Ice; Ice strength; Ice force; Ice impact; High strain rate; Ice compressive strength; Ice temperature effects; Ice dynamic response

摘要

High strain rate compression tests were conducted with columnar ice grown in the laboratory. In addition to measuring stress and strain to failure at two strain rates, we examined the effects of end conditions on the failure process. Experiments were performed in a split Hopkinson pressure bar at two temperatures, -10 °C and -40°C, and a strain rate in the range of 10 to 15 s{sup}(-1). Additional experiments were performed on similarly grown ice at a lower strain rate of 3 × 10{sup}(-4) s{sup}(-1) for comparison. In the high strain rate tests, the general observation is that most failures occurred by splitting, and the final failure by collapse of the columns, which become unstable under the sustained load during the passage of the stress wave. Most failures occurred around a value of 1000 microstrain. After crack initiation, failure is progressive, with multiple peaks in the stress-time history, and it takes a finite time for ejection of fragments before the final collapse. Reduction of temperature increases the peak stress values. We also note that although the initial fracture is brittle in nature the final failure, or collapse, because of time for the fragment ejection, gives the appearance of visco-elastic failure.