材料期刊网

INFLUENCE OF AGING ON MICROSTRUCTURE AND TENSILE BEHAVIOR OF Al ALLOY 8090

JIANG Daming , SUN Fenglian , HONG Bandc , LEI TingquanHarbin Institute of Technology , Harbin , ChinaDOWNHAM D A , LORIMER G WUniversity of Manchester , UK

金属学报(英文版)

The variations of microstructure and tensile behavior of an Al-Li-Cu-Mg-Zr alloy during aging are studied in this paper. It has been found that the fine δ-phase precipitated in the underaging condition and that the δ-, S-and T1-phases precipitate in the peak aging and the overaging conditions. The alloy exhibits transgranular fracture on the underaging condition, and mixture of transgranular and intergranular ruptures in the peak aging and overaging conditions.

关键词: A1 alloy 8090 , null , null , null

Ion sputter erosion in metallic glass-A response to "Comment on: Homogeneity of Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass" by L-Y. Chen, Y-W. Zeng, Q-P. Cao, B-J. Park, Y-M. Chen, K. Hono, U. Vainio, Z-L. Zhang, U. Kaiser, X-D. Wang, and J-Z Jiang J. Mater. Res. 24, 3116 (2009)

Journal of Materials Research

The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.

关键词: room-temperature

Shape-Memory Intermetallics Development in Taiwan

S.K.Wu(Institute of Materials Science and Engineering , National Taiwan University Taipei , Taiwan 106 , China) H.C. Lin(Department of Materials Science , Feng-Chia University. Taichung. Taiwan 407. China)

金属学报(英文版)

In Taiwan, many groups engage in the development of TiNi SMAs. The two-stage martensitic transformations of and have been clarified for both TiNi binary and ternary alloys. The deformation behaviors have been investigated by cold-rolling, hot-rolling and wire drawing. Both shape memory effect and pseudoelasticity can be improved by some thermal-mechanical treatments. The damping characteristics of TiNi and TiNiX SMAs have also been systematically studied. Both B19'/B19 martensite (M)and R-phase(R) have high daming capacities due to the stress-induced movement of twin boundaries. Meanwhile, the addition of third elements-Fe and Cu-can largely increase the damping capacity.Recently, some high temperature shape memory alloys-TiHiPd and TiNi-.Au alloys-have also been intensively studied in Taiwan. All these potential investigations on the TiNi SMAs in Taiwan have attracted much attention and their important characteristics will be applied widely in the near future.

关键词: : TiNi shape memory alloys. research and development in Taiwan

基于粒子群和有限元的材料本构模型参数的确定

倪永中 , 徐鸿

材料科学与工程学报

本文提出了一种基于粒子群算法和有限元方法的弹塑性本构方程参数的确定方法,并在此基础上开发了参数自动优化系统CMPI(Constitutive Material Parameter Identification).通过使最小二乘形式的目标函数达到极小值,实现参数的动态寻优;模型参数作为粒子群优化模块的输入,采用应变(应力)控制方法,调用材料非线性有限元模块计算特定参数时的应力(应变)响应,并计算与实验数据的误差,从而实现优化过程.CMPI目前适用于A-F类模型(Chaboehe、Ohno-Wang、Jiang-Sehitoglu)的参数优化,以此为基础,不难扩展到其他材料模型.

关键词: 粒子群 , 材料非线性 , 有限元 , Ohno-Wang 模型

混杂CFRP/GFRP筋HPC梁的非线性梁壳组合单元研究

张剑 , 周储伟 , 雷笑 , 叶见曙 , 卓家寿

复合材料学报

对于混杂CFRP/GFRP筋高性能混凝土(HPC)梁,研究一种新的三维非线性梁壳组合单元,对HPC梁进行了全过程分析.引入实体退化壳单元理论,利用空间梁单元模拟预应力CFRP筋,并根据CFRP筋单元节点线位移和转角位移的协调性,推导CFRP筋单元对梁壳组合单元刚度矩阵的贡献,同时对GFRP筋和HPC梁采用分层壳单元模拟.并运用Jiang屈服准则、Madrid强化准则等描述混凝土的材料非线性,提出一种新的非线性梁壳组合单元,研制相应的三维非线性计算程序.计算结果与试验数据吻合良好,说明本文构造的非线性梁壳组合单元的正确性和研制程序的可靠性,以及混凝土材料非线性描述的合理性;采用组合单元能准确模拟CFRP筋的几何构形,能综合考虑其拉压弯剪性能,利于全面地反映配筋对结构的增强作用.

关键词: CFRP筋 , GFRP筋 , 梁壳组合单元 , HPC梁 , 材料非线性