Research on Wheel Rail Wear for a 140 t Open Type Hot Metal Car

To maintain the safety of an open-type hot-metal car and to reduce wheel-rail wear during transportation, simulation models of the main components of such car were built using Pro/E software and then tested. In particular, the Pro/E models were imported into ADAMS/Rail for assembly and then used to construct a complete hot-metal car dynamic model. Locomotive wheel-rail attack angle, wheel-rail lateral force, and wear index were used as evaluation parameters during the simulation to analyze the effects of bogie parameter, rail parameter, and speed of the hot-metal car on wheel-rail wear. An improvement scheme for reducing wheel-rail wear was proposed based on the result of the dynamic simulation, wherein wheel-rail wear and curving performance were analyzed and compared. The simulation provided an important reference for evaluating and improving the dynamic performance of the hot-metal car. The applied effect showed that the improvement scheme is effective.

Research on rail wear of small radius curve in EMU depot

Purpose–With the help of multi-body dynamics software UM,the paper uses Kik–Piotrowski model to simulate wheel-rail contact and Archard wear model for rail wear.Design/methodology/approach–The CRH5 vehicle-track coupling dynamics model is constructed for the wear study of rails of small radius curves,namely 200 and 350 m in Guangzhou East EMU Depot and those 250 and 300 m radius in Taiyuan South EMU Depot.Findings–Results show that the rail wear at the straight-circle point,the curve center point and the circlestraight point follows the order of center point>the circle-straight point>the straight-circle point.The wear on rail of small radius curves intensifies with the rise of running speed,and the wearing trend tends to fasten as the curve radius declines.The maximum rail wear of the inner rail can reach 2.29 mm,while that of the outer rail,10.11 mm.Originality/value–With the increase of the train passing number,the wear range tends to expand.The rail wear decreases with the increase of the curve radius.The dynamic response of vehicle increases with the increase of rail wear,among which the derailment coefficient is affected the most.When the number of passing vehicles reaches 1 million,the derailment coefficient exceeds the limit value,which poses a risk of derailment.

Field investigation on effects of railway track geometric parameters on rail wear

Rail wear has dramatic impact on track performance, ride quality and maintenance costs. The amount of rail wear is influenced by various elements among which geometric parameters play an important role. The amount of wear in Iran’s railway lines and its imposed maintenance costs oblige us to make modifications on the various geometrical parameters. In order to ensure the effectiveness of these changes, it is necessary to investigate these parameters and their effects on the wear. This research is aimed at studying the effects of different track geometrical parameters on the vertical and lateral wear by conducting a three phase field investigation. The first phase was carried out at the switches of a station, the second phase at a straight line, and the third at a curved line out of the station. The results obtained are analyzed and the role of each track geometrical parameter in the rail wear is discussed. Recommendations for prevention or reduction of rail wear are presented.

Parameters studies for rail wear in high-speed railway turnouts by unreplicated saturated factorial design

Rail wear is one of the main reasons for reducing the service life of high-speed railway turnouts in China. The rail wear characteristics of high-speed railway turnouts are influenced by a large number of input parameters of the complex train-turnout system. To reproduce the actual operation conditions of railway turnouts, random distributions of these inputs need to be considered in rail wear simulation. For a given nominal layout of the high-speed railway turnout, 19 input parameters for rail wear simulation in high-speed railway turnouts are investigated based on orthogonal design of experiment. Three dynamic responses(wheel-rail friction work, normal contact force and size of contact patch) are defined as observed values and the significant factors(direction of passage, axle load, running speed, friction coefficient, and wheel and rail profiles) are determined by two unreplicated saturated factorial design methods, including the half-normal probability plot method and Dong 93 method. As part of the associated rail wear simulation, the influence of the wear models and the local elastic deformation on the rail wear was separately investigated. The calculation results for the wear models are quite different, especially for large creep mode. The local elastic deformation has a large effect on the sliding speed and rail wear and needs to be considered in the rail wear simulation.

