地铁车辆转向架吊耳的失效分析及寿命预测

Failure Analysis and Life Prediction of Bogie Lifting Lugs for Metro Vehicles

针对某型地铁车辆在运行过程中转向架吊耳发生失效断裂问题,通过光学和电子显微镜分析失效吊耳的断口形貌,得出吊耳发生疲劳断裂的结论。为研究吊耳发生共振疲劳的机理和评估方法,在该型地铁车辆运营线路上对尚未发生断裂的吊耳进行了动应力和振动加速度测试。经对吊耳和轴箱的振动加速度进行时域及频域分析,研究其频谱特征,证明轮轨发生波磨的激振频率与吊耳的一阶固有频率相同;结合吊耳的受力情况,对其动应力结果进行分析,用Miner线性累计损伤法评估其寿命,证明吊耳在共振疲劳的条件下寿命严重不足。据此总结出吊耳在受到轴端振动激励条件下的共振疲劳寿命评估方法。接着对结构和材料改进后的新型吊耳采用共振疲劳寿命评估方法进行了寿命预测,对比分析了不同结构和不同材料的新型吊耳在运营条件下的频谱特征和剩余寿命,可为设计人员开发出满足地铁车辆使用寿命要求的新型吊耳提供依据。

In view of the failure and fracture of the bogie lifting lug of a certain type of metro vehicle during operation,the fracture morphology of the failed lifting lug is analyzed by optical and electron microscopes,and the conclusion is drawn that fatigue fracture of the lifting lugs occurred.In order to study the mechanism and evaluation method of resonant fatigue of the lifting lug,the dynamic stress and vibration acceleration tests are conducted on the lifting lugs that have not yet fractured on the operating lines of this type of metro vehicles.By analyzing the vibration acceleration of lifting lug and axle box in time domain and frequency domain and studying the frequency spectrum characteristics,it is proved that the excitation frequency of wheel-rail corrugation is the same as the first-order natural frequency of lifting lug;Combined with the stress of the lifting lug,the dynamic stress results are analyzed,and the life of the lifting lug is evaluated by Miner linear cumulative damage method.It is proved that the service life of lifting lugs under the condition of resonance fatigue is seriously insufficient.Based on this,the resonant fatigue life evaluation method of lifting lug under the condition of shaft end vibration excitation is summarized.Then,the life of the new type of lifting lug with improved structure and material is predicted by resonance fatigue life assessment method,and the spectrum characteristics and remaining service life of the new type of lifting lug with different structure and different materials under operating conditions are compared and analyzed,which can provide a basis for designers to develop new type of lifting lug that meets the service life requirements of metro vehicles.