基于熔核直径的车体高应力点焊接头疲劳性能优化试验研究  

Experimental Research on Optimizing the Fatigue Performance of High Stress Spot Welded Joints of Carbody Based on Nugget Diameter

作　　者：韩晓辉[1] 刘胜龙[1] 赵延强[1] 

机构地区：[1]南车青岛四方机车车辆股份有限公司,山东青岛266000

出　　处：《中国铁道科学》2013年第6期84-88,共5页China Railway Science

基　　金：国家"八六三"计划项目(2008AA030702)

摘　　要：针对轨道不锈钢车体结构中呈高应力状态的侧墙板与底架边梁、侧墙梁柱横梁与立柱以及底架边梁与横梁连接处的点焊接头,采用不同工艺参数制备熔核直径分别为5δ,6δ和7δ(δ为点焊接头薄板的板厚)的3组点焊接头试件;采用拉伸剪切试验、疲劳试验和升降法测定点焊接头试件的拉伸剪切强度和疲劳性能,并从点焊接头试件熔核直径与等效应力强度因子的关系,研究不同熔核直径及点焊工艺对不锈钢车体高应力点焊接头疲劳性能的影响,以获得疲劳性能最优的点焊接头结构和点焊工艺参数。研究结果表明:点焊接头的拉伸剪切强度随熔核直径的增大而增加,等效应力强度因子随熔核直径的增大而减小,熔核直径的增加对延长点焊接头疲劳寿命的作用不明显;熔核直径为6δ时,点焊接头试件的焊接工艺和疲劳应力参数匹配最合理,疲劳性能和可靠性最优。Three sets of bearing high stress spot welded joints connecting side-wall panel and side-beam of base-chassis, beam and column of side-walls, as well as crossbeam and side-beam of base-chassis, which carry high stress in railway stainless steel carbody, were selected as investigation objects. The welded specimens with nugget diameters of 5√δ, 6√δ and 7√δ were prepared using different spot welding parameters for the three sets of joints （8 is for the thickness of the thinner plate of spot welded joints）, and the tensile-shear strength and fatigue performance of each specimen were investigated by tensile-shear tests, fatigue tests and up-down method. Based on the relationship between nugget diameter and the equivalent stress intensity factor, the influences of different nugget diameters and spot welding process on the fatigue performances of high stress spot welded joints were studied, so as to optimize the struetures of spot welded joints and the parameters of spot welding process. The results show that the tensile-shear strengths of three sets of spot welded joints consecutively increase, but the equivalent stress intensity factors decrease with the increase of nugget diameter. The increase of nugget diameter doesn＇t have distinct effect on prolonging the fatigue life of spot welded joint. The matching between welding process and stress parameters is the most reasonable for the specimen with nugget diameter 6√δ, and the fatigue performance and reliability are optimal.

关 键 词：点焊接头 熔核直径 疲劳寿命 拉伸剪切强度 

分 类 号：U270.32[机械工程—车辆工程] TG407[交通运输工程—载运工具运用工程]