In the ninetys, I developped SDEC, a code using the Discrete Element Method. This code is based on a newtonian approach which uses rigid bodies. These elements are described in terms of their mass, volume and their interactions. The code herein uses spherical elements. Two elements may be considered as interacting while not touching. Any element within an interaction range of another element defined as a radius around this element will be interacting with the latter. The interactions are known as "soft sphere" interactions because the interaction forces are linked to the displacements of the elements which implies that the elements may penetrate or overlap one another.

Newton's second law of motion describes the motion of each element as the sum of all forces  applied on this element.The dynamic behavior of the system is solved numerically by a time  algorithm in which the velocities and the accelerations are constant at each time step. The system evolves and an explicit finite difference algorithm is used to reproduce this  evolution.

Until now,  this code has been used to treat geomechanical problemes in both quasi-static and dynamical applications.

Developing membranes in SDEC: coupling DEM with FEM

A specific module used to describe the membrane behavior of a geosynthetic sheet and its interaction with the soil has been developed by Pascal Villard and Bastien Lehello (LIRIGM). The coupling between the finite elements method and the discrete elements method combines the advantages of each method: using a continuous model defined by the macroscopic parameters to describe the fibrous structure of the geosynthetic sheet and its interaction with the soil, and using a discrete model to describe the mechanisms of rupture and collapse of the soil.

The new Discrete Element Sofware : YADE

This is the project of Olivier Galizzi's Phd thesis, with  an additional major contribution by  an other Phd student, Janek Kozicki. It is a free software with a GPL open source licence.  It includes the current version of SDEC.  At the 3S Lab, Bruno Chareyre, Wenjie Shiu, Luc Sholtes are using it.

You can down load this software at the following address :

http://yade.wikia.com/wiki/Yade