钢轨磨损特性试验研究及分级使用建议

由于重载铁路与高速铁路的损伤形式不同,分别表现为磨损与疲劳两种形式,故钢轨选材的技术要求也是不相同的.针对我国目前使用的钢轨材料,通过大型模拟试验,系统研究在不同钢轨材料在不同线路环境上的伤损情况及规律,通过全面考虑钢轨磨损与疲劳裂纹之间的平衡, 确定不同线路运输条件下的最佳钢轨材料,建立钢轨的分级使用制度,达到从源头上防治钢轨伤损的目的,指导我国铁路钢轨材料的选用.     

[表面强化及损伤机理]钢轨打磨机理研究进展及展望

综述了钢轨打磨过程中材料的去除机理,主要包括钢轨打磨时材料的去除模型、钢轨打磨温度场,并在此基础上介绍了不同打磨参数、打磨磨石与打磨工况下钢轨材料的去除行为,提出了钢轨打磨效率和打磨质量相互作用机制,总结了钢轨打磨对轮轨滚动接触疲劳的影响因素。提出了未来重点研究方向建议：开展针对磨石特性（如磨料成分、结合剂、粒度、硬度、气孔等）的研究,研发适合我国钢轨的打磨磨石,以提高打磨作业效率和质量,降低打磨作业成本;进一步开展其他特殊工况下的钢轨打磨试验;将钢轨打磨与其他铁路维护作业相结合,在保证轮轨接触状态良好的条件下延长钢轨使用寿命。     

铁路钢轨缺陷伤损巡检与监测技术综述

我国高速铁路的快速发展给铁路钢轨基础设施的状态维护和安全保障带来挑战,综述了钢轨不同类型缺陷伤损的巡检与监测技术。回顾总结了国内外钢轨无损检测与监测技术的特点和局限性,以及钢轨在线巡检与监测仪器的应用情况。分析了多模态多物理集成传感与可视化成像检测、宏观与微观组织状态观测、无损检测与评估和健康监测集成融合,以及基于大数据管理的铁路钢轨快速巡检和实时监测等新技术研究进展,讨论了未来铁路钢轨缺陷伤损巡检及监测技术的发展趋势。     

钢轨打磨机理研究进展及展望

综述了钢轨打磨过程中材料的去除机理,主要包括钢轨打磨时材料的去除模型、钢轨打磨温度场,并在此基础上介绍了不同打磨参数、打磨磨石与打磨工况下钢轨材料的去除行为,提出了钢轨打磨效率和打磨质量相互作用机制,总结了钢轨打磨对轮轨滚动接触疲劳的影响因素。提出了未来重点研究方向建议:开展针对磨石特性(如磨料成分、结合剂、粒度、硬度、气孔等)的研究,研发适合我国钢轨的打磨磨石,以提高打磨作业效率和质量,降低打磨作业成本;进一步开展其他特殊工况下的钢轨打磨试验;将钢轨打磨与其他铁路维护作业相结合,在保证轮轨接触状态良好的条件下延长钢轨使用寿命。     

钢轨养护及一种钢轨轮廓检测方法

钢轨是铁路运行的基础设施,钢轨廓形的变化直接影响轮轨接触情况,从而影响列车运行的平稳和舒适度,影响钢轨及轮对的磨耗情况及使用寿命。因此,它对铁路运行有着十分重要的作用。本文将重点介绍钢轨养护,同时阐述一种钢轨轮廓检测方法。     

基于钢轨型面扩展法的车轮型面设计

首先对欧洲国际铁路联盟(Union enternationale des chemins der fer, UIC)高速轮轨型面S1002/UIC60和我国准高速型面LMa/CHN60进行接触几何分析,认为LMa/CHN60型面共形度太低,对钢轨磨损以及滚动接触疲劳极为不利.以改善钢轨的受力状态为出发点,在对钢轨型面扩展法进行数值研究的基础上,采用钢轨局部型面扩展法,根据我国60 kg/m钢轨设计出共形度较高的车轮型面.通过车辆轨道耦合动力学仿真确定车辆临界速度约为400 km/h,且具有较好的曲线通过性能.轮轨非赫兹滚动接触分析表明,在靠近钢轨一侧接触斑面积、应力等较LMa型面变化不大的情况下,离开钢轨一侧接触斑面积明显增大,接触应力降低约20%,钢轨与车轮的接触带变宽,钢轨接触频次得到改善.在车轮型面优化设计做了尝试性工作,以期为我国高速、重载以及城市轨道交通车辆车轮型面优化设计提供借鉴.     

