摘要
针对设计标准规定的设计载荷不能真实反映地铁车辆焊接构架实际服役条件,以及大量随车实测数据信息在构架结构设计方面挖掘不充分的问题,基于线路实测的地铁车辆构架薄弱位置处的应力-时间历程样本信息,提出一种抗疲劳设计谱编制方法。首先,采用雨流计数法编制反映构架损伤的实测应力谱,根据疲劳损伤理论确定应力-次数-损伤关系;然后,采用贝叶斯参数估计与核密度估计得到应力外推结果,以有序样本聚类确定小应力门槛值;最后,考虑焊接部位截面突变引起的应力集中,采用热点应力法和应力线性化方法得到应力集中系数,对实测应力谱进行修正,实现设计谱的编制。研究结果表明,根据应力极值外推和归一化的应力-次数-损伤关系分析,确定小应力门槛值为3.18 MPa,相比于由传统方法确定的应力门槛值结果偏大8.19%,小应力循环次数舍弃效果显著;在确保构架满足现役条件的情况下,考虑载荷分散性和焊缝处应力集中系数,确定了设计里程与等效应力的关系,进一步说明设计谱编制的必要性。研究结果为实现构架设计载荷谱编制方法构建和结构等强度设计奠定基础。
In view of the problem that the formulary design load based on the design standard cant truly reflect the actual service conditions of the welded frames of subway vehicles,and a large number of online measured data information has not been fully explored in the structural design of the frame,an anti-fatigue design spectrum compilation method based on the stress-time history sample information measured at the weak position of the subway vehicle frame was proposed.The small stress threshold value was determined by clustering ordered samples using the rain-flow counting method to compile measured stress spectrum reflecting structural damage,determining the stress-frequency-damage relation based on the fatigue damage theory,and using the methods of Bayesian parameter estimation and kernel density estimation to obtain stress extrapolation results.Considering the stress concentration caused by structural geometry changes in the cross-section of the welding site,the hot spot stress method and stress linearization method were used to obtain the stress concentration coefficient,and the measured stress spectrum was corrected to achieve the compilation of the design load spectrum.The research results show that the small stress threshold value is 3.18 MPa determined by extrapolation of stress extremes and the relation analysis between normalized stress-frequency-damage,which is 8.19%higher than the stress threshold value determined by traditional methods,the effect of discarding the number of small stress cycles is significant.Considering the load dispersion and stress concentration factor at the weld seam,while ensuring that the structure meets the current service conditions,the relation between the design mileage and equivalent stress is determined,the necessity of compiling the design spectrum is emphasized further.The above research builds the construction method of load spectrum compilation and the equal strength design of structures.
作者
薛海
田爱琴
马龙
张羽帆
XUE Hai;TIAN Aiqin;MA Long;ZHANG Yufan(CRRC Qingdao Sifang Co.,Ltd.,Qingdao 266111,China;School of Mechanical Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China)
出处
《机械强度》
北大核心
2025年第10期114-123,共10页
Journal of Mechanical Strength
基金
甘肃省教育厅高校教师创新基金项目(2023A-043)
甘肃省自然科学基金项目(23JRRA909)。
关键词
构架
应力谱
损伤等效
应力集中
设计谱
Frame
Stress spectrum
Damage equivalence
Stress concentration
Design spectrum
