Stress, stress-asymmetry and contact moments in granular matter

Abstract

The physical nature of contact moments within granular assemblies is reviewed and a new approach is developed for the homogenisation of stress within these materials. This approach revolves around capturing the effects of contact moments through the concept of contact eccentricity. By this method it is possible to calculate an expression for bulk stress that is both symmetric for material in equilibrium and fully consistent with the usual definition of bulk stress as an ensemble average of material stress over a representative volume element. The technique is demonstrated in a simple two dimensional example, as well as a larger scale discrete element modelling simulation of a steady state direct shear experiment.