Plasticity without phenomenology: A first step
Plasticity without phenomenology: A first step
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没有现象学的可塑性：第一步
DOI：
10.1016/j.jmps.2020.104059
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发表时间：
2020
影响因子：
5.3
通讯作者：
Ghoniem, Nasr
中科院分区：
文献类型：
--
作者：
Chatterjee, Sabyasachi;Po, Giacomo;Zhang, Xiaohan;Acharya, Amit;Ghoniem, Nasr
展示了一种新的、并行的多尺度方法来研究中观/宏观尺度塑性。它采用了精心设计的基于偏微分方程（pde）的位错介导晶体塑性理论与微观位错动力学（DD）的时间平均输入的耦合，采用了最先进的数学粗粒化方案。细观样品在真实、缓慢、加载速率可达可观应变值时的应力应变响应，与传统的DD相比，计算时间显著加快。在加载和位移控制的模拟中，证明了晶体取向、加载速率和初始移动位错密度与固位错密度之比对宏观响应的影响。这些结果是在没有使用任何现象学本构假设的情况下获得的，除了热激活，这不是微观DD的一部分。结果还证明了内应力对位错集体行为的影响，在一组例子中表现为阶段I到阶段II的硬化转变。
A novel, concurrent multiscale approach to meso/macroscale plasticity is demonstrated. It utilizes a carefully designed coupling of a partial differential equation (pde) based theory of dislocation mediated crystal plasticity with time-averaged inputs from microscopic Dislocation Dynamics (DD), adapting a state-of-the-art mathematical coarse-graining scheme. The stress-strain response of mesoscopic samples atrealistic, slow, loading rates up to appreciable values of strain is obtained, with significant speed-up in compute time compared to conventional DD. Effects of crystal orientation, loading rate, and the ratio of the initial mobile to sessile dislocation density on the macroscopic response, for both load and displacement controlled simulations are demonstrated. These results are obtainedwithout using any phenomenological constitutive assumption, except for thermal activation which is not a part of microscopic DD. The results also demonstrate the effect of the internal stresses on the collective behavior of dislocations, manifesting, in a set of examples, as a Stage I to Stage II hardening transition.