The Impact of Cyclic Loading on the Flexural Strength of Ice

Flexural strength measurements of sea ice in far inlying regions can experience continuous cyclic loading due to wave interactions. Furthermore, global warming leads to a continuous decrease of the Polar ice masses, resulting in an increased vulnerability of the integrity of the ice and its exposure to wave interactions and in consequence a growth of the marginal ice zone. In order to investigate the impact of cyclic loading on the flexural strength of ice, experiments with periodically loaded and previously unloaded ice samples is performed and analyzed. Previous research indicated both a weakening and a strengthening of the ice and the scope of this paper is also to enhance the understanding of the impact of cyclic loading of ice. This is relevant as ice might be subjected to several loading cycles before wave induced break-up and the question is whether the impact of cyclic loading needs to be accounted for in models. of its impact is addressed. The results show that the flexural strength of periodically loaded samples increases instead of fatigueing. Furthermore the ice has a very dynamic behaviour even at very low loading frequencies and small displacement-amplitudes in the micrometre range.