门式起重机焊接箱形梁上盖板疲劳裂纹形成机理研究  

Forming Mechanism of the Fatigue Crack of a Upper Plate in a Gantry Crane Welding Box Girder

作　　者：付为刚[1] 程文明[1] 濮德璋[1] 王弘[2] 郑严[1] 

机构地区：[1]西南交通大学机械工程研究所 [2]西南交通大学力学工程学院,成都610031

出　　处：《机械科学与技术》2011年第5期746-750,共5页Mechanical Science and Technology for Aerospace Engineering

基　　金：中央高校基本科研业务费专项资金(2010ZT03)资助

摘　　要：门式起重机焊接箱型梁上盖板疲劳裂纹的形成过程复杂,疲劳裂纹形成影响因素多。从门式起重机箱型梁的焊接工艺特性出发,分析焊缝处的残余应力;从起重机实际工况出发,将箱型梁对轨道的支撑作用简化为主腹板(弹性地基)对轨道的支撑作用,分析了焊缝处的载荷特征;从焊接断裂力学角度,分析了焊缝处疲劳裂纹萌生点及疲劳裂纹的扩展过程。研究结果表明:疲劳裂纹萌生点为三角肋板角点处;纵向裂纹萌生的主要原因是小车轮压作用引起的交变剪应力;横向裂纹形成的主要原因是箱型梁弯曲切应力、主焊缝横向残余应力、加劲肋板焊缝方向残余应力和焊接热影响区材料特性的共同作用。The forming process of the fatigue crack of the upper plate in the gantry crane welding box girder is complicated.According to the welding process characteristic of the gantry crane box girder,the residual stress in the weld joint was analyzed in this paper.To analyze the load characteristic of the weld joint,the rail′s support from the box girder was simplified as the support from the main web by the crane′s practical working condition.The weld crack mechanics theory was used to analyze the crack initiation site and the fatigue crack development process.Results show that（1） the crack initiation site is the triangular gusset welded point;（2） the main initiation factor of the longitudinal crack is the alternation of tangential stress caused by the trolley;（3） the main forming factor of the transverse crack is the bending tangential stress in the box girder,the transverse residual stress in the main welding joint,the residual stress in the direction of the intensified plate welding joint and the material characteristic in the position caused by the welding heat.

关 键 词：焊接 疲劳裂纹 残余应力 断裂力学 

分 类 号：TH213.5[机械工程—机械制造及自动化]