Solving conformal contacts using multi-Hertzian techniques

Recently, publications aiming at wheel–rail contact surveys let readers think that multi-Hertzian methods present severe drawbacks with respect to ‘virtual penetration’ methods. These surveys criticise multi-Hertzian solutions mainly because presenting ‘larger contacts overlaps’ and ‘frequent secondary contacts near the border of the first contact’, both obvious geometric possibilities of which the practical occurrence and eventual inconvenience would remain purely theoretical unless established over definite methods demonstrating poor practical results. Recent surveys all quote Piotrowski–Chollet 2005 survey of wheel–rail contact models that attempted to illustrate defective multi-Hertzian techniques by concentrating on the method initiated by Sauvage in the 1990s and further developed by Pascal. The 2005 paper not only gives no evidence of practical inconveniences of Sauvage’s method but also confuses static geometric contact overlaps with the dynamical overlapping of forces. In reality it mixes Sauvage method up with a quite different technique. Thus a clarification is now necessary by reminding what the proper Sauvage technique really is and by showing some of its practical successful applications. The present paper, focusing on determination of normal contact forces in conformal situations, intends to explain clearly the advantages of the unequivocal localisation of secondary ellipses in that multi-Hertzian method which has been developed in INRETS VOCO codes in the 1990s and successfully used by SNCF and ALSTOM in the INRETS-SNCF code, VOCODYM, and later in Pascal’s online calculation of railway elastic contacts code. It proved its effectiveness for studying freight wagons derailments as well as rail wear and head-check, unrounded wheels wear, high-speed lines’ deformations or TGV comfort. While simulating American ACELA trainsets’ behaviour on the US North-East Corridor tracks, prior to actual tests, as part of the commercial contract. It has been also a major tool for bringing back together French and American Safety Standards.     

Single wheel hub motor failures and their impact on vehicle and driver behaviour

This research work studies the impact of single wheel hub motor failures on the dynamic behaviour of electric vehicles and the corresponding driver reactions. An experimental study in a moving-base driving simulator is conducted to analyse the influence of single wheel hub motor failures for motorway speeds. Driver reaction times are derived from the measured data and discussed in their experimental context. The failure is rated objectively on the dynamic behaviour of the vehicle and compared to the subjective evaluation. Findings indicate that critical traffic situations impairing traffic safety can occur for motorway speeds. Clear counteractions by the drivers had to be taken.     

上海松江叶榭塘水利枢纽工程设计

对上海松江区叶榭塘水利枢纽工程的特征参数、平面布置与主体结构型式及枢纽运行安全控制进行了详细的阐述。设计中对枢纽功能与环境景观的和谐统一、结构优化以及实现枢纽运行自动化控制方面有充分的考虑与尝试。     

上海南站的综合交通换乘系统

详细介绍了铁路上海南站综合交通枢纽的总体布局和换乘系统,包括铁路与城市轨道交通、道路公交、出租车、自行车、私人小汽车、长途汽车、社会车辆之间,轨道交通与道路交通之间的各种换乘流线与换乘距离。通过分析比较得出:上海南站在换乘的布局设计上比既有的大型铁路客站有很多改进,但与国外优秀的交通枢纽布局设计相比仍有一些不足,主要是没有充分利用铁路股道下面的空间进行立体换乘。目前,我国城市交通枢纽尤其是城市综合交通枢纽的换乘问题日益突出,而枢纽换乘质量的关键取决于其布局设计方案的质量,该案例的分析结果对我国综合交通枢纽系统的布局规划设计有参考意义。     

基于子系统划分的铁路枢纽能力利用率评价方法

针对铁路枢纽能力利用率评价问题,从铁路枢纽的运输组织特性出发,将枢纽划分为客运、货运、行车、编解等子系统,构建枢纽子系统-构成要素-评价指标3个层次的指标体系.按照各指标项的适中型特征构造评价得分函数,设计包括子系统权重、构成要素权重和指标权重的层次化权重设置方法,建立基于子系统划分的枢纽能力利用率评价方法.开发了枢纽...     

大型国际赛事条件下客运枢纽方案设计研究——以2022年北京冬季奥运会崇礼客运枢纽为例

大型国际赛事对客运枢纽的要求较高，客运枢纽既要满足城市功能和交通功能，又要满足赛事期间的服务功能和保障功能。以2022年北京冬季奥运会配套设施——崇礼客运枢纽为例，从设计理念和原则、规划定位和建设规模、交通组织、场站功能布局、站房建筑等方面，探索了大型国际赛事条件下客运枢纽设计策略。     

长沙西站高铁枢纽片区交通规划研究

针对现状城市交通与高铁枢纽接驳耗时过多问题，以长沙西站高铁枢纽为例，研究提出高效的进出站快速集散系统，以协调整个城市的对外交通。首先，对大型交通枢纽片区的外部和内部快速集散系统进行了深入研究。一是对服务于高铁枢纽旅客进出站的快速集散道路交通系统进行研究，提出“双井”模式，适合于客流量大且客流来向分散的大型交通枢纽；二是对内部到达高铁枢纽的小汽车、出租车交通的进出站模式进行了分析探讨。其次，对站前广场周边各类交通设施布局进行研究，确保枢纽服务范围内的交通高效可达。最后，对服务于高铁周边商务区的地下环路交通的必要性进行了探讨，并提出了地下环路适用情况和单向逆时针交通组织方式，通过地库联络线连通周边地块，利用立体交通组织的方式，从空间上分离高铁枢纽进出站交通与周边商务区交通，减少交织，提高高铁枢纽片区交通效率。     

特种车辆重载电动轮用轮毂电机热特性分析及冷却水道优化

为了准确分析轮毂电机温度场，基于电磁场有限元分析，采用考虑旋转磁化及谐波磁场的方法计算铁耗，并计算了轮毂电机各部件生热率。采用基于有限体积法的流固耦合分析和基于热网络法的磁热耦合分析，分别计算了额定工况下轮毂电机温度场，将轮毂电机温升试验和仿真结果进行了对比。结果表明，基于有限体积法的流固耦合分析得出的绕组稳态温度计算误差为1.8%，基于热网路法的磁热耦合分析计算误差为2.5%，验证了两种温度场分析方法的正确性。对不同结构冷却水道的热阻和压降进行了理论分析，基于Pareto遗传算法对螺旋型水道进行多目标优化，在保证额定工况电机稳态温升基本不变的情况下使水道压降降低了22.9%。