某型地铁车辆车下帽型梁裂纹扩展寿命预测

Prediction of Crack Propagation Life of Cap Type Beam in a Subway Vehicle

针对某型地铁车辆车下帽型梁螺栓孔边开裂问题,本文通过统计大量开裂结构的裂纹情况,分析了裂纹分布规律,并利用有限元仿真技术探究导致帽型梁开裂的主要载荷;对送试验的5根帽型梁开展疲劳台架试验,并基于Paris公式和Minear线性损伤理论实现了该帽型梁裂纹扩展寿命的预测。研究结果表明:帽型梁结构的裂纹分布主要沿车身纵向,横向排布的帽型梁受横向振动的影响大,其次为垂向和纵向,垂向振动对纵向排布帽型梁的影响明显大于其余两向振动;5根帽型梁试样的剩余疲劳寿命均在1.07以上,与台架试验的结论相同,结构满足标准要求。

Aiming at the problem of the hole cracking of the capbeam under the type of subway vehicle,in this paper,the crackdistribution is analyzed by statistical analysis of the crack in a largenumber of cracked structures and the main load of the cap beam isstudied by using the finite element simulation technique.The fatiguebench test was carried out on the five cap beams,and the crackpropagation life of the cap beam was predicted based on the Parisformula and Minear linear damage theory.The results show that thecrack distribution of the cap beam structure is mainly along thelongitudinal direction of the vehicle body and lateral arrangement of thecap beam by the impact of lateral vibration.Followed by vertical andlongitudinal,vertical vibration on the longitudinal arrangement of capbeam effect was significantly greater than the other two-way vibration;the residual fatigue life of the five cap beam samples is above107,which is the same as that of the bench test,and the structure satisfiesthe standard requirement.The stress at the crack point of the cap beamis less than the fatigue limit of the material,and the crack source ismainly the initial defect.It is suggested to improve the hole drillingprocess of the cap beam and try to avoid the initial defect of thestructure.