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arXiv 1402.4655cond-mat.soft
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无序固体中流动的粗粒模型中的普适和非普适特征

Universal and non-universal features in coarse-grained models of flow in disordered solids

Alexandre Nicolas, Kirsten Martens, Lydéric Bocquet, Jean-Louis Barrat

摘要:

我们研究了弹塑性模型中非晶态固体的二维剪切流动,特别注意空间相关性和时间波动,例如,局部压力。该模型是基于局部交替之间的弹性制度和塑性事件,在此期间,局部应力重新分布。一个完全张量描述的应力和列入(粗粒)对流模型的重要性进行了研究;标量和张量模型产生非常相似的结果,而对流增强波动和打破虚假的对称性之间的流动和速度梯度方向,例如当剪切局部化观察。此外,还讨论了使用不同协议测量的相关长度。一类这样的相关长度简单地与均匀分布的,同时发生的塑性事件之间的间距成比例。这导致相关长度与剪切速率的缩放,如$\dotγ^{\frac{-1}{2}}$在2D中的无热状态,而不管模型的细节。合作盘的半径,定义为近场区域中,塑性事件引起的应力重新分布,是不服从平均场治疗,特别是遵循这种缩放。另一方面,从四点应力敏感性测量的合作体积及其对系统尺寸和剪切速率的依赖性是模型依赖性的。

英文摘要:

We study the two-dimensional (2D) shear flow of amorphous solids within variants of an elastoplastic model, paying particular attention to spatial correlations and time fluctuations of, e.g., local stresses. The model is based on the local alternation between an elastic regime and plastic events during which the local stress is redistributed. The importance of a fully tensorial description of the stress and of the inclusion of (coarse-grained) convection in the model is investigated; scalar and tensorial models yield very similar results, while convection enhances fluctuations and breaks the spurious symmetry between the flow and velocity gradient directions, for instance when shear localisation is observed. Besides, correlation lengths measured with diverse protocols are discussed. One class of such correlation lengths simply scale with the spacing between homogeneously distributed, simultaneous plastic events. This leads to a scaling of the correlation length with the shear rate as $\dotγ^{\frac{-1}{2}}$ in 2D in the athermal regime, regardless of the details of the model. The radius of the cooperative disk, defined as the near-field region in which plastic events induce a stress redistribution that is not amenable to a mean-field treatment, notably follows this scaling. On the other hand, the cooperative volume measured from the four-point stress susceptibility and its dependence on the system size and the shear rate are model-dependent.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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