Behavior Under Cyclic Loading of Freshwater Ice and Sea Ice With Thermal Microcracks
Behavior Under Cyclic Loading of Freshwater Ice and Sea Ice With Thermal Microcracks
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DOI：
10.1029/2023gl102889
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发表时间：
2023-05
影响因子：
5.2
通讯作者：
A. Murdza;E. Schulson;C. Renshaw
中科院分区：
文献类型：
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作者：
A. Murdza;E. Schulson;C. Renshaw
薄冰，较大的波浪，以及由于昼夜热循环造成的损害的组合，促使需要更好地了解在海浪作用下弯曲对热裂冰强度的影响。为此，在淡水、实验室培育的冰和第一年的天然海冰上进行了新的实验。两种材料均因热冲击而开裂，随后循环弯曲。最初，热裂纹削弱了两种材料。当两种来源的裂纹冰在完全反向载荷下循环弯曲时，其弯曲强度最初因裂纹的应力集中作用而降低，恢复到无裂纹、无弯曲冰的强度。当破裂的冰被非弹性地循环弯曲时，其强度仅部分恢复。在反向循环屈曲过程中，裂纹区经历交替的压应力和拉应力。我们建议压缩导致接触的相对裂纹面随后烧结导致强度恢复。在非反向循环弯曲过程中，接触和烧结减少，冰强度没有完全恢复。裂缝在周期性弯曲过程中愈合的趋势可能会减少它们对冰盖结构完整性的威胁。
The combination of thinning ice, larger waves, and damage due to diurnal thermal cycling motivate the need to better understand the impact of flexing under the action of oceanic waves on the strength of thermally cracked ice. To that end, new experiments were performed on freshwater, lab‐grown ice and first‐year natural sea ice. Both materials were cracked by thermal shocking and then subsequently cyclically flexed. Initially, the thermal cracks weakened both materials. When the cracked ice of either origin was cyclically flexed under fully reversed loading, its flexural strength, initially reduced by the stress‐concentrating action of the cracks, recovered to the strength of non‐cracked, non‐flexed ice. When the cracked ice was cyclically flexed non‐reversely, its strength recovered only partially. During reversed cyclic flexing, the cracked region experienced alternately compressive and tensile stresses. We suggest compression resulted in contact of opposing crack faces followed by sintering leading to strength recovery. During non‐reversed cyclic flexing, contact and sintering were reduced and ice strength did not fully recover. The tendency for cracks to heal during cyclic flexing may lessen their threat to the structural integrity of an ice cover.