Abstract
A micromechanica model of the brittle compressive fracture of polycrystalline ice is presented in this paper. The model is appropriate for describing ice behavior in the ductile-to-brittle transition domain between −10 and −50°C. It is based on a statistical description of the ice microstructure, which contains crystals of random sizes and orientations and a random distribution of grain boundary crack precursors. The analysis takes into account microstructural stresses originating from the elastic anisotropy of the constituent crystals. A Coulombic friction model describes the frictional sliding of the precursors, which nucleate into cracks if a fracture criterion is satisfied. Crack-crack interactions, taking into account their arbitrary orientations, locations and sizes, are considered in the analysis, and brittle failure is predicted on the basis of a mode I fracture criterion. The interacting model is used to study the dependence of the failure stresses on the ice microstructure, temperature, rate of loading, mean grain size, and lateral confinement. Furthermore, microstructurally dependent expressions are developed for the elastic compliance of cracked ice, which is used to predict the deformation behavior prior to failure. The micromechanical predictions are also analyzed with the aim of providing insights for the formulation of phenomenological damage and failure theories.
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