机车车体枕梁关键含缺陷结构疲劳寿命评估  

Fatigue life assessment of key defective structures of locomotive body sleeper beam

作　　者：范晓达 朱涛[1] 张弛[1] 王超[1] 肖守讷[1] 阳光武[1] FAN Xiaoda;ZHU Tao;ZHANG Chi;WANG Chao;XIAO Shoune;YANG Guangwu(State Key Laboratory of Rail Transit Vehicle System,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学轨道交通运载系统全国重点实验室,四川成都610031

出　　处：《中南大学学报（自然科学版）》2024年第4期1644-1653,共10页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(52175123);四川省杰出青年基金资助项目(2022JDJQ0025);四川省国际科技创新合作项目(2022YFH0075)。

摘　　要：为研究枕梁含缺陷结构服役安全问题,首先,基于有限元仿真对比不同尺寸下的底架枕梁结构刚度、挠度,根据最佳结构试验尺寸开展等效疲劳台架试验,获取焊缝关注点的应力分布状态及潜在裂纹位置,并验证枕梁结构与仿真模型的一致性;然后,基于BS 7910:2019标准中结构完整性评估方法,通过引入当量化裂纹缺陷获得结构临界失效状态,实现关键焊缝区域的寿命预测,同时结合断裂力学数值仿真方法,从仿真角度实现局部模型结构的裂纹扩展模拟,对含裂纹缺陷结构的损伤容限进行分析;最后,对比分析基于标准评估的理论方法与数值仿真方法结果的可靠性和差异性。研究结果表明:枕梁子模型结构台架试验与仿真模型的应力分布具有较好的一致性,枕梁结构薄弱区域集中在垂向减振器角焊缝位置,基于BS 7910:2019标准和数值仿真计算得到的减振器座角焊缝表面缺陷临界深度分别为6.50 mm和7.85 mm,对应疲劳载荷循环数分别为1.029×105和1.121×105次,两者评估结果具有较好的一致性。In order to study the service safety of structures of sleeper beam with defects,firstly,the structural stiffness and deflection characteristics of the sleeper beam in bottom under different sizes were compared based on finite element simulation.According to the optimal structural test size,the equivalent fatigue bench test was carried out to obtain the stress distribution state and the potential crack position of the weld focus,and the consistency between the structure of sleeper beam and the simulation model was verified.Then,based on the structural integrity assessment method in BS 7910:2019 standard,the critical failure state of the structure was obtained by introducing the quantified crack defect,and the life prediction of the key weld area was realized.Combined with the numerical simulation method of fracture mechanics,the crack growth simulation of the local model structure was realized from the perspective of simulation,and the damage tolerance analysis of the structure with crack defects was completed.Finally,the reliability and difference of the results of the theoretical method based on standard evaluation and the numerical simulation method were compared and analyzed.The results show that the stress distribution of the submodel structure bench test of sleeper beam is consistent with that of the simulation model.The weak area of the submodel is concentrated in the fillet weld of the vertical shock absorber.Based on the BS 7910:2019 standard and numerical simulation calculations,the critical depths of the surface defects of the fillet weld of the shock absorber seat are 6.50 mm and 7.85 mm,respectively,and the corresponding fatigue load cycles are 1.029×105 and 1.121×105.The results of the two evaluations are in good agreement.

关 键 词：机车车体 焊接结构缺陷 FAD图 疲劳寿命评估 应力强度因子 

分 类 号：U260.2[机械工程—车辆工程]