钢轨滚动接触疲劳研究

介绍了滚动接触疲劳裂纹的萌生及扩展的形成机理、钢轨滚动接触疲劳的破坏分类、影响因素,从钢轨新材料的开发、轮轨接触几何型面的优化和铁路工况的改善等几个方面提出了减缓钢轨滚动接触疲劳的措施。     

基于储能的移动式钢轨闪光焊机供电系统优化设计

铁路是世界上最重要的载客交通工具之一，而无缝铁路的轨道焊接是轨道安全运行的关键技术之一。传统的移动式钢轨闪光焊机因其柴油发电机组怠速运转和三相负荷严重不平衡会产生大量燃油消耗问题。针对这一问题，研究了一种新能源移动式钢轨闪光焊机。该设备在传统移动式钢轨闪光焊机的基础上，优化发电机组功率，通过使用储能单元及高功率逆变器设计一种“增程式”的供电系统。首先针对钢轨闪光焊机的供电系统进行原理阐述，确定设计的基本原理和使用设备的基本参数。接着对其电源质量、焊接接头质量以及经济性进行实验分析。实验结果表明，此次设计的新能源移动式钢轨闪光焊机极大地减少了能源的消耗，电源质量和焊接接头质量优秀。     

钢轨廓形测量自动对齐技术研究

随着我国铁路发展的高速化，铁路钢轨的形态直接影响列车的运行安全，钢轨廓形是表征钢轨服役形态的重要特征，分析钢轨廓形与基准廓形的偏差是钢轨精细化维护的重要问题，分析钢轨廓形与基准廓形的偏差的基础是廓形对齐，因此，高精度的对齐方法是亟待解决的问题。本文阐述了基于相关性以及DTW（动态时间调整）2种方法实现廓形自动对齐。经过实践表明，本文所述的2种方法能有效提升廓形对齐精度。     

PD3与U71Mn钢轨材料微观与宏观磨损性能分析

采用纳米压痕划痕仪与AFM,研究PD3与U71Mn钢轨微观力学性能与摩擦磨损特性,通过拉伸实验和JD-1轮轨模拟试验机研究2种钢轨的宏观力学特性与摩擦磨损性能。结果表明:2种材料力学性能在微观和宏观表现一致,即PD3钢轨硬度较大、抗压能力强,具有良好的抗磨损能力;U71Mn钢轨塑性高、韧性大,具有良好的抵抗疲劳的能力。微观实验结果显示,2种钢轨在载荷不大时都以磨粒磨损为主,随载荷增大,交变应力作用增强,受疲劳影响PD3钢轨划痕两侧出现沟纹;U71Mn划痕损伤在犁沟摩擦力作用下,产生塑性变形。微观与宏观实验结果具有一致性,对2种钢轨磨损特性的测量误差在5%之内,因此在一定程度上可以用微观实验来代替宏观实验研究钢轨材料的摩擦磨损特性。     

Ultrasonic Multichannel Flaw Detector for Testing Rails with Signal Recording

Although automated testing instruments have been introduced intensely on the railways of Russia, up to 95% of hazardous flaws in rails are detected by ultrasonic two-line (removable) flaw detectors. The paper describes the functional diagram and basic functions of an ultrasonic detector of the new generation, AVIKON-01, with continuous recording of data. The instrument is supplied with the software package for analysis of testing results, and it has advantages of both hand-held removable flaw detectors and high-performance instruments for nondestructive testing of rails.     

Real-time monitoring of railroad track tension using a fiber Bragg grating-based strain sensor

Railway and train security are very important in preventing service disruption and ensuring quality and safe journeys. Conventional gauges are used in laboratory environments for the strain measurement of rails used in railways. However, the use of these electrical sensors is not practical in long-distance railways. Instead, access to long distances is possible with fiber optic sensors. In this study, the strain of 49E1 type rail with R260 hardness and quality was calculated theoretically. These results were compared with an experimentally established fiber Bragg grating system. Moreover, a user-friendly interface was prepared for real-time monitoring of the system. Upon examining the results, the maximum deviation at a rate of 2.5% occurred in the strain measurement in the rail in response to force changes between 0 and 200 kN. A value of approximately 1.38?pm/µε was calculated between the wavelength/strain changes.     

[表面强化及损伤机理]钢轨表面宽带激光淬火工艺及其疲劳磨损性能

针对目前钢轨强化采用的欠速淬火方法存在强化层硬度偏低、耐磨性难以满足重载线路使用要求的问题,使用3种不同光斑宽度的激光,研究了U71Mn材质钢轨的激光淬火强化工艺,获得了不同扫描速度下的临界功率和淬火层深,并测试了淬火层在滚动接触条件下的磨损与接触疲劳性能。结果表明：在临界熔化的激光能量密度下,光斑宽度由6 mm增加到20 mm时,淬火层深度提高了38%,或在获得相同的淬火层深度情况下,处理效率提高6.8倍;淬火层组织为针状马氏体,硬度从原来的300HV提高到800HV以上;20万周次的磨损试验后,激光淬火试样的磨损量只有未处理试样磨损量的25%,未处理试样以表面接触疲劳剥落和塑性变形为主,激光淬火试样仅有轻微的疲劳磨损,耐磨性和抗接触疲劳性能优异。     

[制造与维修工艺]高速铁路无砟轨道系统状态监测及预防性维修

高速铁路无砟轨道系统直接承载高速列车的高频冲击和振动,钢轨伸缩变形等状态变化都会严重影响列车安全,传统周期性检修易出现过修或失修问题,针对此,利用光纤光栅传感技术建立高铁无砟轨道系统状态监测平台,提出监测内容和监测点布置方案。通过对监测数据基本特征的分析,并结合轨道质量指数,建立了无砟轨道状态BP神经网络预测模型,预测了轨道服役状态。预测结果可指导铁路运营维护部门及时、合理地进行轨道养护维修,实现高铁轨道系统的预防性维修。     

