Micro-mechanical Models for Polar Ice

This chapter is concerned with the behaviour of polar ice on geophysical time scales and its analysis by applying a micro-mechanical approach. Based on some assumptions regarding the anisotropic properties of an individual ice crystal and its microscopic deformation, frame-indifferent constitutive laws for creep response of the crystal are formulated. By applying homogenization methods, the microscopic laws are then used to derive the macroscopic constitutive relations for polycrystalline ice. These relations are employed to simulate the creep behaviour of ice in simple flow configurations in order to correlate parameters in the macroscopic flow laws with the observed anisotropic behaviour of polar ice. The chapter concludes with the analysis of the mechanism of dynamic (migration) recrystallization of polycrystalline ice. Three alternative dynamic recrystallization models are formulated, which are subsequently used in the simulations for simple flows to investigate the effect of th...