A contact-area model for rail-pads connections in 2-D simulations: sensitivity analysis of train-induced vibrations

A numerical model to predict train-induced vibrations is presented. The dynamic computation considers mutual interactions in vehicle/track coupled systems by means of a finite and discrete elements method. The rail defects and the case of out-of-round wheels are considered. The dynamic interaction between the wheel-sets and the rail is accomplished by using the non-linear Hertzian model with hysteresis damping. A sensitivity analysis is done to evaluate the variables affecting more the maintenance costs. The rail–sleeper contact is assumed extended to an area-defined contact zone, rather than a single-point assumption which fits better real case studies. Experimental validations show how prediction fits well experimental data.     

连续测力轮对的数字试验研究

利用现车辐板轮制作连续测力轮对是当今轮轨力测量的一个趋势。然而，在试验室完成测力轮对的贴片与标定是一件十分费事的工作，而且最佳的贴片位置也不容易找到。现提出以有限元为基础的计算机仿真方法，分别对在垂向、横向载荷作用下的车轮辐板上的应变分布进行计算，并和试验结果进行比较，计算机仿真结果和试验结果吻合较好，进而分析计算不同的垂向及横向加载点对车轮辐板观测点应变的影响，寻找最佳贴片位置。这种计算方法可以大大缩短测试轮对的设计及标定周期，寻找最佳贴片位置，提高轮轨力的测试精度。     

Tangential force variation due to the bogie direction reversal procedure

A range of tangential forces is generated within the contact patch when a wheelset moves on the rail. These forces are intensified when incorporating curved tracks and motored axle rail vehicles [Arrus, P., de Pater, A.D. and Meyers, P., 2002, The stationary motion of a one-axle vehicle along a circular curve with real rail and wheel profiles. Vehicle System Dynamics, 37(1), 29-58]. The wheelset is subject to flange contact if an unbalanced force remains in a curve towards the high rail gauge face. The resultant force in the transverse direction includes the lateral force, the radial force, and the creep forces in addition to the effect of the frequent wheelset displacement due to the kinematic oscillation [Iwnicki, S., 2003, Simulation of wheel-rail contact forces. Fatigue Fracture Engineering Material Structure, 26, 887-900]. This article has focused on a potential variation in some of the forces cited when the wheelset is subject to backward and forward movements. A severe wear rate observed within the wheel flange region in Iranian Railways was investigated by operating a test bogie on a curvaceous track. An obvious improvement in the wear rate and wear pattern of the wheels was attained when the second test bogie encountered a bogie direction reversal procedure. This enhancement is considered in this article from the force analysis standpoint.     

重载车轮对机械性能要求的研究

介绍了大秦线车轮的服役表现,探讨了重载运输条件下车辆轴重增加对车轮钢种特性的要求。根据重载运输条件,提出了我国重载车轮的研发思路,并据此进行了试验钢的开发,完成了实验室和工业性试制。检验分析结果表明,试验钢的性能指标基本上达到了预计目标,开发符合设计思路。     

舰船复杂设备的经济维修策略

复杂设备的故障率遵循德雷尼克定理,即故障率随着时间的增大而趋于平均故障间隔时间的倒数l/MTBF。对舰船复杂设备一般部件故障采用事后维修,而对于其关键部件的多项主要故障模式的维修,可建立逻辑树,运用最小割集的方法确定能够解决所有故障原因的最小预防工作集合,并在这众多的最小预防工作集合中依成本选择最经济的工作集合。     

基于集对分析的膨胀土路堤设计方案评价研究

集对分析是处理不确定性问题的系统理论新方法。利用该方法以某路提出的4种膨胀土路堤填筑方法为研究对象，从系统工程的角度出发，以设计方案的技术、经济和环境影响等作为评价因子，对几种填筑方法做出较全面的分析比较。     

舰用设备技术状态综合评估的结构完整性模型

讨论了机械设备技术状态评估的作用和技术状态评估方法的现状，以某汽轮给水泵机组这一舰用蒸汽动力装置的关键设备为对象，讨论了其结构完整性定义，并提出了从结构偏差上综合评估其技术状态的方法与实用模型，可指导类似设备技术状态评估模型的建立。     

我国高速铁路轮轨系统尚应深入研究的几个技术问题

高速铁路轮轨系统技术是确保列车高速行驶安全的关键。轮轨系统技术条件的影响因素 ;最高行车速度、运输组织、机车车辆和线路结构等重大问题应深入研究。本文结合日、德等国高速铁路情况 ,提出设计运营工作中存在的问题 ,可供立题研究。     

踏面测量时测头半径误差补偿方法的研究

探讨了铁路领域中踏面接触式测量中的测头半径误差补偿问题,也即求由离散数据构成曲线的等距曲线问题.在分析研究曲线等距偏移的基础上,选取B样条曲线逼近和三点共圆的曲线偏移方法,通过Matlab编程实现并检验了该两种方法.证实三点共圆法程序简单、算法稳定、准确度高且易于实现,能够很好地提高踏面测量的精度.建议采用三点共圆法作...     

A novel method to model wheel–rail normal contact in vehicle dynamics simulation

An approximate analytical method is proposed for calculating the contact patch and pressure distribution in the wheel–rail interface. The deformation of the surfaces in contact is approximated using the separation between them. This makes it possible to estimate the contact patch analytically. The contact pressure distribution in the rolling direction is assumed to be elliptic with its maximum calculated by applying Hertz' solution locally. The results are identical to Hertz's for elliptic cases. In non-elliptic cases good agreement is achieved in comparison to the more accurate but computationally expensive Kalker's variational method (CONTACT code). Compared to simplified non-elliptic contact methods based on virtual penetration, the calculated contact patch and pressure distribution are markedly improved. The computational cost of the proposed method is significantly lower than the more detailed methods, making it worthwhile to be applied to rolling contact in rail vehicle dynamics simulation. Such fast and accurate estimation of contact patch and pressure paves the way for on-line modelling of damage phenomena in dynamics simulation packages.