Hysteresis and dichotomous mechanics in cyclic crushing failure of confined freshwater columnar ice

Cyclic crushing experiments with a haversine velocity waveform were performed on passively confined, freshwater columnar ice specimens for variety of velocities and frequencies. The aim the was to study deformation failure behavior in when loaded at predefined displacement pattern closely resembling frequency lock-in regime ice-induced vibrations. focus development load grain specimen scales during each cycle. To this end, observed crossed-polarized light highlight microstructure in-situ cyclic crushing. It shown that there are dichotomous mechanical behaviors damaged confined single cycle: brittle high non-brittle low velocity. At velocity, fracture interrupted stress relaxation occurred until began increasing accompanied by stress-optic effects ice. found peak-velocity hysteresis developed peak loads following temporarily higher than behavior. temporary enhancement tended increase duration relaxation, i.e. decreasing frequency. Negligible highest mean tested 2 Hz 10 mm s?1, respectively. For tests minimum 1 no measurement. Preliminary results from deviating showed decreases, but does not decrease. is speculated anelastic could account rapid unclear what causes hysteresis, although it dynamic strain aging might play role. change demonstrates mechanism which develops rapidly therefore incite vibrations vertically-sided structures.