中图分类号：U270 DOI：10.3969/j.issn.1004-132X.2025.04.021

Fatigue Failure Study and Topology Optimization of Metro Vehicle Cowcatchers Based on Virtual Excitation Method

LIU Yang1 WEN Zefeng1*WU Xingwen² ZHOU Yabo1 TAO Gongquan1 ZHANG Zhenxian³HOU Jianwen³ YI Zhi4 1.State Key Laboratory of Rail Transit Vehicle System，Southwest Jiaotong University， Chengdu，610031 2.College of Mechanical Engineering，Southwest Jiaotong University，Chengdu，610031 3.CRRC Qingdao Sifang Locomotive amp; Rolling Stock Co.，Ltd.，Qingdao，Shandong，266041 4.Chengdu Metro Operating Co.，Ltd.，Chengdu，610036

Abstract： The cowcatchers were an important safety guarantee device for metro vehicles. The causes of the cowcatcher failure were investigated by field test and theoretical research.The results indicate that the resonance of the cowcatcher contributes to the premature fatigue failure due to the first-order eigenmode frequency （95.7Hz） ） which is close to the passing frequency 95Hz ）ofthe rail corrugation in smal-radius curves. Topology optimization design of the cowcatchers was carried out according to the causes of failure based on the mistuning modal design method.The first-order eigenmode frequency was raised to 160Hz ，and the resonance problems of the cowcatchers were solved.A sub-structure analysis technique was proposed based on the virtual excitation method.A random vibration model was established to reproduce the vibration environment of the cowcatchers under real conditions. And the dynamic stresses at key positions was calculated and the results show that the maximum dynamic stress error between simulation and measurement as 1.8% . Finally，the excitation loading method was optimized，and the fatigue life of the cowcatchers was verified based on field test data.The fatigue life of the optimized cowcatchers was calculated by using the Dirlik and the ZhaoBaker method，and the results show that the optimized structure meets the design life requirements of 30 years and 3.6 million kilometers at both of the weld and base material locations.

Key words： cowcatcher; rail corrugation; dynamic stress; virtual excitation; fatigue life

0 引言

排障器是轨道车辆中广泛使用的安全装置，其作用是清除轨道上的障碍物。当列车在线路上运行时，任何障碍物都可能影响列车运行安全，甚至造成脱轨等严重后果。因此，排障器在保障车辆运行安全性、可靠性等方面发挥着极其重要的作用。对于地铁车辆，排障器通常安装于头尾车转向架构架的前方，并设计为悬臂式焊接结构。由于其特殊的结构和工作方式，经常发生疲劳失效。

对于排障器的强度仿真，已有学者开展相应研究。童小山等基于EN15227标准对电力机车排障器进行了静强度分析，并通过实验验证了排障器的静态安全性。付耿哲[2]对高速碰撞条件下排障器的结构强度进行了仿真研究，验证了排障器的碰撞安全性。郑雨豪等[3仿真分析了地铁车辆排障器焊缝位置的疲劳强度，并指出了排障器发生失效的原因。张明等[4]针对地铁车辆轮缘润滑装置吊架断裂问题，采用动应力试验与有限元仿真相结合的方法确定了吊架断裂成因，并基于仿真分析验证了优化结构的合理性。此外，也有学者针对排障器的结构优化进行了研究。李永华等[5]以损失模型为理论基础，利用信噪比方差得到排障器型材板厚的最佳参数组合，并进行抽样模拟计算，得到稳健优化后的动车组排障器结构。谭惠日等6基于变密度法对内燃机车排障器进行结构拓扑优化设计，应用尺寸优化设计方法对排障器结构进行轻量化设计，使优化后结构最大应力幅值降低 20% ，质量减小 9.29% 。……