Numerical simulation of wheel wear evolution for heavy haul railway

The prediction of the wheel wear is a fundamental problem in heavy haul railway. A numerical methodology is introduced to simulate the wheel wear evolution of heavy haul freight car. The methodology includes the spatial coupling dynamics of vehicle and track, the three-dimensional rolling contact analysis of wheel-rail, the Specht's material wear model, and the strategy for reproducing the actual operation conditions of railway. The freight vehicle is treated as a full 3D rigid multi-body model. Every component is built detailedly and various contact interactions between parts are accurately simulated, taking into account the real clearances. The wheel-rail rolling contact calculation is carried out based on Hertz's theory and Kalker's FASTSIM algorithm. The track model is built based on field measurements. The material loss due to wear is evaluated according to the Specht's model in which the wear coefficient varies with the wear intensity. In order to exactly reproduce the actual operating conditions of railway,dynamic simulations are performed separately for all possible track conditions and running velocities in each iterative step.Dimensionless weight coefficients are introduced that determine the ratios of different cases and are obtained through site survey. For the wheel profile updating, an adaptive step strategy based on the wear depth is introduced, which can effectively improve the reliability and stability of numerical calculation. At last, the wear evolution laws are studied by the numerical model for different wheels of heavy haul freight vehicle running in curves. The results show that the wear of the front wheelset is more serious than that of the rear wheelset for one bogie, and the difference is more obvious for the outer wheels. The wear of the outer wheels is severer than that of the inner wheels. The wear of outer wheels mainly distributes near the flange and the root; while the wear of inner wheels mainly distributes around the nominal rolling circle. For the outer wheel of front wheelset of each bogie, the development of wear is gradually concentrated on the flange and the developing speed increases continually with the increase of traveled distance.

Influence of Angle of Attack and Lateral Force between Wheel and Rail on Wear of Rail ——a Laboratory Study

Angle of attack and lateral force are two important parameters influencing wheel rail wear. This paper deals with the question of influences of the angle of attack and the lateral force on the wear of rail. A series of experiments are conducted on 1/4 JD 1 Wheel/Rail Tribology Simulation Facility. The angles of attack selected in the tests are 0°16′30″, 0°37′40″ and 1°0′0″ respectively. The lateral forces selected in the tests are 0.694 kN, 1.250 kN and 2.083 kN, respectively corresponding to the lateral forces of 25 kN, 45 kN and 75 kN measured in the field, with the aim of keeping the same ratio of L/V between laboratory and field conditions. It is found that the larger the angle of attack is, the more serious the wear of rail is. The relation of rail wear rate versus angle of attack is non linear, and the relation of rail wear rate versus lateral force is approximately linear. The influence of angle of attack is more serious than that of lateral force. For the tractive wheelset, the wear index involving linear and quadratic function terms of angle of attack has good agreement with the limited experimental data. Some conclusions are given.

轮轨摩擦系数对低地板轻轨动力响应及车轮磨耗的影响

为了确保低地板轻轨车辆安全且平稳地运行,以某轻轨线路为依托,利用多体动力学软件UM(Universal Mechanism)建立了低地板轻轨车辆-轨道耦合动力学模型。选用LM磨耗型车轮踏面以及R50标准钢轨,以美国六级不平顺轨道谱作为线路激扰。基于Hertz及Kalker简化理论、Archard模型,进行不同摩擦系数共5个工况下车辆动力响应以及车轮磨耗变化规律的仿真分析。在此基础上进一步分析了4个不同运行里程阶段对应共96组车轮磨耗型面下轻轨车辆安全性指标的变化规律。研究了4个不同运行里程阶段对应的不同车轮磨耗型面下车辆过曲线时安全性指标随摩擦系数的变化情况。结果表明:脱轨系数、轮轴横向力、轮轨横向力、车体横向加速度受摩擦系数的影响较为显著,而轮重减载率、车体垂向加速度对摩擦系数的改变并不敏感。车轮磨耗深度随里程和摩擦系数的增加而增大,且相同工况下独立旋转车轮的磨耗情况更加严重。在车辆运行40000 km后,其轮轨横向力、轮轴横向力、脱轨系数整体呈现随里程增加而增大的规律,而轮重减载率基本不受运行里程的影响。在不同摩擦系数及运行里程的叠加影响下,轮轨横向力、轮轴横向力、脱轨系数的峰值出现的位置不同,而轮重减载率却始终处于较为稳定的状态。

