of DEM simulations of a cuboid particle sample under compression and shearing are performed using both microscopic constitutive equations. The microscopic results of the DEM in terms of inter- particle contact forces and particle trajectories are transferred to macroscopic results in terms of stresses and strains by a homogenization approach. The macroscopic results are presented and compared for the different microscopic constitutive equations. (C) 2007 Elsevier B. V. All rights reserved.