The Effect of Stress Application Rate on the Creep Behavior of Polycrystalline Ice

Abstract

This work examines the effect of the rate of stress application on the creep behavior of polycrystalline ice. Stress rates from 10−3 to 1.84 MPa s−1 were used to achieve a creep stress of 3.6 MPa at test temperatures of −5° and −10°C. The treatment emphasizes the effect of stress application rate on primary creep behavior and the accompanying microfracturing activity. Acoustic emission measurements taken in all tests indicate the onset and rate peak of the microfracturing activity. The stress application rate has little effect on the minimum strain rate, the strain at which it occurs, or the characteristics of tertiary creep provided that the loading ramp ends prior to reaching the nominal failure strain of 1.0 percent. Primary creep behavior is significantly affected only at rates below about 10−2 MPa s−1 . Results indicate that when the loading ramp continues through the failure strain, no minimum strain rate occurs, but rather the strain rate increases monotonically throughout the entire test.