不同曲线半径下轨底坡与轮径差最佳匹配研究

为了研究不同曲线半径下地铁车辆动力学性能最优的轨底坡与轮径差最佳匹配,运用SIMPACK软件建立了地铁车辆动力学仿真模型,设置9种轨底坡工况和5种轮径差工况,以轮轨横向力、轮对横移量、脱轨系数、轮重减载率和轮轨磨耗指数作为车辆动力学性能的评价指标,以4种不同C型曲线半径作为研究对象,分析45种轨底坡和轮径差耦合工况下各指标的变化规律。采用熵权法对各指标进行加权求和处理,得到不同工况下的车辆动力学性能综合得分,最终分析得出车辆在不同半径曲线下轨底坡和轮径差的最佳匹配。研究结果表明:在300,400,500,600 m这4种曲线半径下,外轨轨底坡、内轨轨底坡和轮径差最优匹配方案分别为(1/20,1/40,+1),(1/20,1/40,+1),(1/30,1/30,-1),(1/40,1/30,-1)。

列车轮缘润滑材料性能分析与应用研究

通过基础摩擦磨损试验研究了干态摩擦和3种轮缘润滑棒条件下的轮箍材料试样的摩擦磨损行为,结合扫描电镜和表面测量仪观察磨损表面形貌、损伤特征和磨痕几何形状,对3种轮缘润滑棒进行能谱分析,探究了润滑成分对轮轨材料减摩的影响,并根据试验结果进行了2个月的现场机车轮缘磨耗跟踪测量.研究结果表明施加轮缘润滑棒作为润滑介质后可降低界面摩擦系数至0.15~0.50,试样表面摩擦损伤均有不同程度降低,3种轮缘润滑棒工况相比干态摩擦工况的试样磨损率分别降低17.21%、28.58%和20.50%;润滑剂成分研究表明,石墨-二硫化钼的轮缘润滑棒能在摩擦接触表面形成延展性强、覆盖率高的致密固体润滑膜,抗磨减摩性能最优;轮缘润滑棒B在DF12机车1轴轮对安装使用后轮缘磨耗有明显减缓,第1、4轴轮对轮缘磨耗之比下降50%.

载荷对D2车轮钢滑动磨损表层微观组织和性能影响

目的研究滑动磨损条件下,载荷变化对D2车轮钢表层微观组织和磨损性能的影响。方法利用MRH-30(环块)滑动摩擦磨损试验机进行滑动磨损试验。使用金相显微镜(OM)、场发射扫描电镜(SEM)、X射线衍射仪(XRD)和场发射透射电镜(TEM)等设备,分析滑动磨损后表层微观组织、表面磨损形貌和硬度变化。结果不同载荷条件下,随着磨损时间的增加,轮轨试样磨损量逐渐增加。200 N载荷条件下,(环状)车轮试样的磨损量大于100 N车轮试样磨损量,但200 N钢轨(块状)试样的磨损量却低于100 N钢轨试样。滑动磨损后,在不同载荷条件下,车轮试样表面主要形成长条状白层和不连续的月牙状白层。在200 N载荷条件下,由于车轮试样的磨损量较高,其白层厚度和表面白层硬度都小于100 N载荷条件下的车轮试样。在200 N载荷条件下,车轮试样表面更易形成不连续的月牙状白层。由于轮轨试样表面存在微凸体,高载荷会加速车轮试样表面局部微凸体发生严重塑性变形,导致月牙状白层的形成。在白层内片状渗碳体发生明显溶解和铁素体晶粒显著细化。结论车轮表面白层对磨损性能有明显影响。滑动磨损过程中,高载荷条件下,月牙状白层和周边微观组织界面易形成裂纹,裂纹会逐渐沿着界面向内部扩展,导致不连续月牙状白层发生剥落,降低车轮试样表面的硬度,加速车轮试样磨损。另一方面,高载荷会加速无白层区域塑性变形,导致其形成棘轮失效,从而加速磨损。

