The microstructural origin of strain hardening during plastic deformation in stage II deformation of face-centered cubic (fcc) metals can be attributed to the increase in dislocation density resulting in a formation of dislocation networks. Although this is a well known relation, the complexity of dislocation multiplication processes and details about the formation of dislocation networks have recently been revealed by discrete dislocation dynamics (DDD) simulations. It has been observed that dislocations, after being generated by multiplication mechanisms, show a limited expansion within their slip plane before they get trapped in the network by dislocation reactions. This mechanism involves multiple slip systems and results in a heterogeneous dislocation network, which is not reflected in most dislocation-based continuum models. We approach the continuum modeling of dislocation networks by using data science methods to provide a link between discrete dislocations and the continuum level. For this purpose, we identify relevant correlations that feed into a model for dislocation networks in a dislocation-based continuum theory of plasticity. As a key feature, the model combines the dislocation multiplication with the limitation of the travel distance of dislocations by formation of stable dislocation junctions. The effective mobility of the network is determined by a range of dislocation spacings which reproduces the scattering travel distances of generated dislocation as observed in DDD. The model is applied to a high-symmetry fcc loading case and compared to DDD simulations. The results show a physically meaningful microstructural evolution, where the generation of new dislocations by multiplication mechanisms is counteracted by a formation of a stable dislocation network. In conjunction with DDD, we observe a steady state interplay of the different mechanisms.

中文翻译：

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位错网络的数据驱动探索和连续体建模

面心立方 (fcc) 金属第二阶段塑性变形过程中应变硬化的微观结构起源可归因于位错密度的增加导致位错网络的形成。尽管这是众所周知的关系，但最近通过离散位错动力学 (DDD) 模拟揭示了位错倍增过程的复杂性和有关位错网络形成的细节。已经观察到，位错在通过倍增机制产生后，在它们被位错反应困在网络中之前，在其滑移平面内显示出有限的扩展。这种机制涉及多个滑动系统并导致异质位错网络，这在大多数基于位错的连续介质模型中没有体现出来。我们通过使用数据科学方法来对位错网络进行连续建模，以提供离散位错和连续层之间的联系。为此，我们确定了相关的相关性，这些相关性可以输入基于位错的连续可塑性理论中的位错网络模型。作为一个关键特征，该模型通过形成稳定的位错结将位错倍增与位错行进距离的限制相结合。网络的有效迁移率由一系列位错间距决定，该范围再现了在 DDD 中观察到的生成位错的散射传播距离。该模型应用于高对称 fcc 载荷情况，并与 DDD 模拟进行比较。结果显示了具有物理意义的微观结构演变，其中通过倍增机制产生的新位错被稳定位错网络的形成所抵消。结合 DDD，我们观察到不同机制的稳态相互作用。