OBSERVATIONS ON THE TIME-DEPENDENT FRACTURE OF ICE

The results of a recent ice indentation series, along with a 4-point beam bending series, are analysed in the present paper with regard to time-dependent fracture. The beam bending series used a a 4-point apparatus to test the effects of velocity on fracture toughness, and to study time delayed fracture at loading rates below the fracture strength of ice. The indentor series used different indentors (diameters ranging from 10 mm to 70 mm), and applied various velocities used to test the time-dependent fracturing of ice. For experiments with a low ratio of velocity to indentor showed damaged-enhanced creep behaviour, ending in large, global failure during some tests. For the highest velocity tests, the ice showed increasingly brittle failure. The loading curve in these tests displayed many smaller spalling events, or ice extrusion events, with cyclic ramp-up of loads between each event.