让火车飞起来

什么是磁悬浮列车 传统列车的支撑、导向以及牵引、制动等功能都是靠车轮和钢轨之间的相互作用来实现的;列车靠车轮支撑在钢轨上,列车在横向的导向是靠轮缘与钢轨内侧之间的相互作用实现的,而列车的启动和制动,加速和减速靠的则是车轮与钢轨之间的摩擦力.     

让火车飞起来

传统列车的支撑、导向以及牵引、制动等功能都是靠车轮和钢轨之间的相互作用来实现的；列车靠车轮支撑在钢轨上，列车在横向的导向是靠轮缘与钢轨内侧之间的相互作用实现的，而列车的启动和制动，加速和减速靠的则是车轮与钢轨之间的摩擦力。     

高速列车高阶车轮多边形磨耗机理的试验研究（英文）

目的:通过试验研究,对高速列车车轮多边形磨耗机理进行初步探究。创新点:以试验方法为基础,跟踪调查车轮多边形磨耗的发展规律,然后分别对轨道系统和车辆系统开展现场试验,对导致车轮发生多边形磨耗的因素进行排查,探明了车轮多边形磨耗的机理。方法:1.进行车轮多边形磨耗跟踪测试;2.进行轨道结构模态特性测试、钢轨波磨测试和轨道振动响应测试;3.进行转向架模态特性仿真研究、悬挂系统隔振特性测试以及车辆振动特性跟踪测试。结论:1.列车运行时,车轮受到周期性激励作用会发生多边形磨耗,且当激励波长整分车轮周长时,多边形磨耗发展迅速;2.作为主要激励源,轮轨接触表面出现的车轮偏心、钢轨表面不平顺、轨下支承不均匀、钢轨接头和道岔等激发了转向架系统在550~600 Hz频段内的模态耦合共振,从而导致了车轮多边形磨耗的产生;3.变速运行可以有效地控制车轮多边形磨耗的产生与发展。     

浅谈外墙背栓式挂贴瓷板施工方案

外墙采用背栓式挂贴法,用背栓式方法,在瓷板背面打孔,将钢条固定在背栓上,用粘结剂采用满粘法将瓷板贴于墙上,然后用膨胀螺栓将钢条固定在墙上.外墙挂贴瓷板与苯板之间有100mm空气夹层,瓷板与瓷板及瓷与外窗之间均打密封胶使100mm空气夹层不流动起到节能作用.     

对机车制动工况的几点思考

一、机车在正常制动机画在制动中,制动缸中空气的压力,通过制动传动装置的传递和放大,使闸瓦以K千牛的力紧压滚动着的车轮,轮瓦之间产生的摩天楼擦力为K·φk千牛, φk是瓦轮间的摩擦系数,如图1所示,这时由于列车运动惯性力的作用,动轮便以 K·φk千牛的力作用于钢轨。假如在轮轨间粘着状态给轮对一个大小相等,方向相     

现代文阅读训练(三)(四)

2002年12月31日冠名为“VIP运行”的上海磁悬浮线首次试运行获得圆满成功。磁悬浮列车是在传统列车基础上发展起来的,但其构思颇为巧妙。传统列车的车轮要在钢轨上转动,是有机械接触的,而磁悬浮列车则是在钢轨上悬浮起来,有着一定的间隙,并没有机械接触,这就大大减少了运行阻力,从而可以大大提高运行速度。磁悬浮列车的基本原理是利用电磁吸力或电动斥力让列车悬于钢轨之上并进行导向,以实现列车与钢轨的无机械接触运行,从根本上克服了传统列车轮轨摩擦力限制、机械噪音等问题。磁悬浮列车基本上可分两大类:常导磁悬浮和超导磁悬浮列车。…     

滚动与摩擦

滚动,是一种常见的比较复杂的运动。当圆柱体(或圆球)在斜面上向下运动时,如果料面比较粗糙,圆柱体与斜面之间存在着足够大的摩擦力,那么圆柱体将向下滚动;如果斜面比较光滑,圆柱体与斜面之间的摩擦力不够大,那么就会出现有滚动,又有滑动的现象。可见,对于滚动来说,摩擦力起着重要的作用。     

高边坡的稳定性静力分析

针对目前诸多岩质高边坡稳定性评价方法都难以准确确定边坡失稳破坏时产生的最危险滑动面位置这一难题,利用有限元强度折减法,对岩质高边坡失稳破坏的最危险滑动面进行搜索,以便解决由滑动面位置不确切引起的工程设计与施工问题.     

