POWER-LAW CREEP OF POWDER BONDED BY ISOLATED CONTACTS

The deformation of powder due to power-law creep near the interparticle contacts is modeled. It is assumed that the plastic dissipation is dominated by the rate of approach of neighboring particles and that the effect of tangential motion can be neglected. To characterize the creep law, the macroscopic strain rate in the powder aggregate is specified and the energy dissipated in power-law creep is computed. This work rate is used in a potential to determine the macroscopic creep parameters. The effective macroscopic shear and dilatational creep properties resulting from this model depend on the relative density of the powder. The creep rates are infinite at random close-packed density. A feature of the creep law is a high sensitivity to changes in deviatoric stress when the stress state is nearly hydrostatic and the creep exponent is high.