机车轮箍崩裂原因分析

机车轮箍在运行中发生崩裂。为确定轮箍失效原因,采用断口观察、低倍检验、力学性能检测和化学成分分析等方法对失效轮箍进行分析。结果表明,轮箍崩裂由轮缘处热裂纹引起,热裂纹的产生与其使用、路况等因素有关。     

模糊模式识别在轮箍超声横波探伤中的应用

轮箍是铁路机车运行的重要部件,在制造和使用过程中出现的各种危害性缺陷会严重威胁到列车的行驶安全.用超声无损检测缺陷,回波的识别易受轮箍标记、闸瓦、轮轨接触点及表面波等多种因素的干扰.在超声横波探伤基础上,可将模糊模式识别应用到机车轮箍的无损检测中.以内燃机车轮箍为实验检测对象,使用了多个标准人工伤模拟轮箍自然缺陷.通过提取缺陷回波频域相关特征建立典型缺陷的模糊子集,并运用基于贴近度的择近原则对未知缺陷进行分类识别.实验结果证明了该方法有效.对同一缺陷重复检测的正确识别率达92.5%.     

DK-1型电空制动机典型故障的原因分析和对策

SS4改型电力机车作为重联补机(附挂)使用时,DK-1型电空制动机有时会发生制动缸不缓解的故障,致使闸瓦与轮箍长时间摩擦运行,造成机车轮箍发热弛缓,严重影响行车安全,针对一起典型故障,通过多次现场模拟试验和分析,提出防治措施。     

准高速内燃机车车轮热应力分析

在轴对称模型基础上,本文运用ANSYS软件分别模拟计算了内燃机车轮箍式车轮组装应力,列车制动时因摩擦热而引起的应力,并模拟计算在不同过盈量组合下轮箍式车轮因过盈装配而引起的组装应力和列车制动时引起的热应力,并得出相应的结论,为确定车轮过盈量、组装工艺,了解机车运用中轮对工作状况提供了依据。     

对轮箍落锤试验的分析

分析了轮箍落锤试验并结合实际检测结果，论述了轮箍落锤试验的目的和意义，在此基础上，提出对目前轮箍落锤试验的意见。     

火车轮箍裂纹成因分析

采用低倍检验、金相检验及化学成分分析等方法对火车轮箍机加工出现裂纹的原因进行了分析。结果表明：轮箍裂纹是由于钢锭中存在严重的皮下气泡，在轮箍热加工过程中皮下气泡处金属被氧化烧穿导致不能粘合而形成裂纹。     

JK00430型机车走行部车载在线监测装置的应用体会

介绍了JK00430型机车走行部车载在线监测装置的基本构成和在机车运用过程中取得的效果,并对该装置的使用情况进行了客观评价。     

智能压力检测系统测量精度设计与分析

在对机车制动系统的压力信息在线监测必要性后，根据机车运行过程中制动系统在各工况下的实际工作情况。从理论上计算分析了压力检测系统必需达到的检测精度，以理论计算结果作为设计依据，对压力检测系统各环节的误差进行计算与分配，并根据计算结果对压力检测系统中各构成环节进行参数设计和元器件选择。实验结果表明根据各环节误差分析结果设计的系统的检测精度达到了设计要求。     

接触网-受电弓振动主动控制问题的研究

针对铁路机车受电引系统存在的振动问题，提出了一种基于模糊技术的旨在抑制振动的主动控制方案。在对接触网－受电弓系统特征进行了基础上，设计开发了以PⅡ300工控机为主控器件的受电弓主动模糊空制系统，并以SS7型机车受电弓为对象进行了试验，试验结果表明，采用主动控制技术以后，受电弓弓头接触压力波动值大大降低，弓网系统者到了明显改善。     

发电厂电气设备在线监测装置信息管理研究

本文通过对发电厂中装设的电气设备在线监测装置的研究，结合现场设备投运情况，探讨在目前条件下，发电厂在线监测装置信息管理方案，提出在发电厂设计过程中对在线监测装置进行系统设计，建立信息管理系统的观点。     

