AN ELLIPSE-BASED DISCRETE ELEMENT MODEL FOR GRANULAR-MATERIALS

The discrete element method (DEM) models granular materials numerically as a collection of particles rather than as a continuum. Difficulties can arise when using the more common circular and polygonal shapes for modelling real granular materials. In particular, use of discs and spheres leads to typically low aggregate internal friction angles compared with real materials. This paper presents the detailed formulations for using the ellipse shape in discrete element modelling. Robust algorithms for computing ellipse-ellipse and ellipse-wall intersections are presented. Also shown are equations to assist in parameter selection and evaluation of macroscopic stresses and strains from the contact data. An initial validation test suite on rods of varying particle aspect ratio are presented. These results indicate that the ellipse-based DEM results in mechanical behaviour that is similar, both qualitatively and quantitavely, to the behaviour of real soils.