An abnormal carbody swaying of intercity EMU train caused by low wheel-rail equivalent conicity and damping force unloading of yaw damper

Low-frequency carbody swaying phenomenon often occurs to railway vehicles due to hunting instability,which seriously deteriorates the ride comfort of passengers.This paper investigates low-frequency carbody swaying through experimental analysis and numerical simulation.In the tests,the carbody acceleration,the wheel-rail profiles,and the dynamic characteristics of dampers were measured to understand the characteristics of the abnormal carbody vibration and to find out its primary contributor.Linear and nonlinear numerical simulations on the mechanism and optimization measures were carried out to solve this carbody swaying issue.The results showed that the carbody swaying is the manifest of carbody hunting instability.The low equivalent conicity and the decrease of dynamic damping of the yaw damper are probably the cause of this phenomenon.The optimization measures to increase the equivalent conicity and dynamic damping of the yaw damper were put forward and verified by on-track tests.The results of this study could enrich the knowledge of carbody hunting and provide a reference for solving abnormal carbody vibrations.

道岔冲击激扰对高速动车组车体弹性抖动的影响分析

为探究高速动车组通过道岔区域后车体的弹性抖动,建立考虑车体弹性的高速动车组刚柔耦合动力学模型和道岔冲击激扰模型。根据模型分析道岔冲击激扰作用下车体的弹性振动响应特征,通过仿真复现高速车辆的抖车现象,并与现场测试数据进行对比。在此基础上,分析车辆过岔速度、道岔激扰个数和道岔间隔对高速车辆车体弹性抖动的影响规律。结果表明:道岔冲击会导致车体1阶菱形耦合共振;车辆过岔速度对车体弹性抖动有显著影响,当车速达到300 km/h时,车体出现明显弹性抖动;连续道岔激扰会使车体横向振动叠加放大;车体横向振动加速度与道岔间隔之间存在非线性关系,当道岔间隔在50~80 m范围时,车体弹性振动更剧烈。研究结果可为寻找控制高速车辆弹性抖动的有效措施提供一定理论参考。

柔性车体与构架对车辆振动响应的影响分析

文中为在车辆多体动力学仿真中将车体和构架考虑成柔性体,使用有限元子结构分析,对车体和构架有限元模型进行缩减。通过刚柔耦合多体动力学仿真,获得车辆线路实际测点处振动加速度响应,并与实测数据进行对比,研究柔性车体与构架对车辆振动响应的影响。研究结果表明:相对于多刚体动力学模型,将车体和构架柔性化处理后进行仿真,车辆在更多频率处的振动响应会增大,计算得到的测点振动加速度均方根值也更大,与实测数据更接近,证明了在进行车辆系统动力学分析时将车体和构架考虑为柔性体的必要性。

基于子模型的镁合金车体刚度联合优化

以提升镁合金车体底架边梁刚度为目标,提取车体底架边梁边界,建立边梁子模型,对结构进行拓扑优化,获得边梁型材分布;在此基础上采用HyperStudy软件,进行试验设计,建立关于应变能、质量的边梁尺寸形状协同优化代理模型,开展边梁结构型腔多目标优化,同时对最优构型进行刚度分析验证。结果表明:相比原结构,车体边梁最大下挠减小18.47%,刚度明显改善,通过结构优化可有效补偿镁合金车体刚度下降。

新型中低速磁浮车辆动力学特性分析

针对一种速度160 km/h新型中低速磁浮悬浮架,文章运用SIMPACK多体动力学软件建立了车辆的动力学模型,分析了该悬浮架在直线以及曲线工况下的动力学特性。结果表明,直线运行工况下车辆速度可以达到160 km/h,悬浮间隙、车体振动加速度等指标均符合要求,但在120 km/h时车辆各项指标有所恶化,为减小车体共振影响,对车体振动加速度进行了频率分析并给出优化建议。在曲线工况下,车辆的导向力、空簧横向位移及滑台位移等指标均在正常范围。研究结果证明新型中低速磁浮车辆的动力学性能符合要求,相关动力学结果可为新型悬浮架后续研究及工程化提供数据支持。

