基于假设分布的重载货车关键结构剩余寿命预测方法

Residual Life Prediction Method for Key Structures of Heavy Haul Freight Cars Based on Hypothetical Distribution

针对状态修中的关键结构剩余寿命问题,提出基于假设分布的剩余寿命预测方法,并以车钩为例,对该方法进行验证。基于线路测试或动力学仿真,获取车钩载荷时间历程,并编制其疲劳台架试验载荷谱;开展台架试验,获取车钩退化数据;基于假设分布对裂纹尺寸数据进行拟合优度检验,确定良好假设分布类型,得到结构累积失效概率图;基于累积失效概率图,对车钩剩余寿命进行预测。对于无可用试验数据的情况,结合断裂力学理论,给出基于有限元法的结构裂纹扩展分析流程,并以车钩为对象,预测一定裂纹尺寸下的剩余服役寿命。研究结果表明,基于假设分布的钩体剩余寿命预测均值与实际剩余寿命趋势一致,随探伤里程的增大,预测精度逐渐提高,整体来看,平均相对误差为38.35%,在工程应用可接受范围之内;基于数值仿真预测的钩体剩余服役寿命相对保守,可考虑结构不同部位多裂纹对系统可靠度的影响来提高预测精度。

Aiming at the problem of key structural residual life in condition-based repair,a residual life prediction method based on hypothetical distribution was proposed,which was verified by taking the coupler as an example.Firstly,the load-time history of the coupler was obtained based on the line test or dynamic simulation,and the load spectrum for its fatigue bench test was compiled.Secondly,the bench test was carried out to obtain the degradation data of the coupler.Then,based on the hypothesis distribution,the goodness of fit of crack size data was tested to determine the type of good hypothetical distribution,and to obtain the cumulative failure probability diagram of the structure.Finally,the residual life of the coupler was predicted through the cumulative failure probability diagram.In the case of no available test data,the analysis flow of structural crack propagation based on finite element method was described combined with the fracture mechanics theory.Taking the coupler as the object,the residual life under a certain crack size was predicted.The results show that the average of predicted residual life of the coupler based on hypothetical distribution is consistent with the trend of actual residual life.With the increase of crack detection mileage,the prediction accuracy increases gradually.On the whole,the average relative error is 38.35%,which is within the acceptable range of engineering application.The residual useful life of the coupler based on numerical simulation prediction is relatively conservative,and the influence of multiple cracks,located at different parts of the structure,on the reliability of the system can be considered to improve the prediction accuracy.