等效锥度非线性研究及其在踏面设计中的应用

为研究等效锥度非线性特性对车辆系统动力学和磨耗性能的影响,提出可以用于踏面优化设计的非线性特性建议指标。通过对轮轨关系进行细致推导,应用踏面逆向设计快速递推算法,得到具有不同等效锥度非线性特性的踏面,对不同踏面的轮轨关系进行分析。建立车辆系统动力学模型和基于Archard理论的磨耗预测模型,对不同非线性特性踏面的临界速度、横向平稳性、磨耗性能进行对比分析。研究结果表明:非线性因子值过高或过低都会导致临界速度下降,但该指标过高对临界速度影响更大,最大降幅可达20%;等效锥度非线性特性还会影响到踏面的磨耗发展,踏面的初始非线性因子越高,名义等效锥度在磨耗过程中的增长越慢,对延长车轮服役周期是有利的。综合动力学性能及磨耗性能,建议高速列车踏面的非线性因子应取尽可能接近于0的负值。在这一结论的指导下,对S1002CN踏面进行优化设计,得到名义等效锥度为0.1,等效锥度非线性因子为0.013(与S1002CN持平)、-0.002的优化踏面S1002CN_opt1、S1002CN_opt2,优化踏面S1002CN_opt2与S1002CN相比临界速度和横向平稳性有所优化,同时磨耗性能也有所提升。S1002CN_opt2与S1002CN_opt1之间的等效锥度非线性关系在动力学性能及磨耗性能中的表现证明以等效锥度非线性因子限值指导踏面进行优化设计的可行性,研究结果可为踏面设计及轮轨关系研究提供参考。

基于实测数据的车辆轮对磨耗模型研究

[目的]基于上海轨道交通17号线列车轮对实测数据,研究轮对磨耗规律,建立轮对轮缘厚度和轮径磨耗模型,以提高城市轨道交通车辆的安全性和维护效率。[方法]对轮对实测数据进行预处理,消除数据误差;采用曲线拟合和误差分析方法建立轮缘厚度和轮径的磨耗模型,并以磨耗速率拟合标准差,以及真实值与误差拟合曲线之间误差值的拟合标准差作为该模型的评价指标,评估轮缘厚度及轮径磨耗模型的准确性;分别针对1701次和1721次列车进行轮对磨耗模型验证。[结果及结论]1701次和1721次列车轮对轮缘厚度磨耗速率4次拟合曲线的拟合标准差,以及真实值与误差拟合曲线之间误差值的6次拟合曲线的拟合标准差均接近于零,验证了该车辆轮对磨耗模型的准确性,能够精确预测上海轨道交通17号线同一车型不同列车及同一列车不同位置的轮对磨耗情况。

现代有轨电车小曲线段钢轨磨耗特性分析

现代有轨电车线路条件受道路条件影响,小曲线路段较多,且交叉口平交段同社会车辆混行,因而轮轨磨耗现象严重。为了提升有轨电车钢轨寿命,减少运营阶段钢轨维修频率,通过现场调查、比较分析、仪器测试等手段,分析已运营有轨电车线路钢轨非正常磨耗的现状、分布规律以及典型磨耗区段的线路特征。实测过程中发现,部分轨道内外股钢轨踏面已偏离原始廓形,依靠外股的刚性导向作用,过大的横向作用力导致曲线外股侧磨严重。半径400 m以下的小曲线段钢轨主要磨耗类型为有规律的波浪形磨耗,属于典型的“响应型”波磨,符合有轨电车轻载运行的特点。