导气管的简单固定方法

在九年义务教育《化学》(全一册)教材内“氢气还原氧化铜”实验中,对伸入装有氧化铜粉末的试管内的导气管的固定方法未作任何说明,因此,在做分组实验时,大多数学校采取让学生用手持的方法固定。这样做既不科学规范,又影响学生观察实验现象和记录有关内容,还能产生很多弊病。本文介绍一种简单的固定方法。ａ.材料工具:0.1ｍｍ厚的硬纸板,小刀,透明胶纸,两面贴胶纸。ｂ.步骤:①用小刀沿实线部分将硬纸板刻成如图1-(ａ)所示。②按图1-(ａ)所示虚线,折成图1-(ｂ)所示形状,并用透明胶纸缠绕固定。③用两面贴胶纸贴在圆弧表面的一部分,然后粘在试…     

关于滑动变阻器的两种基本接法

在高考物理实验题中,我们多次考查滑动变阻器的两种接法——分压式与限流式。但虽多次考查,仍有很多学生出错。为什么会出现这一现象?主要原因是学生没有掌握好两种连接方式的特点及作用,遇到具体问题时不知道该如何连接。     

高速列车车轮多边形对车内噪声的影响

研究目的：研究高速列车车轮多边形特征对轮轨噪声和车内噪声的影响规律,讨论目前国内高速列车车轮镟修指标的不足,为高速列车车轮镟修方法的优化改进提供科学依据。创新要点：系统分析高速列车车轮多边形阶次、幅值和相位等参数对车内噪声的影响规律;提出车轮镟修中仅考虑车轮径跳作为限值是不够的。研究方法：1．基于线路试验,初步分析高速列车车轮多边形状态对车内噪声的影响,进而对车轮多边形特征进行剖析;2．基于带通滤波和快速傅里叶变换,使用MATLAB程序生成不同阶次、幅值和相位的车轮多边形粗糙度数据;3．基于TWINS轮轨噪声原理,使用HWTNS预测含有不同车轮多边形特性的轮轨噪声;4．基于混合有限元-统计能量分析（FE—SEA）方法,建立高速列车客室端部车内噪声预测模型,预测车内噪声;5．通过分析车轮多边形参数、车轮径跳和车内噪声之间的相互关系,研究目前的高速列车车轮镟修指标是否合适。重要结论：1．高速列车车轮径跳值相同,但车轮多边形状态不同时,轮轨噪声与车内噪声有明显差异;2．当车轮多边形幅值相同时,高阶多边形可以引起更高的轮轨噪声和车内噪声;3．改变车轮多边形的相位,可以获得不同的车轮径跳值,但是对轮轨噪声和车内噪声几乎没有影响。     

不同速度高速列车车外噪声的调查研究

研究目的：基于声源识别,得出车外噪声分布特性及场点主要噪声源。创新要点：1．研究高速列车噪声源强特性及频谱特性;2．揭示不同速度下不同声源频谱变化规律;3．分析车外声场场点噪声变化规律及主要声源。研究方法：1．利用车外声源识别系统（图2）分析高速列车声源分布规律及频谱特性;2．利用声源的垂向（图10）分布研究不同声源在各频率下垂向分布规律;3．利用场点声源与速度的拟合关系（图16）研究场点主要噪声源。重要结论：1．高速列车车外噪声源主要分布在轮轨区域、受电弓和车间连接区域;2．轮轨区域噪声包括滚动噪声和气动噪声,在各频率均为最显著声源;3．在整个列车高度,轮轨滚动噪声对总噪声贡献率大于气动噪声;4．车外场点噪声主要频率为630-2500Hz,主要来自轮轨滚动噪声。     

