Research into the problem of wheel tread spalling caused by wheelset longitudinal vibration

This study mainly focuses on the mechanism of wheel tread spalling through wheelset longitudinal vibration that has been often neglected. Analysis of two actual cases of the wheel tread spalling problem leads to the conclusion that the wheel tread spalling is closely related to the wheelset longitudinal vibration in some locomotives, and many of these problems can be reasonably explained if the wheelset longitudinal vibration is considered. For better understanding of some abnormal wheel spalling problems, the formations of the wheelset longitudinal vibration and the wheel/rail contact parameters were analysed in the initial wheel tread spalling. With the preliminary analytical results, the wheelset longitudinal dynamic behaviour, the characteristics of wheel/rail contact and the mechanics in the condition of the wheelset longitudinal vibration were further studied quantitatively. The results showed that the wheelset longitudinal vibration changed not only the limit of these parameters and the position of principal stress, but also the direction of the principal stress on the surface of wheel/rail contact patch. It is likely that the significant stress changes provoke too much stress on the surface of wheel/rail contact patch, cause fatigue in wheel/rail contact patch and eventually lead to wheel tread spalling. The results of these studies suggest that the suppression of the wheelset longitudinal vibration extends wheel/rail life and the addition of a vertical damper with an ahead angle provides a possible solution to the wheel spalling problem.     

动车组不落轮镟床工序记录系统的设计

在动车组专项修中,处理CRH动车组轮对踏面擦伤与剥离的主要设备是动车组不落轮镟床,动车组不落轮镟床的正确操作关系着镟修作业的顺利完成.记录下操作人员每步操作,对严格落实设备操作规程,规范各项操作,实现标准化作业有着重要意义.本系统就是本着这一目的而设计,而且也为动车组镟修作业工序卡控的实现奠定了基础.     

侧风下高速列车车体与轮对的运行姿态

应用流体动力学理论,建立了高速列车空气动力学模型,计算了作用于高速列车车体上的气动力和气动力矩;应用多体动力学理论,建立了车辆系统动力学模型,分析了在不同风向角、侧偏角与合成风速下高速列车头车车体和轮对的运行姿态。计算结果表明:在不同侧风环境下,头车车体始终向背风侧横摆和侧滚;当风向角为90°时,车体的横向位移和侧滚角最大;当列车车速为350 km.h-1,侧风风速分别为13.8、32.6 m.s-1时,列车头车车体最大横向位移分别为74.2、171.7 mm,最大侧滚角分别为3.1°和8.4°;当列车车速为200 km.h-1,风速不小于32.6 m.s-1,且风向角为90°时,列车头车一、二位轮对均向背风侧横移,背风侧车轮易发生爬轨现象,三、四位轮对均向迎风侧横移,三位轮对迎风侧车轮易发生爬轨现象;四位轮对的横移量和摇头角均小于前三位轮对,相对安全。     

驱动工况单轮对横向稳定性

为了解驱动工况下轮对横向稳定性,建立了考虑驱动力矩的简化单轮对动力学模型,针对不同轮轨的黏着特性,研究了弹性定位单轮的横向蛇行稳定性.结果表明:驱动工况下,轮对横向稳定性优于惰行工况,对于弹性定位动力单轮对,当平均蠕滑率为0.8%时,横向非线性临界速度为惰行时的1.1倍;驱动时,轮轨黏着饱和导致轮对摇头力矩减小,有利于横向稳定性,但纵向切向力增加使得横向切向力减小,对轮对横向稳定性不利.     

Dynamic responses of a high-speed railway car due to wheel polygonalisation

The polygonal wear around the wheel circumference could pose highly adverse influences on the wheel/rail interactions and thereby the performance of the vehicle system. In this study, the effects of wheel polygonalisation on the dynamic responses of a high-speed rail vehicle are investigated through development and simulations of a comprehensive coupled vehicle/track dynamic model. The model integrates flexible slab track, wheelsets and axle boxes subsystem models so as to account for elastic deformations caused by impact loads induced by the wheel polygonalisation. A field-test programme was undertaken to acquire the polygonal wear profile and axle box acceleration response of a high-speed train, and the data are used to demonstrate the validity of the coupled vehicle/track system model. Subsequently, the effects of wheel polygonalisation are evaluated in terms of wheel/rail impact forces, axle box vertical acceleration and dynamic stress developed in the axle considering different amplitudes and harmonic orders of the polygonal wear. The results suggest that the high-order wheel polygonalisation can give rise to high-frequency impact loads at the wheel/rail interface, and excite some of the vibration modes of the wheelset and the axle box leading to high-magnitude axle box acceleration and dynamic stress in the wheelset axle.     

轮径差对行车安全性的影响

分析了具有轮径差转向架的运动状态,建立了车辆动力学模型,以某高速车辆在直线上运行为例,采用德国低干扰谱,选择车辆运行速度为300 km·h-1,研究了轮径差对行车安全性的影响趋势,对比了转向架前后轮对同相轮径差与反相轮径差的影响程度。分析结果表明:所有的轮径差都会影响行车安全性,随着轮径差的增大,车辆运行安全性指标逐渐变差,反相轮径差对行车安全性影响较大,同相轮径差的影响较小。由此可知,在实际检修中应尽量减小轮对的轮径差,尤其应严格控制转向架前后轮对反相轮径差到允许范围之内,以保证车辆系统的行车安全性。     

改进Canny算子的列车轮对踏面边缘检测算法

现有对高速列车轮对踏面损伤检测逐步以动态检测系统代替人工检测,针对动态检测系统中对踏面损伤图像处理时,存在大量边缘信息丢失、图像细节不完整等问题,提出一种基于改进Canny算子的边缘检测算法.该算法利用自适应双边滤波代替传统高斯滤波对图像进行平滑处理,能够很好的保持图像边缘和滤除噪声;采用水平、垂直、45°和135°4...     

铁路货车轮对在线综合检测系统研究

针对重载铁路车辆轮对磨耗随重载和提速的发展日趋严重问题,提出构建铁路货车轮对在线综合检测系统.系统能够在线自动检测车辆的轮对尺寸和踏面擦伤,获得轮对尺寸参数及踏面擦伤和图像预警信息.对系统组成和功能、综合检测算法及环境适应性等方面进行分析,加入仿射算法补偿检测精度,通过磨耗预测算法模型及数据融合判别算法研究,提升系统可...     

城轨轮对压装润滑介质工艺研究

针对城轨轮对压装过程中常见的吨位小、涨吨拉伤现象,通过分析润滑介质性质、展开交叉试验,研究出一套润滑介质的优化工艺,试验结果表明,该工艺可减少吨位小、涨吨拉伤发生率。     

现代有轨电车车辆独立轮对与传统轮对曲线导向能力分界点计算

采用单轮对纯滚线判别法与整车动力学仿真方法,对现代有轨电车低地板列车采用的传统轮对与独立轮对的曲线导向性能分界点进行深入研究,为轮对选取与导向控制提供参考。从纯滚线角度分析,传统轮对曲线通过时趋向于纯滚线运动,独立轮对基本处于轮对最大横移位置,典型踏面下对应区域的线路曲线半径100~200 m为性能分界点。建立全传统轮对与全独立轮对的五模块现代有轨电车列车模型进行分析,典型踏面下各项指标结果同样表明两种轮对的性能分界点为线路曲线半径100~200 m区域。