A FLOW LAW FOR ANISOTROPIC ICE AND ITS APPLICATION TO ICE SHEETS

A new formulation of the flow law of polycrystalline ice was derived for an arbitrary c-axis orientation fabric pattern. The rate factor of the flow law is given by a geometrical factor that can be calculated with c-axis fabric data and stress condition. A theoretical calculation combining this flow law with a lattice rotation model by intracrystalline slip in the constituent grains predicts the development of characteristic fabric patterns observed in many laboratory experiments and in the field. According to this flow model of polycrystalline ice, if significant recrystallization does not occur uniaxial compression makes the ice body harder with increasing strain, whereas simple shear makes the ice body softer with strain. This may significantly affect ice sheet dynamics.