铁路重载货车钩舌疲劳裂纹萌生寿命分析

ANALYSIS ON FATIGUE CRACK INITIATION LIFE OF COUPLER KNUCKLE OF RAILWAY HEAVY-HAUL WAGON

为更加精确掌握重载货车关键零部件的健康状态,结构在既有服役条件下的裂纹萌生寿命是研究重要环节之一。为精确分析重载货车钩舌的疲劳裂纹萌生寿命,提出了基于分离体模型的疲劳裂纹萌生寿命分析方式。首先,分别构建了基于应变测点的均布载荷模型、基于接触非线性的接触力模型,以及基于承载特性的载荷分布模型,三种不同承载状态下的钩舌裂纹萌生寿命模型;然后,对比分析了三种承载状态下钩舌有限元仿真与台架试验结果,证明基于应变测点的均布载荷模型的各测点弹性应变结果与台架试验测试结果吻合最好;最后,基于均布载荷模型,采用局部应力应变法,开展了重载货车钩舌疲劳裂纹萌生寿命分析,表明钩舌疲劳损伤危险部位为上下牵引凸缘根部,在特定的载荷谱条件、95%置信度,以及90%存活率下,其疲劳裂纹萌生寿命为1.22万公里。

In order to more accurately grasp the health status of key parts of heavy-haul wagon, the crack initiation life of the structure under existing service conditions is one of the important links of the research. In order to accurately analyze the fatigue crack initiation life of heavy-haul wagon coupler knuckle, an analysis manner of fatigue crack initiation life based on the separated body model is proposed. Firstly, the uniform load model based on strain test points, the contact force model based on contact nonlinearity, and the load distribution model based on load-bearing characteristics were constructed respectively, three types of knuckle crack initiation life models under different load conditions;Then, the finite element simulation under the three load-bearing conditions and bench test results of the knuckle are compared and analyzed, and it is proved that the elastic strain calculation results of each test point in the uniformly distributed load model based on strain test points are in good agreement with the results of bench test;Finally, based on the uniform load model and the local stress-strain method, the fatigue crack initiation life analysis of the heavy-haul wagon coupler knuckle is carried out. It shows that the dangerous part of the knuckle fatigue damage is the roots of the upper and lower traction flanges. Under specific load spectrum conditions, 95% confidence and 90% survival rate, its fatigue crack initiation life is 12 200 kilometers.