车轮多边形态下机车轮轨动态响应研究

某和谐型电力机车车轮运营中表现出较为严重的多边形磨耗,对机车的零部件失效、乘坐舒适性和运行安全性产生较大影响。为研究车轮多边形态下机车轮轨动态响应规律,基于SIMPACK软件建立了考虑机车牵引行为和轮对、钢轨等部件柔性的刚柔耦合动力学模型,利用机车振动试验结果对模型进行验证。研究了典型车轮多边形阶次、幅值和运行速度等对轮轨力和振动响应的影响,并分析了机车牵引行为对轮轨蠕滑率/力和车轮磨耗的影响。结果表明,速度等级为70 km/h时,车轮18阶多边形态下激发了轮对一阶弯曲共振,出现了轮轨力波动大和机车异常振动的现象;机车牵引状态下显著增大了纵向蠕滑率的波动幅值,并提高了纵向蠕滑力,导致轮轨磨耗指数相比无牵引工况下大幅增加,加剧车轮多边形磨耗的发展。     

考虑轨道弹性时机车轮对的纵向振动研究

在电机轴悬式机车-轨道垂向耦合动力学模型的基础上,考虑了机车的纵向运动自由度,通过对比牵引工况下考虑和不考虑轨道弹性时的轮轨作用力及轮对振动加速度,得到了轨道弹性变形对轮对轮轨切向力及其纵向振动的影响规律。研究结果表明,当轮轨界面无不平顺激扰时,考虑或忽略轨道结构的弹性对轮对牵引力的发挥及纵向振动影响不大;在不平顺激扰下,轨道结构参与轮轨间的耦合振动,由于轨道垂向的弹性及阻尼作用,轮轨垂向力特别是高频力得到缓冲及衰减,致使50Hz以上高频段的轮轨切向力及轮对纵向振动变的缓和,利于轮周牵引力的稳定发挥。总体上,分析模型中若不考虑轨道弹性会造成预测的轮轨切向力及轮对振动加速度偏大。     

轮对径向质心偏离对纵向振动的影响

当轮对质心存在径向偏离时,会引发周期性粘着系数的变化,与剧烈的自激扭转振动,从而直接导致轮对产生纵向振动。轮对纵向振动与轮轨黏-滑振动相互耦合,破坏了机车稳定动力学性能。通过某新型机车的建模和数值仿真,计算和分析在不同的质心偏离和速度下,构架、轮对的纵向振动频率与车体垂向共振频率。并计算轮对粘着系数变化规律,分析机车垂向平稳性恶化的机理。结果表明当轮对存在径向偏心时,轮轨蠕滑力饱和产生动力学耦合,引起轮对的扭转振动和纵向振动,由此将通过构架与牵引装置的传递而恶化机车垂向平稳性。     

Limitations and potential improvement of the aircraft pavement strength rating system to protect airport asphalt surfaces

A pavement strength rating system is internationally adopted in order to protect aircraft pavements from inadvertent overload. The system has two elements. The primary element is designed to protect the pavement against subgrade rutting and the second is intended to protect asphalt pavement surfaces. The surface-protection element is arbitrary and empirical, placing category-based limits on aircraft tyre pressures. In 2008, increases in the tyre pressure limits were proposed by aircraft manufacturers and these were approved in 2013. The research reported in this paper assesses the impact of tyre pressure and individual wheel load increases on calculated flexible pavement stress indicators, as well as identifying an improved surface layer protection element. Stresses were calculated near the surface, at the surface layer interface and at the subgrade. Tyre pressure and wheel load combinations included current (18 t and 1.35 MPa), imminent (33 t and 1.75 MPa) and future (40 t and 2.15 MPa) aircraft. Surface layer stress increased significantly (20–30%) with increases in both tyre pressure and wheel load. The subgrade stress increased near-equally (97%) with wheel load but was insensitive (<1%) to tyre pressure changes. The ability of the current aircraft pavement strength rating system to protect pavements from the increasing demands of aircraft was demonstrated to be limited to the subgrade. It is recommended that the tyre pressure rating be amended to reflect the combined impact of both tyre pressure rating and individual wheel load. It is also recommended that ongoing efforts to incorporate additional asphalt surface failure modes into routine pavement design be given high priority. The importance of these issues is reinforced by the limited availability of remedies to counter any negative impacts of increased surface layer stresses, especially in hot climates.     

