实测工况下快速地铁车辆一系弹簧疲劳寿命分析

Fatigue life of primary steel circular springs of fast metro vehicles under the measured working conditions

针对一系钢圆弹簧的疲劳失效问题,文中以某城市地铁一系钢圆弹簧内簧为研究对象,首先,对内簧有限元模型进行静强度分析,结果表明:有限元分析结论与理论解相对误差不超过1.0%;其次,建立快速地铁动力学模型,以14 km实测轨道波磨数据为激励,仿真得到不同车轮状态-轨道激励匹配下的内簧振动位移-时间历程,运用雨流计数法将其转化为8级疲劳载荷谱;结合线性Miner疲劳损伤理论,预测出内簧的疲劳寿命。以AW3+工况为例,实测轨道谱-多边形轮状态下,内簧疲劳寿命为10万km,符合其实际运行寿命。研究结果表明:弹簧所受载荷工况、车轮及轨道状态、簧丝直径都是影响一系钢圆弹簧疲劳寿命的因素,对比分析不同工况下内簧的疲劳寿命值,在弹簧所受载荷工况和车轮状态相同时,实测轨道激励下内簧的最短疲劳寿命比新轨激励下的要短得多;当内簧处于实测轨道谱下,AW0工况下多边形轮的疲劳寿命值为新轮下的1/3;在车轮和轨道条件相同时,AW3+工况下疲劳寿命值为AW0工况下的1/385;最后,提出定期钢轨打磨、提高弹簧刚性和限制超载量等一系列减少一系钢圆弹簧内簧疲劳断裂的有效措施。

This article,aimed at fatigue failure of primary steel circular springs,focuses on the inner spring of the primary steel circular springs of the metro vehicle in a city.Firstly,the inner spring's finite-element model is subject to the analysis on static strength;the results show that the error between the solution obtained from the finite-element analysis and the theoretical solution is smaller than 1.0%.Secondly,the dynamics model of the fast metro vehicle is set up;the 14-kilometer track corrugation data is used as the excitation,and the time period of the inner spring's vibration displacement load with the mataching of different wheel conditions-track excitation is worked out by means of simulation;the rain-flow counting method is applied to transform it into an eight-level fatigue load spectrum;in combination with the linear Miner fatigue-damage theory,the fatigue life of the inner spring is predicted.With the AW3+working condition as an example,the fatigue life of the inner spring is 100,000 kilometers under the measured track spectrum-in the state of polygon wheel,which is in line with its actual service life.The results show that the load exerted on the spring,the wheel and track conditions,and the the spring wire's diameter have influence on the fatigue life of the primary steel circular springs.The comparative analysis is conducted on the fatigue life of the inner spring under different working conditions.When the load and wheel conditions are same,the minimum fatigue life of the inner spring with the measured track excitation is much smaller than that with the new track excitation;when the inner spring is under the measured track spectrum,the fatigue life of the polygon wheel under the AW0 working condition is 1/3 of that of the new wheel.When the wheel and track conditions are same,the fatigue life under the AW3+working condition is 1/385 of that under the AW0 working condition.Finally,a lot of effective measures to reduce the fatigue fracture of the inner spring of the primary steel circular springs are proposed,such as regular rail grinding,improved spring rigidity,and limitation of overload.