An analysis of the brittle to ductile transition in polycrystalline ice under tension

Abstract Concepts of dislocation micromechanics and of fracture mechanics have been used to derive a quantitative criterion for the brittle/ductile transition in polycrystalline ice under tension. The criterion is written in terms of a critical grain size dc, which is expressed as a function of both environmental parameters (temperature, strain rate) and material parameters (fracture toughness, lattice resistance to dislocation glide, grain boundary resistance to the propagation of slip). For d > d c the ice is considered to be brittle; for d c , it is ductile. While detailed experiments are needed to test the analysis, comparisons show reasonable agreement between theory and the limited data available.