冷弯薄壁型钢结构受剪性能影响因素研究

采用了有限元法对冷弯薄壁型钢单榀墙架结构的进行受剪性能的分析。建立模型时同时考虑材料和几何非线性,采用弹塑性189梁单元,自攻螺栓采用耦合模型。通过改变已建立的有限元模型中墙架柱间距、墙架高宽比、自攻螺丝间距等影响墙架受剪性能的参数,得出结论:随着墙架柱间距增大、墙架高度增大、自攻螺栓间距增大整个墙架结构的受剪性能明显减小,在有"K"型支撑的高强薄壁型钢墙架结构中,合适的墙架柱间距、合适的墙架尺寸以及支撑体系,对墙架结构的受剪性能有很大的影响。     

薄壁零件的工艺分析

论述了在数控车床上加工薄壁零件时,如何针对零件特点优化加工工艺、制作专用的工装等工艺措施来提高产品合格率,并对工艺改进前后的零件质量进行比对分析.     

Experimental and Numerical Research on Deformation Behavior of Thin-Walledand Large Expansion Ratio Guide Vane Liner in Hydroforming Process

Some tube hydroforming process tests and further research work were conducted to manufacture hollow guide vane liners (made of super alloy GH3030).The relative thickness (t₀/OD) of the tubular blank is approximately 0.01,and the maximum expansion ratio (Dmax/OD) of the needed part is more than 40％, and the length to diameter ratio of the expansion regionis more than 3.0. It is very hard to manufacture this kind of ultra-thin-wall, curved axis and large expansion ratio tubular part without fracture and wrinkles. The success of the process is highly dependent on useful wrinkles with appropriate internal pressure and axial feeding. A simplified finite element model and a theoretical model are used for detecting the deformation behavior and forming laws. Further study results demonstrate that the useful wrinkles do not appear at the same time and middle-wrinkles need bigger axial force than tube-end-wrinkles and feeding-wrinkles. The wrinkles can transfer bigger axial force after its wave peak has come into contact with the die inner surface. The thickness thinning rate of the element at the peak is bigger than that at the trough.With the increase of the axial and hoop stress ratio, the critical buckling stress also increases. Microstructure examination results show that the grain size in the maximum thinning zone has been stretched and refined after the large deformation and annealing treatment. The process is feasible and the finished part is qualified.