Experiments on the fracture of polycrystalline ice
Results are presented for a series of indentation tests that were designed to study ice failure processes under varying loading conditions. A high-speed video camera was used to link load trace events (i.e. load spikes and drops, etc) with failure processes. It was shown that large-scale fractures a...
| Main Authors: | , , , |
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| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
2007
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| Subjects: | |
| Online Access: | https://nrc-publications.canada.ca/eng/view/object/?id=e7d322dc-9e61-409c-8111-41352662c30f https://nrc-publications.canada.ca/fra/voir/objet/?id=e7d322dc-9e61-409c-8111-41352662c30f |
| Summary: | Results are presented for a series of indentation tests that were designed to study ice failure processes under varying loading conditions. A high-speed video camera was used to link load trace events (i.e. load spikes and drops, etc) with failure processes. It was shown that large-scale fractures and spalls are directly correlated with significant drops in load. Thin-sectioning of the samples showed the existence of a damaged layer of ice during testing. Micro-cracking, crushing, and recrystallization were all present in a zone beneath the indenter. This is consistent with the current description of a high-pressure zone, providing confidence in the current ice-structure interaction models understanding the role played by such mechanical processes as large-scale fracture, spalling, and damage on global load reduction. During an ice-structure interaction the majority of the force will be transferred to the structure through a series of relatively small zones of high pressure (HPZs). These HPZs vary in both time and location throughout the interaction (Fig. 1 (a)). They are influential in the evolution of the interaction since their presence is linked to localized spalling, large-scale fracture, damage and softening of ice in the interaction area. When the HPZ occurs near the edge of an ice-sheet large-scale fractures can be precipitated. These fracture events significantly reduce the load that is felt by the structure (Jordaan, 2001). In the vicinity of the HPZs, damaged ice forms in a layer as shown in Fig. 1 (b). In the center of the HPZ, where the confining pressures are highest, the damaged layer likely consists of a region of recrystallized and pressure. Peer reviewed: Yes NRC publication: Yes |
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