高速列车转向架构架结构的疲劳可靠性模型

摘要

为了准确评估高速列车转向架构架的疲劳可靠性,通过转向架构架相同材料焊缝结构的多级小样本疲劳试验数据,得到指定寿命下疲劳强度分布的概率密度函数;采用双参数雨流计数法,根据实测构架结构的复杂随机应力 时间历程曲线编制构架的应力谱,再按照Miner准则和疲劳损伤等效原则计算对应的恒幅对称循环等效应力,并由此拟合得到高速列车服役寿命下等效应力分布的概率密度函数;根据得到的构架疲劳强度分布函数和等效应力分布函数,以等效应力小于疲劳强度为疲劳破坏判据,建立高速列车转向架构架的等效应力—疲劳强度可靠性模型.以某型高速列车转向架构架横侧梁连接处为对象,基于焊接结构疲劳试验和长期跟踪测试试验数据,对模型进行验证.结果表明:模型可用于评估构架的疲劳可靠性,可为焊接构架结构的进一步优化及全寿命周期管理提供依据;该型高速列车转向架的构架结构在1 200万km总运行里程的服役寿命下,其可靠度达99.36％,安全系数较高.%In order to assess accurately the fatigue reliability of high-speed train bogie frame,the probability density function of the fatigue strength distribution under specified life was obtained through the multistage and small sample fatigue test data of the same material weld structure of bogie frame.With double parameter rain-flow counting method,the stress spectra were compiled according to the measured complex random stress-time history curve of frame structure.The corresponding symmetrical cyclic equivalent stress with constant amplitude was calculated according to the Miner criterion and fatigue damage equivalent principle.And the probability density function of the equivalent stress distribution under the service life of high-speed train was obtained by fitting the equivalent stress.Then,according to the obtained fatigue strength and equivalent stress distribution functions,the equivalent stress-fatigue strength reliability model of the bogie frame for high-speed train was established with the equivalent stress less than the fatigue strength as the fatigue failure criterion.Based on the data of welded structure fatigue tests and longterm tracking tests,the model was verified by taking the transverse beam joint on the bogie frame of a high speed train for the object.Results show that the model can be used to assess the fatigue reliability of the frame,and provide the evidence for the further optimization and whole life cycle management of welded frame structure.The reliability of the bogie frame structure for this type of high speed train reaches 99.36％ and thus has a higher safety factor under the service life of 12 million km total running mileage.