固定辙叉区轮轨静态接触几何关系计算

针对固定辙叉特殊的轨线布置及复杂的轮轨接触关系,建立固定辙叉区轮轨接触几何关系算法,分析固定辙叉区沿辙叉走行方向主要接触参数的变化规律以及各关键断面轮轨接触点变化情况。结果表明:在辙叉轮载过渡段轮轨接触参数变化规律复杂,结构不平顺变化幅值最大且波长较短;轮对横移量增加,轮轨接触几何参数增大,轮轨动力作用增强;辙叉咽喉区和轮载过渡段辙叉侧轮轨接触点变化存在突变。提出应合理设计辙叉区轮载过渡段结构参数,优化轮轨接触几何关系,进而改善列车通过时辙叉的受力性能。     

Formation process,key influencing factors,and countermeasures of high-order polygonal wear of locomotive wheels

Two types of high power alternating current(AC) locomotive in China are prone to serious high-order polygonal wear, which has significant negative effects on the operation of locomotives. This study investigates factors influencing polygonal wear in locomotive wheels and determines methods of minimizing operation damage. We designed experiments to analyze the process of polygonization formation of wheels to identify the key influencing factors, finding that natural vibration of wheelsets is the central inherent factor of wheel polygonization and that these vibrations can be easily stimulated by wheel or rail irregularities. We found that poor re-profiling quality is the key external factor in these irregularities. The wheelset bending resonance is activated when the remaining wheel polygonal wear has a wavelength of 200 mm in the 1/3 octave band, in turn leading to significant increases of wheel polygonal wear. In this study, we review a new wheelset design that can mitigate and/or eliminate the polygonal wheel wear due to increased stiffness in wheel bending. We evaluate the potential capacity of the newly designed wheelset and propose two proven effective measures to further improve the wheel re-profiling quality for polygonal wear.     

Numerical investigation on wheel-turnout rail dynamic interaction excited by wheel diameter difference in high-speed railway

The wheel-rail relationship in turnout is more complicated than that in ordinary track. Profile wear and machining errors of the wheelset cause deviations of the rolling radius on different wheels. Therefore, wheelsets move to the direction of smaller diameter wheels in search of a new stable state and to change the condition before entering the turnout. The main aim of the present work is to examine the wheel-turnout rail dynamic interaction combined with the static contact behaviour. Calculations are performed on a high-speed vehicle CRH2 and the No. 12 turnout of the passenger dedicated line. The wheel-turnout contact geometric relationship and normal contact behaviour under wheel diameter difference are assessed by the trace principle and finite element method. A high-speed vehicle-turnout coupling dynamic model is established based on SIMPACK software to analyse the wheel-rail dynamic interaction, riding comfort, and wear. Both the wheel diameter amplitudes and distribution patterns are accounted for. The simulation shows that wheel diameter difference can greatly disturb the positions’ variation of wheel-rail contact points and affect the normal contact behaviour on switch rails by changing the load transition position. The effect of wheel diameter difference on wheel-turnout rail dynamic interaction can be divided into three according to its amplitude: when the wheel diameter difference is within 0–1.5 mm, the wheel flange comes into contact with the switch rail in advance, causing a rapidly increased lateral wheel-rail force; when it is within 1.5–2.5 mm, trains are subject to instability under equivalent in-phase wheel diameter difference; when it is larger than 2.5 mm, the continuous flange-switch rail contact helps strengthen the vehicle stability, but increases the wheel-rail wear. It is recommended to control the wheel diameter difference to within 2.5 mm but limit it to 2 mm if it is distributed in-phase.     

