Experimental Constraints on the Fatigue of Icy Satellite Lithospheres by Tidal Forces
Experimental Constraints on the Fatigue of Icy Satellite Lithospheres by Tidal Forces
复制标题
潮汐力对冰卫星岩石圈疲劳的实验约束
DOI：
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
G. Hirth
中科院分区：
文献类型：
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作者：
N. Hammond;A. Barr;R. Cooper;T. Caswell;G. Hirth
疲劳可以使承受循环载荷的材料在比单调载荷下低得多的应力下经历脆性破坏。我们认为，冰卫星的岩石圈可能会因周期性潮汐应力而变得疲惫，从而减弱。为了验证这一假设，我们进行了一系列实验室实验，以测量水冰在198K和233K温度和1赫兹加载频率下的疲劳。我们发现，在我们的实验条件下，冰是不容易疲劳的，并且脆性破坏应力并不随着加载循环次数的增加而减小。尽管在我们的实验条件下没有观察到疲劳，但较低的温度、较低的加载频率和结冰卫星冰壳中的杂质可能会增加疲劳裂纹扩展的可能性。我们还探索了其他机制，可以解释一些结冰卫星的岩石圈的微弱行为。
Fatigue can cause materials that undergo cyclic loading to experience brittle failure at much lower stresses than under monotonic loading. We propose that the lithospheres of icy satellites could become fatigued and thus weakened by cyclical tidal stresses. To test this hypothesis, we performed a series of laboratory experiments to measure the fatigue of water ice at temperatures of 198 K and 233 K and at a loading frequency of 1 Hz. We find that ice is not susceptible to fatigue at our experimental conditions and that the brittle failure stress does not decrease with increasing number of loading cycles. Even though fatigue was not observed at our experimental conditions, colder temperatures, lower loading frequencies, and impurities in the ice shells of icy satellites may increase the likelihood of fatigue crack growth. We also explore other mechanisms that may explain the weak behavior of the lithospheres of some icy satellites.