The impact of structural flexibilities of wheelsets and rails on the hunting behaviour of a railway vehicle

The hunting motion of a passenger coach is investigated using a multibody system in which the wheelsets and the rails can be modelled as flexible bodies. By comparing the results for different model variants, in which the structural flexibilities of the wheelsets and of the rails are either taken into account or neglected, the impact of the flexibilities is analysed. It turns out that the flexibilities of both the wheelsets and the rails have a significant impact on the hunting behaviour by increasing the lateral motions of the wheelsets and lowering the critical speed. In order to investigate the impact of the flexibilities under different operating conditions, the calculations are carried out for track geometries using different rail profiles (60E1, 60E2) and different rail cants (1:40, 1:20) and for different values for the friction coefficient (0.25…0.4) at the wheel–rail contact. The results show that the influence of the flexibilities is the strongest for high lateral forces, which occur e.g. for contact geometries leading to high hunting frequencies and for high values of the friction coefficient. The results also show in some cases a strong impact of the flexibilities on the position of the wheel–rail contact on the running surface of the rail, which is of particular interest with respect to wear simulation.     

细粒土路基平衡密度状态分析

为掌握细粒土路基的平衡密度状态及其变化原因，统计分析9条高速公路路床顶部的压实度和含水率检测资料，对3条黄泛区高速公路路基的压实度、含水率以及1条高速公路的路基模量进行全断面深度检测，并开展非饱和细粒土的湿化试验和弹性恢复试验。现场实测发现：在役路基除了实测含水率较最佳含水率有0~13.8%的增加外，相应的压实度出现了0~10%的线性衰减；其中，路床区、上路堤以及受水位波动影响较大的路基底部的压实度降低十分明显，而下路堤上部区域压实度基本维持不变甚至有所增大；路基压实度的变化与土的含水率密切相关。非饱和土三轴试验结果表明：土体湿化过程中，吸水导致体积膨胀和压实度衰减；当路床土吸湿至平衡湿度（含水率为18%）时，土体压实度降低5.07%。弹性恢复试验结果表明：压实路基土因变形恢复导致路基密度衰减；低含水率、高压实度和低上覆荷载条件下的弹性恢复较大，压实路床土弹性恢复导致的压实度降低值最大为0.5%；综合湿化和弹性恢复结果来看，两者占黄泛区路床区压实度衰减总量（约7%）的79.6%；此外，路基剪切模量的原位实测值较相同物理状态下的室内重塑土结果平均高出了60.64%，表明运营多年的高速公路路基土具有一定的结构性。因此，既有路基的评价应该同时考虑路基湿度增加、密度降低以及土体结构性等综合因素。     

北京地铁新线100km/h车辆热容量问题分析

对北京地铁新线100 km/h车辆热容量问题进行了分析,对4种基础制动装置的配置方案进行了探讨。     

Railway wheel-flat and rail surface defect modelling and analysis by time–frequency techniques

Damage to the surface of railway wheels and rails commonly occurs in most railways. If not detected, it can result in the rapid deterioration and possible failure of rolling stock and infrastructure components causing higher maintenance costs. This paper presents an investigation into the modelling and simulation of wheel-flat and rail surface defects. A simplified mathematical model was developed and a series of experiments were carried out on a roller rig. The time–frequency analysis is a useful tool for identifying the content of a signal in the frequency domain without losing information about its time domain characteristics. Because of this, it is widely used for dynamic system analysis and condition monitoring and has been used in this paper for the detection of wheel flats and rail surface defects. Three commonly used time–frequency analysis techniques: Short-Time Fourier Transform, Wigner–Ville transform and wavelet transform were investigated in this work.     

开封地区湿软路基对路面的影响分析

该文针对开封地区湿软路基含水量高,强度低的状况,采用有限元方法分析了不同土基模量下路面的弯沉、层底拉应力等关键设计指标.计算结果表明,在土基模量较小时,路面控制指标仍然是弯沉;明确了开封地区湿软路基处治应达到的强度标准,可以为该地区路基处治提供技术参考.     

改善轮轨接触状态的车轮型面几何设计方法

改进了车轮型面设计方法,给出了设计方法的解析数学表达式,将轮对等效锥度与轮轨型面接触状态联系起来,对设计实例进行了轮轨几何接触、非赫兹滚动接触和车辆动力学性能分析.研究结果表明:轮轨接触点能够均匀分散分布;由于接触斑面积增大约23%,最大接触压力降低约21%,使轮轨滚动接触应力降低了约20%;装备实例型面的车辆临界速度...     

土基模量对沥青路面性能影响分析

从沥青路面结构层施工质量控制、半刚性基层反射裂缝扩展、路面疲劳寿命三个方面分析了土基模量对半刚性基层沥青路面性能的影响规律,提出了沥青路面土基模量的合理设计和施工控制措施。     

LDJC型货车轮对尺寸自动测量机

介绍了货车轮对尺寸自动测量机的主要技术参数、结构及功能等。     

列车轮对在线动态测量方法的评述

论述了列车轮对参数在线动态测量方法研究的重要意义,介绍了国内外在线动态测量的常见方案,并探讨我国在线动态测量系统的发展和应用。     

Experimental and numerical investigation on the derailment of a railway wheelset with solid axle

This paper presents the results of an experimental and numerical investigation on the derailment of a railway wheelset with solid axle. Tests were carried out under quasi-steady-state conditions, on a full-scale roller rig, and allowed to point out the effect of different parameters like the wheelset's angle of attack and the ratio between the vertical loads acting on the flanging and non-flanging wheels. On the basis of the test results, some existing derailment criteria are analysed in this paper and two new criteria are proposed. A model of wheel-rail contact is proposed for the mathematical modelling of the flange climb process, and numerical vs. experimental comparisons are used to obtain model validation.