基于动应力的地铁构架疲劳损伤与疲劳寿命计算

Calcultion for Fatigue Damage and Fatigue Life of Metro Bogie Based on Dynamic Stress

作为轨道车辆走行部的极关键结构,转向架构架的服役安全性受到极大重视与关注。以新设计的地铁车辆动车转向架样本构架为研究对象,基于其在位使用状态下的动应力进行疲劳损伤与疲劳寿命研究。结合车辆运行状态数据,研究构架关键部位的损伤分布特征,分析构架疲劳损伤快速累积的原因。针对样本构架关键部位:计算其裂纹萌生寿命;基于雨流计数后的应力幅子样完成应力幅分布核密度估计;建立裂纹扩展模型,采用蒙特卡洛法与反函数法计算构架关键部位不同运行里程下的累积失效概率。结果表明,构架累积失效概率随运行里程增加而快速增加,裂纹萌生后对应于97.5%可靠度的运营里程为3万km;构架疲劳寿命为裂纹萌生寿命与扩展寿命之和,97.5%可靠度下为48.39万km。研究结果为进一步提升构架抗疲劳设计、优化转向架检修周期提供研究基础。

As the key structure of the running gear of rail vehicles, the service safety of bogie frame has received great attention.Therefore, the newly designed bogie frame sample of metro vehicle is taken as the research object, and the fatigue damage and fatigue life are studied based on its dynamic stress in service. Combined with the vehicle running state data, the damage distribution characteristics of the bogie’s key parts are studied, the reasons for the rapid accumulation of fatigue damage are also analyzed. For the key parts of the bogie frame sample: the crack initiation life is calculated;the kernel density of stress amplitude distribution is estimated, which is based on the stress amplitude samples after rain flow counting;the crack propagation model is established;and by the use of Monte Carlo method and inverse function method, the cumulative failure probability under different operating mileage is calculated. The results show that the cumulative failure probability of the bogie frame increases rapidly with the increase of operating mileage, and the operating mileage corresponding to 97.5% reliability is 30,000 km after crack initiation;the fatigue life of the frame is the sum of crack initiation life and propagation life, and it is 483 900 km under 97.5% reliability. The research results provide a research basis for further improving the anti fatigue performance of the frame and optimizing the maintenance cycle of the bogie.(1)