机车牵引销冲击动力学特性分析

基于车辆/轨道耦合动力学理论,分析对比了选用两种方案转向架情况下机车动力学特性,以及对牵引销结构冲击的影响。以某型米轨机车为例,结合国外山区线路特征,使用动力学软件SIMPACK构建车轨耦合动力学模型。通过模拟实际线路工况分析发现直线工况下由于牵引销纵向自由间隙的存在,在较差线路上高速运行时,由于轨道纵向激励的影响使得牵引销受到较大的纵向冲击,原始方案三个牵引销按顺序最大纵向力分别为165kN、197kN和167kN;改进后方案的牵引销纵向力最大值为165kN、141kN和186kN。小半径曲线工况下原始方案牵引销与横向止档发生剧烈碰撞,第二位牵引销所受的横向冲击最大,达到259kN,而考虑车轮磨耗时,冲击将达到785kN。改进方案牵引销横向冲击较小,均未超过45kN。结果表明：通过小半径曲线时,牵引销产生的巨大横向力可能是造成牵引销固定螺栓松动、剪断的原因。在较差线路上,轨道不平顺造成的纵向冲击这也可能引起该问题。     

The steady-state cornering of a wheel with a reinforced tyre with slipping

We investigate the steady-state cornering of a wheel with a deformable periphery on the plane with slipping. A previously proposed analytical model of a reinforced tyre is considered. The surface of the tyre is represented by flexible tread, combined with parts of two tori (sidewalls of the tyre). The contact between the wheel and the plane occurs by the part of the tread. The force interaction between the tyre and the plane is represented by a model of dry friction assuming that the pressure of flexible tread on the plane is constant in the contact area. For this steady-state regime of rolling in a circle with breakaway and camber of the wheel and slipping in the contact area, all the parameters determining the form of the deformed tyre, the contact area and its location, as well as the relations between the external forces and moments, required for the realisation of this regime are found.     

交-直-交型电力机车网侧谐波对牵引变电所的影响及改进

本文分别对比介绍了新型交-直-交型大功率电力机车和以SS4为代表的传统型交-直型电力机车的主电路拓扑结构及其网侧电流谐波特性。由测试结果表明大功率电力机车与传统电力机车相比最显著的特征是其谐波特性不同,并分析了网侧谐波对牵引变电所电气设备造成的影响和采取的相应的技术改进措施,确保牵引供电系统的正常运行。     

Fracture in a rubber-sprung railway wheel

In the year 1998 near Eschede the German ICE-high speed train Wilhelm-Conrad Röntgen got into an accident on its way from Munich to Hamburg with catastrophic results. The broken wheel tyre of the rubber-sprung wheel finally was identified as reason for the accident. The following paper deals with numerical stress analyses as well as with fracture mechanical evaluations for this ICE-wheel tyre fracture.     

Reliability Analysis for Degradation of Locomotive Wheels using Parametric Bayesian Approach

This paper undertakes a reliability study using a Bayesian survival analysis framework to explore the impact of a locomotive wheel's installed position on its service lifetime and to predict its reliability characteristics. The Bayesian Exponential Regression Model, Bayesian Weibull Regression Model and Bayesian Log‐normal Regression Model are used to analyze the lifetime of locomotive wheels using degradation data and taking into account the position of the wheel. This position is described by three different discrete covariates: the bogie, the axle and the side of the locomotive where the wheel is mounted. The goal is to determine reliability, failure distribution and optimal maintenance strategies for the wheel. The results show that: (i) under specified assumptions and a given topography, the position of the locomotive wheel could influence its reliability and lifetime; (ii) the Bayesian Log‐normal Regression Model is a useful tool. Copyright © 2013 John Wiley & Sons, Ltd.     

机械弹性车轮径向刚度特性及影响因素研究

为解决充气轮胎爆胎的问题,提高车辆防刺破及越野路面的行驶性能,对非充气结构机械弹性车轮径向刚度特性及影响因素进行研究。建立了机械弹性车轮非线性有限元模型,并通过负荷特性试验验证了模型的有效性;分析了使用条件和车轮结构等因素对机械弹性车轮径向刚度的影响,揭示了地面约束、材料、垂直载荷及力矩对车轮固有频率和振型的影响规律,为机械弹性车轮结构及整车动力学特性优化提供了参考。