Modeling of granular materials - a numerical model using lattices

In this paper, a numerical model is presented in which the particles in a granular assembly are modeled as lattices. In a two dimensional simulation, nodes are introduced at particle contacts and are linked by bar elements. A granular assembly is then transformed into a statically indeterminate truss and is analyzed using standard techniques in structural mechanics. The areas of bars are derived by computing the displacements of an elastic disk under contact forces and then the bar areas that will give equivalent displacements in the direction of the bars are determined. The lattice type model incorporates bonding, debonding, sliding and rotation of particles. The lattice type model has been applied to loose and dense packing of disks. The two packings were subjected to simple shear deformation after an initial vertical load was applied. The results from the lattice type model agree with the results from numerical tests using the discrete element method and with results of photoelastic experiments.