钢轨波磨处高速轮轨滚动接触行为与波磨发展的模拟研究

研究目的：为求解钢轨（短波）波磨处的高速轮轨瞬态滚动接触建立有限元模型,研究影响高速钢轨波磨发展的重要因素。削新要点：1．求解不同牵引条件下轮轨间的瞬态法和切向滚动接触问题,并考虑真实轮轨几何和钢轨波磨,最高模拟速度达500km／h;2．基于模拟结果,解释了中国高速线路上发现的钢轨波磨很快稳定下来的现象。研究方法：1．详细分析钢轨波磨处高速轮轨瞬态滚动接触的法、切向解以及由此导致的V-M等效应力和摩擦功沿轨面的波动;2．变化波磨波长、波深及重要滚动参数如速度和牵引系数等,研究它们对波磨处滚动接触行为的影响;3．对比上述有限元模型与传统多体动力模型在波磨处的法向轮轨力结果。重要结论：1．法、切向轮轨力及法、切向接触应力均随着波磨几何呈周期性波动,但相位略有差异,V-M等效应力和摩擦功的波动形式接近切向接触应力;2．牵引系数越大,波磨处V-M等效应力和摩擦功的波动范围越大;3．名义参数下,对于所研究高铁系统,波长为80mm左右、速度为250-300km／h时波磨的动态响应最大,这与现场观测相符;4．传统多体动力模型会高估钢轨波磨激励的法向轮轨力;5．钢轨波磨会逐渐稳定下来,通过速度越高进入稳定越快。     

高速铁路运营过程中的关键问题：轮轨磨耗等

随着高速铁路运营里程和列车运营速度的不断增长,出现了一些和列车轨道耦合大系统密切相关的关键科学和技术问题。这些问题不仅影响到列车的运行品质,甚至威胁到安全运行,是当前高速铁路运用和发展中急需解决的问题。本文系统描述了高速铁路在运营过程中所出现的一些关键科学和技术问题,并述评了全世界有关这些问题的研究进展、现状和不足之处,提出了今后有利于认识和解决这些问题的发展方向。在长期高速运营的铁路大系统环境中,这些问题的形成的机理、发生、发展过程和预防措施的研究,需要从列车／轨道耦合大系统运营环境（速度、路况、气候和运用维修）、系统的自身参数匹配、材料选用和运营成本等全面系统考虑,并从理论、技术、工艺、监控和维修等方面解决。     

Dynamic analysis of a high-speed train operating on a curved track with failed fasteners

A high-speed train-track coupling dynamic model is used to investigate the dynamic behavior of a high-speed train operating on a curved track with failed fasteners. The model considers a high-speed train consisting of eight vehicles coupled with a ballasted track. The vehicle is modeled as a multi-body system, and the rail is modeled with a Timoshenko beam resting on the discrete sleepers. The vehicle model considers the effect of the end connections of the neighboring vehicles on the dynamic behavior. The track model takes into account the lateral, vertical, and torsional deformations of the rails and the effect of the discrete sleeper support on the coupling dynamics of the vehicles and the track. The sleepers are assumed to move backward at a constant speed to simulate the vehicle running along the track at the same speed. The train model couples with the track model by using a Hertzian contact model for the wheel/rail normal force calculation, and the nonlinear creep theory by Shen et al. (1984) is used for wheel/rail tangent force calculation. In the analysis, a curved track of 7000-m radius with failed fasteners is selected, and the effects of train operational speed and the number of failed fasteners on the dynamic behaviors of the train and the track are investigated in detail. Furthermore, the wheel/rail forces and derailment coefficient and the wheelset loading reduction are analyzed when the high-speed train passes over the curved track with the different number of continuously failed fasteners at different operational speeds. Through the detailed numerical analysis, it is found that the high-speed train can operate normally on the curved track of 7000-m radius at the speeds of 200 km/h to 350 km/h.     

The critical loading for lateral buckling of continuous welded rail

INTRODUCTION The conventional design of rails uses steel clipboards and bolts to link rails, and avoids bucklingcaused by thermal expansion effect by mountingexpansion joints to solve axial restraint generated byseasonal or day-and-night temperature changes. Butthe discontinuity at the rail joints brings discomfortand noise to passengers when the train has suddenlystops or starts, during which train speed cannot beeffectively increased, rails are more easily damaged,and the cost of mainte…     

可调式手动压力机的设计与制造

该手动压力机是利用旋转的手轮和与手轮联接在一起的轴来带动压力机进行工作的小型压力设备。对其传动机构该手动压力机创新设计在于利用齿轮工作原理,将手轮,齿轮轴,齿轮,齿条相结合,手轮将人提供的力经过齿轮轴,齿轮,齿条以次传递给滑块,带动滑块上下移动,从而实现冲压的功能。