Shear localization in ice: Mechanical response and microstructural evolution of P-faulting

Abstract

Systematic experiments on laboratory-grown polycrystalline granular ice and columnar S2 ice loaded triaxially under a high degree of confinement at T=−10°C to T=−40°C at applied strain rates ε˙11=1×10-5s-1 to ε˙11=2×10-1s-1 show the mechanical response and microstructural evolution leading to terminal failure. Terminal failure is characterized by a sudden brittle-like drop in load, localized heating and the development of a narrow shear band, consisting of recrystallized grains, oriented on a plane of maximum shear. This mode of failure, termed plastic (P) faulting, is consistent with the idea of adiabatic heating leading to localized mechanical instability and shear deformation. The microstructural state of the material, including the development of dynamic recrystallization and any prior loading history, does not have a significant affect on the character of shear localization or the levels of deformation required to generate P-faulting.