A mesoscopic approach for modelling texture evolution of polar ice including recrystallization phenomena

Abstract

A material model for the simulation of anisotropic behaviour due to texture development in polar ice is presented. Emphasis is laid on the strain-induced texture development and its relaxation due to rotation recrystallization and grain boundary migration in the low-velocity regime. The model is based on two scales (mesoscopic approach). Kinematics, balance equations and constitutive assumptions are defined with respect to the grain level (mesoscale). Slip-system behaviour is assumed to be Newtonian. Recrystallization and grain boundary migration are taken into account via a diffusion-type evolution of the crystallites orientation. Due to the inextensibility of the ice crystallites along their c axes, the Sachs-Reuss assumption is adopted. Volume averaging yields associated macroscopic relations, where the internal structure is represented by a second-order structure tensor. The proposed approach is illustrated by applying it to initially isotropic material under homogeneous deformation, giving results qualitatively in agreement with experimental evidence. Finally, it is shown that the proposed model is, under some simplifying conditions, directly related to phenomenological internal variable models (e.g. Morland and Staroszczyk. 1998). © International Glaciological Society.