某型地铁列车端部底架疲劳寿命研究

Study on End Underframe Fatigue Life of a Certain Type of Metro Train

[目的]地铁车体为焊接结构,受应力集中、焊接缺陷及焊接残余应力等影响,其车体疲劳强度会明显小于金属母材。而地铁列车端部底架作为转向架和车体相连接的部位,其承受的载荷相对更大,因此有必要研究其疲劳寿命。[方法]采用数值仿真和疲劳试验相结合的方法,对某型地铁列车端部底架常见的疲劳寿命问题进行研究。建立了地铁车辆有限元模型,确定了相应的疲劳载荷和评估点,对地铁车辆整车和端部底架分别进行了疲劳损伤仿真,对端部底架开展台架试验;并对台架试验结果、整车疲劳试验结果和底架仿真结果进行了对比分析。[结果及结论]该地铁车体整车底架和端部底架在单向疲劳损伤和组合载荷疲劳损伤的情况下,均没有产生裂纹的风险,满足标准相关要求。此外,将载荷放大后端部底架在疲劳试验时可以获得更为保守的结果,并且端部底架有限元模型的仿真结果和试验结果一致性较好,可以真实反映整车模型的应力状态,满足相关标准的要求。

[Objective]The car body of metro vehicle is a welded structure,and its fatigue strength is obviously smaller than that of the base metal due to the influence of stress concentration,welding defects and welding residual stress.As the part connecting bogie and car body,the end underframe of metro vehicle bears more load.Therefore,it is necessary to study its fatigue life.[Method]The numerical simulation and fatigue test are jointly used to study the fatigue life of the end underframe of a certain type of metro train.Firstly,a finite element model of metro vehicle is established and the corresponding fatigue load and evaluation points are determined.Then,the fatigue damage simulation is carried out on the whole train and the end underframe respectively.Finally,the bench test on the end underframe is performed,and the result is compared with that of the train fatigue test and the simulation result of the end underframe.[Result&Conclusion]Under the condition of unidirectional fatigue damage and combined load fatigue damage,both the vehicle chassis(underframe)and the end underframe of the metro train car body have no risk of cracking,meeting the requirements of the relevant standards.Meanwhile,the end underframe can obtain more conservative results in fatigue test when the load is amplified,and the simulation results of the end underframe finite element model are in good agreement with its test results,which can truly reflect the stress state of the train model and meet the requirements of the relevant standards.