超高速滑动电接触CuCrZr合金轨道表面磨损机制及电接触性能

电磁轨道发射具有典型超高速滑动电接触特性(出口速度大于等于2000 m/s),电磁轨道表面会发生磨损。为研究轨道表面磨损状态与接触电阻之间关系,通过开展电磁轨道发射试验,研究发射后的CuCrZr轨道表面沉积层的形成与磨损机制,揭示枢轨间静态接触电阻的演变规律,总结沉积层的形成与接触电阻的关联关系。结果表明:沿着发射方向,轨道表面沉积层覆盖面积逐渐增大,沉积层的形成机制由摩擦材料转移变为电枢表面熔化飞溅,表面磨损特征由机械磨损向电气磨损转变;由于轨道不同位置沉积层形成原因不同,导致表面粗糙度分布不一致,枢轨间静态接触电阻随接触沉积层形貌特征改变呈现上升、下降及波动3个变化阶段;并且枢轨间静态接触电阻随着接触压力的增大而减小。研究成果对电磁轨道发射装备的研究及发射动力学研究具有理论价值。

基于轮轨非Hertz接触的货运铁路钢轨磨耗研究

随着铁路运营的发展,货车车辆轴重不断增加,钢轨磨耗异常严重。本文采用UM动力学软件,建立了三维铁路钢轨磨耗模型,计算了红柠铁路专用线部分线路条件下的钢轨磨耗情况。结果表明:(1)线路直线段内外钢轨的磨耗程度相近且较轻;(2)缓和曲线段内轨的磨耗集中分布在距离轮轨作用边轨头约10 mm的走行面处,而外轨磨耗集中分布在外轨内侧半径为80 mm的弧段曲线上;(3)圆曲线段外轨磨耗严重,主要分布在轨头内侧半径为80 mm的弧段上,半径为300 mm的弧段上也有明显磨耗;(4)内轨磨耗主要分布在轨头半径为300 mm的弧段上,半径为80 mm的弧段上磨耗较轻。

不同比例轮轨参数组合下钢轨磨耗演化及型面优化研究

文章研究实际小半径曲线上钢轨磨耗演化规律,设置车辆行驶速度、摩擦系数及车轮踏面类型按比例组合并分析对钢轨磨耗的影响。运用非均匀有理B样条曲线(Non Uniform Rational B-Spline,NURBS)构建钢轨参数化模型,并训练样本且基于神经网络(RBF)代理模型搭建以轮轨接触斑面积均方根ARMS和接触角差Δδ为目标函数的多目标优化模型。研究结果表明:左轨磨耗表现为侧磨,且磨耗量与通过总重线性相关;右轨磨耗表现为垂直磨耗,磨耗量也与通过重量呈线性相关;优化型面Opt1在接触斑面积均方根ARMS和接触角差Δδ两方面较原始型面均有所改善,且Opt1型面轮轨接触点分布更均匀,磨耗指数及动力学性能均有较好的改善。

低温环境下实验数据可视化的高铁制动摩擦虚拟仿真平台开发

随着计算机虚拟仿真技术的高速发展,虚拟仿真技术运用到高铁、交通、车辆等实验相关领域的需求日益增加。为解决高铁制动实验成本过高、实验安全及数据不具备可视性等问题,该文以Unity3D为开发平台,设计了一套不同环境温度下高铁制动盘摩擦磨损虚拟仿真实验平台。研究内容以SolidWorks、3dsMax等模型设计软件为基础搭建实验场景与机械结构,而Unity3D引擎用于UI设计并结合C#语言进行逻辑编写与功能实现,从而实现了一个高铁制动摩擦仿真实验数据可视化平台,使用户能够直观地分析不同环境条件下的制动盘磨损情况。