铝合金车体结构自动参数化建模及刚度分析

基于铝合金车体断面CAD图纸,提出了快速、全自动提取车体断面中线和厚度的方法,并实现了断面中线分组、网格划分、厚度、材料属性的自动生成和赋值。在此基础上,基于MATLAB软件自主开发了铝合金车体结构建模和刚度分析专用软件。专用软件可利用车体梁柱截面的CAD图纸,自动建立车体的门、窗、牵引梁、枕梁、缓冲梁、门立柱、端墙结构的有限元模型,并实现与车体断面有限元网格的自动完全匹配。同时,自动施加约束和载荷并形成分析工况,从而建立整车结构的参数化有限元模型,实现车体结构刚度的快速有限元分析。通过与人工创建的车体结构有限元模型刚度对比,验证了基于上述方法自动建立参数化铝合金车体结构有限元模型的正确性。

板式轨道线路对机车垂向振动影响

高速列车在板式轨道线路运行时,板式轨道激振所引起的特定通过频率加剧了车体垂向振动,特定条件下引起车体垂向共振,恶化高速列车垂向平稳性并造成车体结构疲劳破坏。实际运营过程中,在板式轨道线路,动力集中动车组动力机车垂向振动剧烈。针对此现象,文章利用UM软件建立了考虑柔性车体、钢轨弹性及轨道板弹性的机车-板式轨道耦合系统动力学模型,分析了机车通过板式轨道时的垂向振动特性。研究表明:通过板式轨道时机车车体垂向振动响应大于非板式轨道线路,轨道板通过频率及其二倍频率振动响应明显,机车在140~160 km/h速度时车体一阶垂弯振动加剧;相对于非板式轨道线路,机车以160 km/h速度在板式轨道线路运行时,在线路不平顺激励及车轮一阶不圆激励工况下,车体垂向振动加速度分别增加8%和25%。

基于灵敏度分析的动车组车体结构模态提升研究

[目的]为全面了解车体零件尺寸参数对车体模态的影响,对动车组车体模态灵敏度进行分析,以提升车体主要振动频率。[方法]根据灵敏度计算结果,制定了8种单变量厚度提升方案,进行车体结构主要模态对比分析;在此基础上,对主要振动模态影响最大的零件进行两两组合,在质量增加不大的前提下,制定了3种提升方案来研究多变量厚度变化对车体主要振动模态的影响。[结果及结论]侧顶板、圆顶板、侧墙板、侧墙梁柱、车顶弯梁、波纹地板和底架边梁的厚度对车体主要振动模态的灵敏度较高;增加以上单变量影响因素的厚度和多变量影响因素的厚度,车体结构主要振动模态频率相对于原结构均有一定提升;与单变量厚度影响因素方案相比,多变量厚度提升方案的各振动模态频率均有所上升,但变化幅值较小,大大低于2个单变量厚度影响因素单独对车体模态影响的叠加。

