Dynamics of viscoplastic deformation in amorphous solids
Dynamics of viscoplastic deformation in amorphous solids
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DOI：
10.1103/physreve.57.7192
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发表时间：
1998-06-01
影响因子：
2.4
通讯作者：
Langer, JS
中科院分区：
文献类型：
--
作者：
Falk, ML;Langer, JS
本文提出了一个非晶固体低温剪切变形的动力学理论。我们的分析是基于分子动力学模拟的二维，两个组件的非晶态系统。这些数值模拟揭示了典型的金属玻璃和其他粘塑性材料的行为，具体地说，可逆的弹性变形在小的施加应力，不可逆的塑性变形在较大的应力，应力阈值以上的无界塑性流动发生，和强烈的依赖性的系统的状态的历史上过去的变形。微观观察表明，一个动态完整的描述，这种变形体的宏观状态需要指定，除了应力和应变，某些平均功能的人口的两个状态的剪切转变区。我们将这些状态变量引入到该系统的本构方程中，是早期金属玻璃蠕变模型的扩展。在这里提出的治疗，我们专门的温度远低于玻璃化转变和假设，不可逆的运动是由当地的熵波动的体积的转变区。在大多数方面，我们的理论与模拟中看到的各种各样的现象有很好的定量一致性。
We propose a dynamical theory of low-temperature shear deformation in amorphous solids. Our analysis is based on molecular-dynamics simulations of a two-dimensional, two-component noncrystalline system. These numerical simulations reveal behavior typical of metallic glasses and other viscoplastic materials, specifically, reversible elastic deformation at small applied stresses, irreversible plastic deformation at larger stresses, a stress threshold above which unbounded plastic flow occurs, and a strong dependence of the state of the system on the history of past deformations. Microscopic observations suggest that a dynamically complete description of the macroscopic state of this deforming body requires specifying, in addition to stress and strain, certain average features of a population of two-state shear transformation zones. Our introduction of these state variables into the constitutive equations for this system is an extension of earlier models of creep in metallic glasses. In the treatment presented here, we specialize to temperatures far below the glass transition and postulate that irreversible motions are governed by local entropic fluctuations in the volumes of the transformation zones. In most respects, our theory is in good quantitative agreement with the rich variety of phenomena seen in the simulations.