剪切玻璃中疲劳失效时间的随机性
Stochasticity of fatigue failure times in sheared glasses
AI总结：
研究承受循环剪切变形的玻璃及弹塑性模型中疲劳失效时间分布，用计算机模拟发现失效时间对数标准差与平均值成正比，比例常数随系统尺寸变，分布源于失效过程内在随机性，通过随机损伤累积模型分析。
摘要：
疲劳失效发生在固体承受反复循环载荷时。最近通过计算机模拟和理论模型研究了承受循环剪切变形的玻璃，以表征和合理化失效循环次数与玻璃性质及变形幅度的关系。当应变幅度从上方接近所谓的疲劳极限时，平均失效循环次数会发散。本文通过计算机模拟研究了承受循环剪切变形的模型玻璃和弹塑性模型中疲劳失效时间的分布。在原子模拟中观察到失效时间对数的标准差与平均值成正比，比例常数随系统尺寸增加而减小。使用基于有限元的弹塑性模型也观察到类似行为，通过系统尺寸分析表明在热力学极限下标准差与平均值之比趋于零。这种分布似乎源于失效过程的内在随机性，通过随机损伤累积模型进行了分析。
英文摘要：
Fatigue failure occurs when a solid is subjected to repeated, cyclic loading. Glasses subjected to cyclic shear deformation have recently been investigated using computer simulations and theoretical models, to characterize and rationalize the dependence of the number of cycles to failure, depending on the properties of the glasses, and the deformation amplitude. The average number of cycles to failure has been observed to diverge as the strain amplitude approaches the so-called fatigue limit from above. In this work, rather than the average times themselves, we investigate by computer simulations the distribution of fatigue failure times, in model glasses subjected to cyclic shear deformation and in an elasto-plastic model. In particular, we observe in atomistic simulations that the standard deviation of the logarithm of failure times are proportional to their mean values, with the proportionality constant decreasing as the system size increases, indicating a sharper distribution of failure times. Using a finite-element-based elasto-plastic model, we observe similar behavior and perform a system-size analysis showing that the ratio of the standard deviation to the mean tends toward zero in the thermodynamic limit. Such distributions, rather than arising solely from the distribution of disorder in the samples that have been subjected to cyclic deformation, appear to arise from the intrinsic stochasticity of the failure process, which we analyze through a stochastic damage accumulation model.
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