The Dynamic Failure Behaviour of High-Pressure Zones during Medium-Scale Ice Indentation Tests

Featured Application The work presented here is valuable for estimating design loads for offshore structures operating in ice-prone regions, especially the ones susceptible to ice-induced vibrations. By exploring the effects of interaction speed, ice temperature, indenter size and structural compliance on failure behaviour, the work provides valuable insights into the dynamics of high-pressure zones (hpzs) during ice-structure interaction, which is essential for calculating dynamic ice load on offshore structures.Abstract Results from medium-scale ice-crushing dynamic tests are presented in this paper based on a series of indentation experiments on confined ice samples using spherical indenters to simulate high-pressure zones (hpzs) with areas on the order of 103-104 mm2. The effects of ice temperature, interaction speed, indenter size and structural compliance on failure behaviour and associated structural dynamics have been studied. Observed failure behaviour consisted of a combination of continuous crushing extrusion and intermittent spalling, both of which were highly dependent on test conditions. Overall, the effects of the studied conditions on ice failure behaviour and associated interaction dynamics were found to be similar to the results reported from previous small-scale experiments, suggesting scale independence of the mechanisms that dominate ice failure behaviour. In general, warmer ice and smaller contact areas are associated with continuous extrusion with intermittent spalling, resulting in smoother peak pressures, while colder ice and larger contact areas tend to result in fracture-dominated behaviour with sharp peaks and substantial load drops. Ice temperature was also found to significantly influence interaction dynamics, with colder ice showing larger amplitude and longer duration dynamic activity, and higher peak pressures. Interaction speed was observed to primarily affect dynamic aspects of ice-structure interactions, with faster tests leading to higher failure frequencies. Similarly, structural compliance was found to mainly impact failure frequency, as well as the extent of load drops, with compliant structures tending to produce more significant load drops following failure. Overall, these experiments have helped enhance our understanding of compressive ice failure and contribute to improved models for dynamic ice-structure interactions.