Predicting plastic events and quantifying the local yield surface in 3D model glasses
Predicting plastic events and quantifying the local yield surface in 3D model glasses
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DOI：
10.1016/j.jmps.2021.104671
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发表时间：
2021-10
影响因子：
5.3
通讯作者：
Dihui Ruan;S. Patinet;M. Falk
中科院分区：
文献类型：
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作者：
Dihui Ruan;S. Patinet;M. Falk
通过应用局部屈服应力（LYS）方法探测三维计算玻璃模型的局部区域，我们证实了当该方法的参数化适当优化时，测得的局部屈服应力（Δ τ c）与塑性事件之间的高度相关性。发现该系统的最佳探测区域为半径为1.5 σ，其中σ表示Lennard-Jones长度尺度，近似于原子尺寸。在前200个塑性事件或1/3的屈服应变（0.7%）中，平均相关性保持正相关。在这里，我们只应用与边界上的负载完美对齐的局部探测。LYS测量结果收敛于Weibull分布，在较大的探测区域半径处，最小Δ τ c与零不可区分。假设Δ τ c是一个在临界长度尺度上服从极值统计的局部量，对数据的分析将Δ τ c的潜在分布指数限制在1.26和1.71之间。在第一次塑性事件的位置的局部屈服面的各向异性的彻底调查表明，第一个触发区域不完全对齐的边界上的负载，但很好地预测，通过投影的剪切施加在边界上的局部屈服面。这意味着局部屈服应力预测和由此产生的塑性之间的相关性可以通过在每个样本点处对局部屈服面进行更完整的评估来增强。
By applying the local yield stress (LYS) method to probe local regions of three-dimensional computational glass models, we confirm high correlations between the measured local yield stress (Δ τ c) and the plastic events when the parameterization of the method is properly optimized. The optimal probing region for this system is found to be∼ 5 σ in radius, where σ represents the Lennard-Jones length scale, approximately the atomic size. The averaged correlation remains positive through the first 200 identified plastic events or 1/3 of the yielding strain (∼ 7%). Here we apply only the local probing that aligns perfectly with the loading on the boundary. The LYS measurements converge to a Weibull distribution with a minimum Δ τ c indistinguishable from zero at larger probing region radii. Analysis of the data in light of an assumption that Δ τ c is a local quantity that obeys extreme value statistics above a critical length scale bounds the exponent of the underlying distribution of Δ τ c to lie between 1.26 and 1.71. A thorough investigation of the anisotropy of the local yield surface at the location of the first plastic event indicates that the first triggered region does not align perfectly with the loading on the boundary, but is well-predicted by projecting the shear applied at the boundary onto the local yield surface. This implies that the correlation between the local yield stress prediction and the resulting plasticity may be enhanced by performing a more complete assessment of the local yield surface at each sample point.