Cavity growth and grain boundary sliding in polycrystalline solids

A basic method is presented for the estimate of the overall mechanical response of solids which contain periodically distributed defects (inhomogeneities, regions undergoing inelastic flow, voids, and inclusions). This method is then applied to estimate the shape and growth pattern of voids that are periodically distributed over the grain boundaries in a viscous matrix. The interaction effects are fully accounted for, and the results are compared with calculations for a single void in an infinitely extended viscous solid, by Budiansky, Hutchinson, and Slutsky. Then, for a polycrystalline solid that undergoes relaxation by grain boundary sliding, the relaxed moduli are obtained, again fully accounting for the interaction effects. Finally, the overall inelastic nonlinear response at elevated temperatures is discussed in terms of a model which considers nonlinear power law creep within the grains, and linear viscous flow in the grain boundaries.