Search for Constitutive Relations for Micromechanics Modeling of Model Nanocrystalline Materials: A Multiscale Approach

摘要在过去的十年里，具有特征晶粒尺寸为1-100纳米的纳米晶体材料已经被合成和广泛研究。小尺寸的晶粒和大体积分数的原子坐在晶粒或界面边界的特点，这些材料。它们表现出许多不寻常的机械性能，使其成为迄今为止仅有的几种纳米材料系统之一，这些系统有可能用作民用，机械，运输和工业应用中的大规模结构材料。然而，随着晶粒尺寸的尺寸被推低到纳米尺度，在确定和理解机械性能及其与微观结构的关系方面的难度倍增。因此，各种力学性能的定量本构关系及其与微观结构的关系尚未完全建立。这项工作的目的是填补这一空白，在纳米晶材料中使用大规模的原子模拟的微观力学本构关系搜索。为了实现这一目标，我们计划进行大规模的原子模型的各种详细的微观结构和它们的贡献，在纳米环境中的本构关系。并对模型纳米晶样品的变形过程进行了连续模拟。在粗粒化建模中，将使用原子模拟得到的详细的本构关系和微观结构-性能关系。提出的主题是及时的，这些问题的答案是迫切需要的材料和力学社区。这项工作的成功实施，预计将有助于建立系统的方法来模拟微观结构，并奠定了坚实的基础，本构模型的机械变形在纳米多晶材料。

===========================ABSTRACT=============================Nanocrystalline materials with characteristic grain size of 1-100 nanometers have been synthesized and investigated extensively in the last decade. Small sized grains and large volume fraction of atoms sitting on grain or interface boundaries characterize these materials. They exhibit many unusual mechanical properties, making them by far one of only a few nanoscale material systems that have potential to be used as large-scale structural material in civil, mechanical, transport, and industrial applications. However, as the dimensions of the grain size are pushed down to nanometer scale, the degrees of difficulty multiply in determining and understanding the mechanical properties and their relations with microstructures. As a result, quantitative constitutive relations for various mechanical properties and their relation with microstructures have not been fully established. This work aims at filling this gap by searching for micromechanical constitutive relations in nanocrystalline materials using large-scale atomistic simulations. To achieve this goal, we plan to perform large-scale atomistic modeling of various detailed microstructures and their contributions to constitutive relations in nanoscale environment. And to perform continuum modeling of deformation process in model nanocrystalline samples. The detailed constitutive relation and microstructure-property relation obtained from atomistic simulations will be used in corse-grained modeling. The proposed topics are timely and answers to these questions are urgently needed for materials and mechanics community. Successful execution of this proposed work is expected to contribute to establishing systematic approaches for modeling microstructures and laying a solid foundation for constitutive modeling of mechanical deformation in nanoscale polycrystalline materials.