Gang LIU
,
Xuelian YIN
,
Shijian YUAN
材料科学技术（英文）
Buckling and forming processes of tubes with varying slenderness ratio (ratio of length to diameter) under external hydraulic pressure were analyzed with three-dimensional finite element method (FEM) for studying tube external pressure forming (EPF). Buckling pressures for different tube blanks without mandrel were predicted, and an EPF of a carbon steel tube onto a mandrel with six ribs was simulated. Both thickness distribution and buckling pressure from the simulations were found to be in agreement with those from experiments. Buckling pressures are shown to be a function of the slenderness ratio. The tubular part with six ribs produced by EPF has a uniform thickness distribution, whose maximum thinning rate is only 5.9%.
关键词:
External pressure forming
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庄厚龙
,
彭平
,
周惦武
,
刘金水
稀有金属材料与工程
采用第一原理赝势平面波方法--CASTEP程序计算了4种B2型Y基金属间化合物YX(X=Ag,Cu,In,Rh)的部分弹性性质,计算结果与文献报道值基本一致.通过Pugh定律、Cauchy压力和泊松比等经验判据,分析并预测了它们的脆性/延性,其延性高低次序为:YRh＞YAg＞YCu＞YIn.电子结构分析表明:这4种金属间化合物良好的延性源于其较强的金属键,而不同程度的Y(d)-X(p)电子杂化则导致了其延性的差异.YIn中因In的p电子较多,杂化程度高,共价键方向性强,因而延展性最低,而YRh则由于存在Y(d)-Rh(d)电子间强的相互作用,增强了其金属键作用,因而延性最好.
关键词:
Y基金属间化合物
,
脆性/延性
,
第一原理
,
电子结构
