关键词： 城市轨道交通   直线电机   轮轨关系   圆跳动   波磨  

摘要： 广州地铁5号线采用由直线电机驱动的列车,在运营中出现了较为严重的轨道波磨及车轮圆跳动,造成了车辆走行部的圆跳动发展迅速、电机高度调整装置失效、电机绝缘失效等一系列问题,经过诸如转向架轮轴改造、小曲线段加装轨旁轮轨摩擦控制装置、有针对性的轨道打磨等系统性的整治,轮轨病害初步缓解。

关键词： 重载铁路   交叉渡线   动力响应   轨底坡  

摘要： 30 t轴重重载道岔已在山西中南部通道正线上投入使用,但对配套重载交叉渡线的研究尚属空白。基于车辆-道岔耦合动力学,采用多体动力学分析软件SIMPACK建立30 t重载货车-12号交叉渡线动力仿真模型,分析重载列车过岔方式、过岔速度及轨底坡设计对行车安全性的影响,为30 t轴重重载铁路交叉渡线的设计提供合理建议。

关键词： 坡道   黏着系数   轮轨   防冻液   水介质  

摘要： 利用JD-1轮轨模拟试验机,通过设计坡道试验夹具实现了不同坡道接触条件的轮轨模拟试验,研究了第三介质条件下坡度对轮轨界面黏着特性的影响规律.结果表明:在干态、水介质和防冻液介质条件下,上下坡道工况的轮轨黏着系数均低于平直轨道工况;随坡道坡度的增加,黏着系数呈下降趋势且下坡道的黏着系数下降更为明显;与水介质相比较,轮轨界面存在防冻液时更容易引起低黏着现象;上坡道工况下,随速度和轴重的增加轮轨界面黏着系数呈略微下降的趋势.

关键词： 丛式井   轮轨式   钻机平移   顶升系统   平移系统  

摘要： 针对轮轨式钻机平移系统需要在低温、沼泽、沙漠等恶劣环境下进行丛式井钻井作业的特点,综合考虑经济、平稳、快速、安全可靠等因素,研发设计了新型轮轨式钻机平移及底座顶升系统。新型轮轨式钻机平移系统结构清晰,操作简单可靠,具有良好的经济性、可靠性、通用性和安全性。其中,顶升油缸的设计中,底座的支撑结构更简洁,底座调平和起放操作更方便。

关键词： 调车场   减速器   护轮轨   安装  

摘要： 由于初始设计漏项或施工原因,在驼峰调车场减速器区段,存在未安装专业护轮轨的情况,使车辆溜放过程中存在一定的安全隐患。在对具体事故调查的基础上,对驼峰调车场减速器区段进行现场勘查,明确护轮轨安装的原因,提出具体的安装条件、方案及养护工作建议。

关键词： AASHTO T 324   Hamburg Wheel-Track testing   Moisture sensitivity   Micromechanics finite element   Three-Stage Weibull   Asphalt   Pavement  

摘要： The Hamburg Wheel-Track Device (HWTD) test has recently gained popularity among many state highway departments of transportation (DOTs) for use in hot mix asphalt (HMA) moisture sensitivity evaluation. In this paper, suggestions are presented to improve and provide more consistent and representative results for this test as described in AASHTO T 324 - Hamburg Wheel-Track Testing of Compacted Hot Mix Asphalt (HMA). In the AASHTO T 324 specification, either a cylindrical or a slab specimen can be tested. Use of a two-dimensional micromechanics finite element (2D-MMFE) analysis has demonstrated significant gap/bonding and specimen shape effects on HWTD test results for the cylindrical specimen setup. In addition, the analysis suggests the best method for defining the "rut depth" to ensure consistent results between two specimen setups. Results of this study have concluded that: (1) slab specimens can provide more reliable test results due to larger size and uniform geometry;(2) two cylindrical specimens (cores) should be glued together to prevent localized failure due to larger peak maximum principal strains when there is no bonding;(3) measurements of average rut depth should be collected from stations near the centers of cylindrical specimens to keep the specimen shape effects to the lowest possible level;and, (4) an agency should not allow both specimen setups to be used interchangeably in the HWTD specifications. The investigation also suggests that the average rut depth evolution curve fitted using a three-stage Weibull approach can define the number of passes to failure and define the stripping initiation point (SIP) better than the visually determined SIP. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： 轮轨   激光改性   损伤   铁道车辆  

