项目名称: 微尺度下材料循环塑性行为及其理论模型研究
项目编号: No.11202172
项目类型: 青年科学基金项目
立项/批准年度: 2013
项目学科: 数理科学和化学
项目作者: 张旭
作者单位: 西南交通大学
项目金额: 24万元
中文摘要: 针对微尺度下材料循环塑性行为研究的不足,特别是表面和界面对微尺度循环塑性行为的影响,建立考虑表面效应和界面效应的离散位错动力学模拟框架和应变梯度塑性理论模型,进而来研究微尺度下材料循环塑性行为的表面和界面效应。通过离散位错动力学模拟,了解循环塑性变形过程中位错微结构演化规律,并讨论表面和界面对位错微结构演化的影响,揭示循环塑性变形的微观机理。基于离散位错动力学模拟所揭示的位错微结构演化规律,建立內禀材料长度和背应力演化方程与位错微结构演化之间的联系,进而发展有物理基础的应变梯度循环塑性本构理论.新发展的离散位错动力学模拟框架和应变梯度塑性本构理论将用于材料循环塑性变形的包辛格效应、循环强化/软化和棘轮效应的研究,并与现有的实验进行对比。研究结果将会丰富微尺度下材料循环塑性行为的认识,具有重要的理论意义;也将用于微结构器件的性能优化、安全设计和寿命评估,具有广阔的工程应用前景。
中文关键词: 循环;应变梯度;离散位错;表面与界面;內禀长度尺度
英文摘要: Aiming at the research on cyclic plasticity behavior of materials at microscale is insufficient, especially the influence coming from the surface and interface of the materials, we will establish the discrete dislocation dynamics simulation framework and strain gradient plasticity model by considering the surface effect and interface effect, and then to study cyclic plasticity behavior of materials at microscale. Through the discrete dislocation dynamics simulation, we could explore the evolution of dislocation microstructure and the influence coming from the surface and interface, revealing the underlying deformation mechanism in cyclic plasticity. Based on the microstructure evolution information revealed by discrete dislocation dynamics simulation, we will establish a connection between the intrinsic material length, back stress evolution equations and the evolution of dislocation microstructure, and thus construct a strain gradient plasticity constitutive model with physical foundation. In the end, we will conduct the study on the cyclic plasticity behavior, such as Bauschinger effect, cyclic hardening/softening and ratcheting effect, by using the new updated discrete dislocation simulation framework and strain gradient plasticity model, and the results will then be compared with the existed experiments. Th
英文关键词: cyclic;strain gradient;discrete dislocation dynamics;surface / interfade;internal length scale