Atomic nonaffinity as a predictor of plasticity in amorphous solids
Atomic nonaffinity as a predictor of plasticity in amorphous solids
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DOI：
10.1103/physrevmaterials.5.025603
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发表时间：
2019-05
影响因子：
3.4
通讯作者：
Bin Xu;M. Falk;S. Patinet;P. Guan
中科院分区：
文献类型：
--
作者：
Bin Xu;M. Falk;S. Patinet;P. Guan
无定形固体的结构不均匀性提出了困难的挑战，阻碍了预测塑性事件，这是密切相关的力学行为。基于微扰分析的势能景观，我们推导出原子的非亲和性作为一个指标与内在的方向，量化的贡献，单个原子的总非仿射模的系统。我们发现，原子非亲和性可以有效地表征剪切转变区的位置，预测能力媲美最好的指标。更重要的是，原子的非亲和性，结合能量的三阶导数的符号相对于坐标，揭示了一个内在的最软的剪切取向。通过分析这个方向和剪切加载方向之间的角度，可以预测塑性事件的协议相关响应。利用这种新方法，可以测量二维非晶固体模型中剪切转变区的取向分布。由此产生的塑性事件可以理解从一个简单的模型，独立的塑性事件发生在不同取向的剪切转变区。这些结果揭示了表征和预测的机械响应的无定形固体。
Structural heterogeneity of amorphous solids present difficult challenges that stymie the prediction of plastic events, which are intimately connected to their mechanical behavior. Based on a perturbation analysis of the potential energy landscape, we derive the atomic nonaffinity as an indicator with intrinsic orientation, which quantifies the contribution of an individual atom to the total nonaffine modulus of the system. We find that the atomic nonaffinity can efficiently characterize the locations of the shear transformation zones, with a predicative capacity comparable to the best indicators. More importantly, the atomic nonaffinity, combining the sign of third order derivative of energy with respect to coordinates, reveals an intrinsic softest shear orientation. By analyzing the angle between this orientation and the shear loading direction, it is possible to predict the protocol-dependent response of plastic events. Employing the new method, the distribution of orientations of shear transformation zones in a model two-dimensional amorphous solids can be measured. The resulting plastic events can be understood from a simple model of independent plastic events occurring at variously oriented shear transformation zones. These results shed light on the characterization and prediction of the mechanical response of amorphous solids.