Andrew L. Fortt

Does the normal stress parallel to the sliding plane affect the friction of ice upon ice

Sliding experiments were performed at –108C on smooth surfaces of freshwater columnargrained S2 ice sliding against itself at a velocity of 8 10m s, with the purpose of examining whether normal stress parallel to the sliding plane affects frictional resistance. This component of the stress tensor was varied (0.20–1.83MPa) using a loading system operated under biaxial compression, by orienting the sliding plane at two different angles, 268 and 648, with respect to the principal loading direction. Under these conditions, no evidence was found to indicate that the normal stress in the direction of sliding affects the friction coefficient.

Do loading path and specimen thickness affect the brittle compressive failure of ice

Compressive experiments were performed on square (160 mm � 160 mm) prismatic speci- mens of columnar-grained, S2 freshwater ice, biaxially loaded across the columns at -108C. The work focused on brittle behavior, achieved by deforming the specimens at an applied strain rate of 4.5 � 1.2 � 10 -3 s -1 in the direction of shortening. The results show that the specimen thickness (25-150 mm) has no detectable effect on the terminal failure strength of the ice. Likewise, the strength of the ice when loaded under proportional loading, where the minor stress varies during the test, was similar to that when loaded under a constant minor stress, implying that terminal failure depends only on the stress state and not on the path taken.