Author(s): Rachel A. Batto; Erland M. Schulson
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Abstract: The behavior of S2 ice under compressive loading changes from ductile to brittle as the strain rate is increased. One possible mechanism for the transition (Schulson, 1990) is the suppression of crack tip deformation. Specifically, it is proposed that rate-dependent deformation at the tips of wing cracks (ie., inclined cracks with extensions along the loading direction) is suppressed once the strain rate exceeds the transition value, and that wing crack growth is thus made possible. Photographic evidence is presented of wing cracks and their behavior in freshwater columnar ice. When compressed uniaxially across the columns at 10C over a range of strain rates bridging the transition, wing cracks were found at all rates. At the higher strain rates (greater than 3 x 10-5 s-1) they propagated, forming axial splits along the loading direction. Correspondingly the ice was brittle. At the lower rates where the ice was ductile, wing crack propagation was not observed even though short wings had formed. The transition strain rate and failure stress are compared with the model.
Year: 1992