双PSD实现长直导轨四自由度测量的新方法

介绍一种基于双二维PSD实现大长度宽范围直线导轨俯仰角、偏摆角以及空间二维直线度等四个自由度在线测量的新型方法,对其测量原理进行了分析和论证,并建立了求取长直导轨俯仰角、偏摆角的数学模型和基于激光空间偏角修正基础上的二维直线度的数学模型;讨论了影响测量过程的各种因素,提出了消除其影响所应采取的措施。该测量方法提高了长直导轨直线度的测量精度和效率。     

滚子夹套式回转支承轮压均衡方法研究

针对大型回转式起重机械采用滚子夹套式回转支承存在的轮压分布不均衡问题,提出了改变回转支承上轨道不平度的解决方案,探讨了应用有限元分析软件模拟调整轨道不平度实现轮压均衡的具体方法,并设计了验证性试验对实物模型进行了现场测试。试验结果表明,通过调整回转支承上轨道不平度可以改善轮压分布,证明以文中提出的有限元方法指导调整回转支承上轨道不平度可行。     

Multi-point contact of the high-speed vehicle-turnout system dynamics

The wheel-rail contact problems, such as the number, location and the track of contact patches, are very important for optimizing the spatial structure of the rails and lowering the vehicle-turnout system dynamics. However, the above problems are not well solved currently because of having the difficulties in how to determine the multi-contact, to preciously present the changeable profiles of the rails and to establish an accurate spatial turnout system dynamics model. Based on a high-speed vehicle-turnout coupled model in which the track is modeled as flexible with rails and sleepers represented by beams, the line tracing extreme point method is introduced to investigate the wheel-rail multiple contact conditions and the key sections of the blade rail, longer nose rail, shorter rail in the switch and nose rail area are discretized to represent the varying profiles of rails in the turnout. The dynamic interaction between the vehicle and turnout is simulated for cases of the vehicle divergently passing the turnout and the multi-point contact is obtained. The tracks of the contact patches on the top of the rails are presented and the wheel-rail impact forces are offered in comparison with the contact patches transference on the rails. The numerical simulation results indicate that the length of two-point contact occurrence of a worn wheel profile and rails is longer than that of the new wheel profile and rails; The two-point contact definitely occurs in the switch and crossing area. Generally, three-point contact doesn’t occur for the new rail profile, which is testified by the wheel-rails interpolation distance and the first order derivative function of the tracing line extreme points. The presented research is not only helpful to optimize the structure of the turnout, but also useful to lower the dynamics of the high speed vehicle-turnout system.     

On the Question of Monitoring Residual Stresses in Selectively Heat-Strengthened Rails

The question is considered of the relationship between the divergence of a longitudinal (400 mm) groove in the rail web, used as an indirect residual-stress–based rejection criterion, with internal stresses measured by acoustic strain gaging across the rail section. The internal stresses have also been evaluated in individual rail elements after cutting. A finite element simulation in the COMSOL Multiphysics software environment has been performed in order to establish connection between groove divergence and stresses. Results are presented for experimental measurements over 49 sections of different rails. The relationship is demonstrated between the stress level in rail elements and the level of stresses measured by an electromagnetic-acoustic structuroscope in an experiment on the side of the railhead. Based on the modeling and experimental results, an acoustoelastic technique is proposed for monitoring residual stresses in rails as an expert method with a rejection level of 80 MPa when sounding a rail section on the side of its head.     

The Structure and the Magnetic and Mechanical Properties of Steel M74 and the Possibility of Nondestructive Testing of Heat-Treatment-Hardened Rails

Dependences of the coercive force, the relaxation magnetization, the hardness, and the strength and plastic properties of steel M74, intended for manufacturing railroad rails, on its tempering temperature were studied. Hardened specimens have the martensite structure as well as the sorbite structure of different dispersity. Analogous dependences of critical fields, which correspond to the displacement of 180° and 90° domain walls during the magnetization reversal, and of the induced magnetic-anisotropy field were also analyzed. An MC-ИФМ magnetic structure analyzer was shown to be suitable for the nondestructive testing of the mechanical properties of finished rails. The correlation model is two-parameter; i.e., analyzer readings are used that were recorded after successive magnetization reversals of inspected sections of rails to magnetic fields corresponding to two different currents in the electromagnetic coils.     

双PSD实现长直导轨四自由度测量的新方法

介绍基于双PSD实现大长度宽范围直线导轨俯仰角、偏摆角以及空间二维直线度等四个自由度在线测量的新型方法,对其测量原理进行了分析和验证,并建立求取长直导轨俯仰角、偏摆角的数学模型和基于激光空间偏角修正基础上的二维直线度的数学模型;讨论影响测量过程的各种因素,提出消除其影响所应采取的措施。