Hierarchical Modeling of Crystal Deformation

在分析材料的热物理性质时，有一组重要的问题围绕着如何在理解材料内部发生的潜在缺陷机制的基础上进行分析。例如，在塑性变形的背景下，尽管众所周知，塑性通常是由位错的运动介导的，但到目前为止，直接基于位错物理构建塑性模型的目标在很大程度上尚未实现。这样做的部分原因是在这种多长度和时间尺度的问题中的操作。这里提出的工作有两个重点：1)开发新的计算工具来研究涉及长度和时间尺度层次的问题；2)应用这些层次工具来分析位错的成核、运动和相互作用。我们的方法学工作将集中于将准连续体方法扩展到三维，具有在有限温度下进行动态模拟的完整能力，并包括网格细化和网格粗化。这些思想在位错物理学中的应用将包括对位错运动动力学和结强度的分析

9971922Phillips An important set of problems in the analysis of the thermophysical properties of materials surround the question of how to base this analysis on an understanding of the underlying defect mechanisms taking place within a material. For example, in the context of plastic deformation, though it is well known that plasticity is often mediated by the motion of dislocations, as yet, the goal of constructing models of plasticity based directly on the physics of dislocations has been largely unfulfilled. Part of the reason for this is the operation in problems of this sort of multiple length and time scales. The work proposed here has two key thrusts: 1) the development of new computational tools for the investigation of problems involving a hierarchy of length and time scales and 2) the application of these hierarchical tools to the analysis of the nucleation, motion and interaction of dislocations. Our methodological work will center on the extension of the quasicontinuum method to three-dimensions with a full capability for carrying out dynamical simulations at finite temperature and including both mesh refinement and mesh coarsening. The application of these ideas to the physics of dislocations will include an analysis of the kinetics of dislocation motion and the strength of junctions