LABORATORY OBSERVATIONS OF ACOUSTIC EMISSIONS FROM ANTARCTIC FIRST-YEAR SEA ICE CORES UNDER CYCLIC LOADING

摘要

Microcracking in ice generates detectable acoustic emissions (AE), and the monitoring of AE during deformation provides valuable insight into the failure process. AE monitoring has been successfully applied in the field during in-situ cyclic loading and fracture experiments on sea ice, Those observations revealed AE concentrated at the tip of the starter crack, with a strong dependence on stress level and cyclic loading frequency. Moreover, it was clear that AE monitoring could provide valuable information on the size of the crack tip process zone. To better understand the relationship between loading conditions and the resulting AE activity observed in the field, acoustic activity was monitored in laboratory experiments on cores from the in-situ specimens. The present effort describes the laboratory methods and gives representative results regarding the influence on the acoustic activity of the direction (tension vs. compression) and magnitude of the applied stress, the cyclic loading frequency, and the number of load cycles.