个性化设计廓形打磨钢轨在高速铁路小半径曲线波磨病害整治中的应用

我国某高速铁路半径为1 600 m曲线下股钢轨波磨病害严重,采用传统方式打磨后,波磨病害在4个月后再次产生。以现场实测钢轨廓形为基础,分别对该曲线上股、下股廓形进行个性化设计。采用个性化设计廓形打磨钢轨后,钢轨波磨产生周期延长至8个月。通过建立动力学模型和仿真计算,得出如下结论:较传统方式打磨,采用个性化设计廓形打磨钢轨,在轮对横移量为0~9 mm时的轮轨接触轮径差均得到不同程度增大;轮对横移量为6 mm时的轮轨接触锥度由0.087提升至0.133,提升了53%,车轮通过曲线能力明显增加;轮轨接触点均匀分布于轨面,在蛇行运动过程中,接触点在轨面均匀移动,跳跃少;曲线下股蠕滑率平均值的变化率下降89.6%,蠕滑率变化范围的变化率下降80.9%,轮轨运动更接近于纯滚动,轮轨接触状态更加稳定,对延长钢轨波磨病害产生周期有明显作用。

缩尺车轮-环轨滚动接触与磨耗特性仿真分析

为了研究缩尺车轮-环轨滚动接触与磨耗特性,基于轮轨滚动行为(WRRB)模拟试验台参数,利用ANSYS/LS-DYNA建立瞬态滚动接触有限元模型,集成弹性蠕滑率求解程序和Tγ磨耗模型,通过试验验证模型的正确性.重点分析轮轨力、蠕滑率、接触应力和钢轨磨耗深度,并考虑车轮驱动扭矩和速度的影响规律.结果表明:缩尺车轮-环轨结构的高频弹性振动造成轮轨垂向力波动;在比例载荷作用下,纵向动力学行为和钢轨磨耗深度变化趋势与服役轮轨一致;由于环轨的极小曲线半径,自由滚动工况下的横向蠕滑力/率、自旋蠕滑率、钢轨磨耗深度偏大,切向接触应力峰值出现在接触斑后沿两侧;车轮驱动扭矩和速度的影响规律可拟合为一组经验公式.研究可以为此类试验台的设计与应用工作提供理论依据.

基于微观蠕滑饱和的地铁线路钢轨波磨发生概率及发展特征

聚焦轮轨接触行为,从微观角度研究了地铁线路上钢轨波磨的发生概率和发展特性.利用车辆−轨道多体动力学数值模型,并结合Modified-Fastsim切向接触算法,提出了蠕滑率饱和临界值用于分析轨面光滑和粗糙条件下不同曲率半径线路上的波磨发生概率.同时,采用Archard模型计算了轮轨接触斑的平均磨耗深度,进而分析了钢轨波磨的演化特征.结果显示,内外侧轮轨接触蠕滑在线路曲线半径小于450 m时均趋近于饱和,说明内外侧钢轨均具有发生波磨的可能性,而当线路曲线半径大于450 m时,钢轨波磨发生概率降低.轨面不平顺的存在能够导致轮轨接触产生反馈振动,从而提高轮轨系统钢轨波磨的发生概率.随着线路曲线半径的增加,轮轨接触斑平均磨耗深度趋于减小,且平均磨耗深度减小速率表现为先增大后降低,说明曲线半径越小,钢轨波磨磨耗程度越大,磨耗速率越快.内外侧(左右侧)接触斑的平均磨耗深度变化相似,外侧接触斑的平均磨耗深度在小半径曲线上略高于内侧,表明内外侧(左右侧)钢轨的磨耗程度和磨耗速率基本相似,但考虑到内外侧轮轨接触几何关系有所差异,外轨倾向于轨侧波磨,内轨则主要为轨顶波磨.