Author(s): David M. Cole
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Keywords: No Keywords
Abstract: This paper examines the response of ice specimens to reversed direct-stress loading. The variables include the cyclic loading, temperature and microstructure. The specimens were laboratory-prepared single crystal, granular and columnar-grained freshwater ice and columnar-grained saline ice. The microstructural variables include grain size, shape and, in the case of the S2 columnar ice, orientation. The experimental results give evidence of two distinct relaxation processes: one results from the glide of basal dislocations and the other from a grain boundary mechanism. The dislocation relaxation is shown to have an activation energy in agreement with that for basal dislocation glide, and the activation energy and relaxation time for the grain boundary process are in good agreement with results in the literature. The experimental observations are examined with regard to the influence of microstructure and temperature on the operation of the two relaxation processes.
Year: 1994