In microscale deformation, the magnitudes of specimen and grain sizes are usually identical, and size- dependent phenomena of deformation behavior occur, namely, size effects. In this study, size effects in micro- cyl...In microscale deformation, the magnitudes of specimen and grain sizes are usually identical, and size- dependent phenomena of deformation behavior occur, namely, size effects. In this study, size effects in micro- cylindrical compression were investigated experimentally. It was found that, with the increase of grain size and decrease of specimen size, flow stress decreases and inhomogeneous material flow increases. These size effects tend to be more distinct with miniaturization. Thereafter, a modified model considering orientation distribution of surface grains and continuity between surface grains and inner grains is developed to model size effects in micro- forming. Through finite element simulation, the effects of specimen size, grain size, and orientation of surface grains on the flow stress and inhomogeneous deformation were analyzed. There is a good agreement between experimental and simulation results.展开更多
论文应用拓展的多尺度有限元法(Extended Multiscale Finite Element Method),以微观构件的截面积为设计变量,研究了体积约束下点阵材料构成结构的最小柔顺性设计问题.建立了适应具有复杂几何形状和载荷边界的点阵材料结构的优化模型,...论文应用拓展的多尺度有限元法(Extended Multiscale Finite Element Method),以微观构件的截面积为设计变量,研究了体积约束下点阵材料构成结构的最小柔顺性设计问题.建立了适应具有复杂几何形状和载荷边界的点阵材料结构的优化模型,应用序列二次规划算法对悬臂梁和L形梁算例在线性边界条件和周期性边界条件下进行了优化设计,讨论了点阵材料微结构尺寸效应对优化结果的影响,验证了优化模型和求解算法的可靠性,为点阵材料应用于复杂实际工程结构的优化设计提供了新的技术手段.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 50835002 and 51105102)
文摘In microscale deformation, the magnitudes of specimen and grain sizes are usually identical, and size- dependent phenomena of deformation behavior occur, namely, size effects. In this study, size effects in micro- cylindrical compression were investigated experimentally. It was found that, with the increase of grain size and decrease of specimen size, flow stress decreases and inhomogeneous material flow increases. These size effects tend to be more distinct with miniaturization. Thereafter, a modified model considering orientation distribution of surface grains and continuity between surface grains and inner grains is developed to model size effects in micro- forming. Through finite element simulation, the effects of specimen size, grain size, and orientation of surface grains on the flow stress and inhomogeneous deformation were analyzed. There is a good agreement between experimental and simulation results.
文摘论文应用拓展的多尺度有限元法(Extended Multiscale Finite Element Method),以微观构件的截面积为设计变量,研究了体积约束下点阵材料构成结构的最小柔顺性设计问题.建立了适应具有复杂几何形状和载荷边界的点阵材料结构的优化模型,应用序列二次规划算法对悬臂梁和L形梁算例在线性边界条件和周期性边界条件下进行了优化设计,讨论了点阵材料微结构尺寸效应对优化结果的影响,验证了优化模型和求解算法的可靠性,为点阵材料应用于复杂实际工程结构的优化设计提供了新的技术手段.
