基于离散位错动力学-晶体塑性有限元的密排六方金属力学响应各向异性与织构演变研究

This project aims to develop a multi-scale plasticity model for hexagonal close-packed (HCP) metals, by combining discrete dislocation dynamics (DDD) and crystal plasticity finite element (CPFE) methods at microscopic and mesoscopic scales, respectively. The DDD method is applied to simulate dislocation movements and interactions corresponding to different slip systems, using dislocation core structures and dislocation mobility derived from molecular dynamics simulations. The combined model DDD-CPFE is expected to incorporate deformation physics at different scales during finite deformation, while retaining computation accuracy and efficiency required by potential engineering applications. By comparing model calculations and experiments, we investigate the anisotropic mechanical response and crystallographic texture evolution as well as the underlying mechanisms during plastic deformation under linear and complex strain paths for pure Mg and Mg alloys, and explore the principles for controlling the deformation mechanisms during plastic deformation of HCP metals. The theoretical and experimental results thus obtained may help improve the description of deformation mechanisms, microstructure and texture evolution, and macroscopic mechanical responses. The results are also expected to enrich and extend the theories as well as modeling and simulation techniques for plastic deformation of crystalline materials.

本项目拟选取密排六方（HCP）结构金属作为研究对象，借助分子动力学计算离散位错动力学（DDD）模拟所需位错芯结构及可动性，在晶体塑性有限元（CPFE）框架下引入DDD模拟位错组态演化及其相互作用，构建涵括纳观位错运动性质，以微观和细观层次耦合为主要特征的DDD-CPFE多尺度晶体塑性模型。该模型将进一步涵括有限变形微观物理本质，且具备潜在工程应用所需的计算精度和效率。结合模拟计算与实验，深入分析金属镁及镁合金在线性及复杂加载路径下的力学响应各向异性和晶体学织构演变及其机理，探讨材料塑性变形机制的调控原理。相关理论和实验成果的取得，有望更加准确刻画HCP金属塑性变形细观-微观变形机理及其对微观组织、织构演化及宏观力学响应的影响，丰富和发展晶体塑性变形理论和模拟方法。

本项目选取密排六方（HCP）结构金属作为研究对象，借助分子动力学计算离散位错动力学（DDD）模拟所需位错芯结构及可动性，在晶体塑性框架下引入DDD模拟位错组态演化及其相互作用所致应变硬化，构建涵括纳观位错运动性质，以微观和细观层次耦合为主要特征的DDD-VPSC多尺度晶体塑性模型。该模型进一步涵括了有限变形微观物理本质，且具备潜在工程应用所需的计算精度和效率。结合模拟计算与实验，分析了金属镁在典型加载路径下的力学响应各向异性和晶体学织构演变及其机理，探讨材料塑性变形机制的调控原理。研究表明，HCP镁不同类型位错的运动特性存在显著差异，且部分滑移系存在拉压非对称性。潜硬化贡献的相对大小本质上与位错微观结构的演化差异有关，并受到初始位错组态以及应变率的显著影响。在VPSC多晶塑性模型引入潜硬化参数可以提高织构演变的预测精度。相关理论和实验成果的取得，进一步揭示了HCP金属塑性变形细观-微观变形机理及其对微观组织、织构演化及宏观力学响应的影响，丰富和发展了晶体塑性变形理论和模拟方法。