基于Bootstrap法的轨道车辆镁合金主S-N曲线研究  

Simulation and Verification of Main S-N Curve of Magnesium Alloy for Railway Vehicles Based on Bootstrap Method

作　　者：杨建业 张哲 董祺 白智文 Yang Jianye;Zhang Zhe;Dong Qi;Bai Zhiwen(Key Laboratory of Railway Industry on Safety Service Key Technologies for High-speed Train,Dalian Jiaotong University,Liaoning,Dalian 116028,China)

机构地区：[1]大连交通大学高速列车服役安全关键技术铁路行业重点实验室,辽宁大连1160280

出　　处：《铁道技术标准（中英文）》2023年第9期8-15,32,共9页Railway Technical Standard(Chinese & English)

摘　　要：在轨道车辆轻量化设计中采用镁合金可以达到显著减少车体质量、提高列车运行速度以及减轻运营能源消耗的优化目标。针对在小子样疲劳试验空间中,镁合金焊接结构各存活率下主S-N曲线获取较为困难的问题,首先提出结合Bootstrap自助法与等效结构应力法的疲劳评估方法。在此框架下,对不同板厚、材料、类型和应力比的镁合金焊接接头进行物理疲劳试验,并采用有限元仿真,进行试件接头焊趾处的等效结构应力数值模拟试验。其次,分别采用传统成组法和Bootstrap自助法拟合得出不同存活率下镁合金焊接结构疲劳寿命预测模型的统计参数。结果表明,Bootstrap自助法得到的镁合金疲劳试验样本拟合结果更趋于稳定,提高了镁合金疲劳寿命试验数据的拟合程度和样本数目较小时疲劳寿命预测的准确性。基于此方法得到并验证了镁合金焊接结构主S-N曲线的较精确回归模型。The use of magnesium alloy in the lightweight construction of rail vehicles can achieve a significant reduction in body mass and improve train operating speed and reduce operating energy consumption.It is difficult to obtain the master S-N curve for each survival rate of the magnesium alloy welded structure in the small specimen fatigue test space.To solve this problem,first,a fatigue evaluation method combining bootstrap self-help method and equivalent structural stress method is proposed.In this framework,physical fatigue tests are performed on magnesium alloy welded joints with different plate thicknesses,materials,types and stress ratios,and numerical simulations of equivalent structural stresses at the weld toe of the specimen joints are performed using finite element simulation.Secondly.Secondly Grubbs criterion is used after correcting the data combined with the ASME standard specification of curve fitting,respectively using the traditional grouping method and bootstrap method of fitting the statistical parameters of the fatigue life prediction model of magnesium alloy welded structures with different survival rates.The result show that the magnesium alloy fatigue test sample fitting results obtained by the bootstrap method are more stable and improve the degree of fitting of magnesium alloy fatigue test data and the accuracy of fatigue life prediction when the size of samples is small.Based on this method,a more accurate regression model of the master S-N curve of the magnesium alloy welded structure was obtained and validated.

关 键 词：轨道车辆 镁合金焊接疲劳 Bootstrap自助法 主S-N曲线 

分 类 号：U270.12[机械工程—车辆工程]