车轮多边形对高速列车车轴疲劳强度影响研究

车轮多边形是铁道车辆一种常见的非圆化病害，对轮对振动和车辆运行安全有明显的影响。在建立刚柔耦合拖车和动车车辆系统动力学模型基础上，将车轮多边形简化为简谐波并将其考虑为车轮轮径的变化，研究20阶车轮多边形对拖车和动车车轴疲劳强度的影响。结果表明，等效应力幅比值与速度呈非线性关系，且拖车和动车峰值出现位置有所不同，拖车峰值位置出现在速度为225 km/h，对应多边形激励频率432.7 Hz；动车不同截面分别在300 km/h、375 km/h时存在峰值，对应多边形激励频率分别为576.5Hz、721.2Hz。在各峰值位置处，多边形幅值的变化对拖车和动车部分截面的等效应力幅比值均有显著影响。拖车和动车车轴等效应力最大值均位于C截面，并且随着车轮多边形幅值的增加，其等效应力显著增大，超过车轴疲劳强度限值，降低车轴使用寿命。研究结果有助于改善20阶车轮多边形对高速列车车轴疲劳强度及弹性振动的影响。

Study on the Influence of Wheel Polygon on the Fatigue Strength of High-speed Train Axle

Wheel polygon is a common defect of wheel irregularities of railway vehicles, which has significant influence on wheel set vibration and vehicle operation safety. Based on the establishment of rigid/flexible coupling trailer and motor vehicle system dynamics models, the wheel polygon is simplified into simple harmonics and considered as the change of wheel diameter. The influence of 20th order wheel polygon on the fatigue strength of the trailer axle and motor axle are studied. The results show that the equivalent stress amplitude ratio is in a non-linear relationship with the vehicle speed, and the peak positions of trailer car and motor car are different. The peak position of the trailer car occurs at the speed of 225 km/h, corresponding to the polygonal excitation frequency of 432.7 Hz, and the peak positions at 300 km/h and 375 km/h for different sections of motor car, and the corresponding polygonal excitation frequencies are 576.5 Hz and 721.2 Hz respectively. At each peak position, the change of the polygon amplitude has significant influence on the equivalent stress ratio of some sections of the trailer car and motor car. Both the maximum equivalent stress of trailer axle and motor axle lie in Section C, and with the increase of wheel polygon amplitude, the equivalent stress increases significantly, which exceeds the fatigue strength limit and reduces the service life of axle. It is useful of the results to improve the influence of 20th order wheel polygon on the fatigue strength and flexible vibration of high-speed train axle.