Weiguo Jiang
材料科学技术（英文）
A novel water-soluble core material composed of polyethylene glycol, sodium chloride, mica powder and plasticizer was prepared. The compressive strength, bend strength, hygroscopic coefficient and the material solubility in water were investigated. The results show that the compressive yield strength of the soluble core can reach 1 MPa and the highest compressive strength can reach 4 MPa, the bend strength is as high as 6.65 MPa, the hygroscopic coefficient is lower than 0.22%/month and the solubility of suitable core material is 35.7-55.75 g/(min·m2). The wax pattern with undercuts was prepared successfully by using the novel water-soluble core material.
关键词:
Investment cast
,
Core materials
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Mechanical property
,
Microstructure
Weiguo Jiang
材料科学技术（英文）
Four castings with different modulus have been designed to simulate different thickness sections of a turbine blade during casting process. The microstructure has been observed by optical microscopy (OM) and scanning electron microscopy (SEM). The micro-segregation was tested by energy dispersive spectroscopy (EDS) and the macro-segregation was analyzed by using Metalscan 2500 spectrometers. The experimental results show that the microstructure of casting is affected by modulus apparently. The smaller the modulus, the finer the microstructure. The average grain size of castings with modulus of 0.29, 1.57, 3.16 and 5.0 mm is 0.3, 1.5, 2.7 and 4.3 mm, and the volume fraction of eutectic is 0, 0.1%, 0.2% and 1.0%, respectively. The micro/macro segregation is affected by the modulus apparently. The smaller the modulus, the lower the segregation level. When the modulus of casting increases, the content of Al increases, while the content of W, Cr and Mo decreases both in inner grain and near grain boundary. The content of Al and Mo in inner grain is higher than that near grain boundary, while the content of Cr and W in inner grain is lower than that near grain boundary.
关键词:
Superalloy
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
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
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材料非线性
,
有限元
,
Ohno-Wang 模型
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