摘要： 总结了轮轨材料损伤的特点,介绍了轮轨材料激光改性技术的处理工艺和各种改性层的组织特征及性能的研究现状,分析了轮轨材料激光改性处理的发展趋势,并提出了今后的研究方向。

关键词： 重载铁路   轮轨接触   热效应   温升   相变  

摘要： 轮轨接触热损伤是重载铁路轮轨结构的主要失效形式之一。当重载列车机车加速牵引时,轮轨接触界面间发生相对滑动,轮轨相对滑动会导致轮轨接触区出现较高的接触温升,这种接触温升积累到车轮和钢轨材料的相变时会发生相变,从而导致轮轨接触表面的擦伤、裂纹和剥离等。本文将钢轨看作是弹性半空间体。首先利用轮对切片投影法计算轮轨接触几何关系,然后利用接触弹性方法计算了轮轨接触斑和法向接触应力,最后将得到的轮轨法向接触应力施加到钢轨弹性半空间模型中,利用Matlab软件编制了轮轨接触热效应分析程序,计算分析了轮轨接触的热效应,并研究了钢轨材料马氏体层产生的厚度、位置及其分布。针对不同的轮对横移量、车轮移动速度、摩擦因数和相对滑动速度进行了钢轨的温度场研究。结果表明:轮轨滑动接触热效应剧烈,温升可以达到奥氏体化临界点,形成脆硬的马氏体。计算结果也表明,利用弹性半空间假设研究轮轨接触热效应问题是可行的。

关键词： (lateral and vertical) Track irregularity   Finite element modeling   Hertz contact theory   Parametrization  

摘要： Track irregularity is an inevitable problem in any rail network and it is the source of track deterioration and degradation. This becomes evident in railway projects spanning cities. Hence, the effect of track irregularities on wheel-rai| contact relationship is studied with the aim to solve the contact geometry and contact pressure problems induced by these track irregularities. In this regard, independent analysis and parametrization of the rail head surface geometry and the wheel thread geometry is conducted first and the wheel and rail contact point is determined, with the help of the predefined simplified coordinate system. After the identification of the wheel-rai| contact point, mathematically, Hertzian contact theory is applied to calculate the contact area. Accordingly, for an applied normal wheel load of 125kN, the contact area was found to be 118.3 mm? Finite element models were also used to simulate the lateral and vertical irregularities, with the help of computer software, ABAQUS. Eight finite element models were analyzed for the study: four for lateral irregularity, three for vertical irregularity, and one model for the tracks without irregularity. When lateral irregularity is applied on the model the contact pressure on the rail was found to be increasing as compared to the model simulating tracks without irregularity, with a maximum increment of 33.34% for +30mm lateral irregularity. However, contact area and normal contact force induced on the rail decreases by 15.47%, for -8mm and +10mm lateral irregularity, and 15.17%, for +20mm lateral irregularity, respectively. Similarly, for the applied +30mm vertical irregularity the contact pressure increases by 54.14%, however for +10mm vertical irregularity the contact pressure decreases by 9.15%. Moreover, the +30mm vertical irregularity gives the maximum contact area with a magnitude of 67.66 mm.

关键词： 高速车轮   轮轨接触   空洞   应力应变   有限元法  

摘要： 针对高速车辆车轮材料的空洞现象,利用弹塑性有限元方法,建立了车轮材料含有空洞的轮轨接触三维数值模型。模型中采用了非线性的车轮材料本构关系,计算分析了空洞大小、位置和轮重对车轮材料应力应变分布的影响。计算结果表明:轮轨接触作用下,空洞附近车轮材料易出现塑性变形和应力集中现象,且在160°和340°的空洞附近应力和应变值最大;在小于1 mm范围,空洞直径为0.1 mm时车轮材料最易萌生裂纹;当空洞离踏面距离小于15 mm,空洞离踏面距离对车轮疲劳萌生影响明显;随着轮重增加,其空洞附近车轮材料应力应变会随着增大。