MEAN-FIELD INELASTIC BEHAVIOR OF RANDOM ARRAYS OF IDENTICAL SPHERES

We consider a random array of identical spheres that interact through noncentral contact forces. We assume that the displacement of a contac t relative to a center may be calculated from the average strain of th e aggregate. The normal component of the contact force is assumed to b e Hertzian and the tangential component is assumed to be linearly elas tic until frictional sliding occurs. We consider the response of the m aterial in triaxial compression. For monotone deformations, we calcula te the evolution of the contact distribution, the volume change, the s tress-strain response, the plastic string, and the strain hardening.