Modelling viscoplastic behavior of anisotropic polycrystalline ice with a self-consistent approach

A ViscoPlastic Self-Consistent (VPSC) model has been applied to polycrystalline ice in order to characterize the relation between the texture of the material and the instantaneous anisotropic mechanical behavior. We assume that ice crystals deform by basal, prismatic, and pyramidal slip. The resistance of these slip systems is determined by an inverse approach, based on the comparison between model results and results of several mechanical tests. The VPSC model well reproduces all experimental macroscopic behavior only if we introduce a small-but not negligible-amount of pyramidal slip, which is not observed experimentally. The introduction of this probably unrealistic slip system possibly corrects the errors linked to the assumptions of the model, that we discuss. We finally use the model to describe the behavior of some typical polar ices in relation to the symmetries of the texture. (C) 1997 Acta Metallurgica Inc.