城市轨道交通车体垂向振动对弓网受流性能的影响

[目的]既有对接触网系统动力学仿真的研究大多基于受电弓底座仅有纵向自由度的假设,忽略了轮轨激励引起的车体垂向振动对弓网受流性能的影响,需要将车辆-受电弓-接触网(以下简称“车-弓-网”)作为一个整体予以研究。[方法]分别建立了刚性接触网、柔性接触网两种接触网类型下的弓网耦合动力学模型及车-弓-网多体动力学模型。在案例线路上进行了弓网动态受流试验,对所建的刚性接触网车-弓-网多体动力学模型的计算结果进行了可行性验证。基于列车运行速度为80 km/h、90 km/h、100 km/h、110 km/h及120 km/h五种速度工况,选取了其中两种速度工况对刚性接触网受电弓绝缘子底座处的垂向动态响应进行了分析,并在五种速度工况下分别对两种接触网类型下弓网模型、车-弓-网模型的各动态响应参数进行了对比分析。[结果及结论]所建车-弓-网多体动力学模型的模拟计算结果是合理的。车体振动会对弓网受流性能产生一定影响:柔性接触网下车体垂向振动对弓网受流性能影响很小,可不予考虑;刚性接触网下,与未考虑车体垂向振动的弓网模型相比,考虑了车体垂向振动的车-弓-网模型计算得到的弓网接触压力统计最小值、弓头最大抬升位移均随列车运行速度的增加而增加,弓网接触压力统计最小值变化率的最大值为24.7%,弓头最大抬升位移变化率的最大值为4.2%。

基于BS 7910—2019标准的地铁车辆车体焊缝裂纹安全寿命评估

[目的]针对上海轨道交通铝合金车体焊接裂纹问题,探索科学合理的裂纹安全评估方法,这对保障列车的安全运营具有重要意义。[方法]通过BS 7910—2019中失效评估图和断裂力学理论,构建了一套适用于铝合金车体焊缝裂纹的安全寿命评估模型,并以上海轨道交通01A01型列车TC(带司机室拖车)牵引梁的10 mm焊缝表面裂纹为评估对象,进行铝合金车体焊缝裂纹安全寿命评估实践。[结果及结论]该车车体焊缝裂纹尺寸处于可接受的安全范围内,安全临界裂纹尺寸为45.8 mm,剩余安全寿命为3.8年。对该裂纹可采取每半年检查1次的维保策略,在列车退役前不必进行其他修复措施。评估模型已考虑到车体结构及载荷的复杂性,采取的保守估计方法能在确保安全性的前提下做到定量预测。评估模型可为生产实践提供指导,对裂纹状态管控红线的划定具有重要价值。建议在列车大修时,对车体进行全面的状态评估,包括车体探伤、材料分析、载荷数据收集,为后续裂纹安全寿命评估积累基础信息。

碳纤维磁浮车体强度及无损检测技术研究

碳纤维磁浮车体结构复杂,在服役过程中承受复杂载荷的作用,为评估碳纤维磁浮车体的强度特性,提出了碳纤维复合材料强度和超声相控阵无损测试方案。首先对车体进行了整车无损检测,检测车体在制造工艺和装配过程中产生的初始缺陷。然后对车体进行了强度试验,验证车体的结构强度是否满足设计要求,每个强度试验工况后对结构异响区域、应力异常区域和高应力区域进行了超声相控阵无损检测,确认试验过程中的车体状态。最后对车体再次进行了整车无损检测,确认车体完成强度试验后的车体状态。测试结果表明,碳纤维磁浮车体结构满足强度要求,无损检测结果满足评定准则要求。所提出的碳纤维复合材料强度及超声相控阵无损测试方法,可以有效满足碳纤维磁浮车体静强度测试。

气动载荷对高速列车车体强度的影响研究

随着列车运行速度的提高,气动载荷对车体强度的影响越来越显著。文章以某动车组车体为研究对象,首先基于有限元分析软件建立了车体有限元模型,然后参照其模拟仿真的明线会车压力波数据,采用时间积分的方法将车体测点瞬态压强转化为整个侧墙表面的气动载荷,依次加载多工况载荷来模拟整个会车过程,最后在车体上选择“关注点”,对比气动载荷加载前后“关注点”当量应力,分析计算气动载荷对车体强度的影响。试验结果表明,气动载荷对车体门角、窗角及车顶设备安装处强度影响较大,最大强度贡献率达到了37.3%,出现在第三车窗窗角处。在车体强度评估过程中考虑气动载荷是相当有必要的,通过时间积分可将瞬态压力波转化为多工况来模拟会车过程中的气动载荷作用。

基于铆接结构的模块化平车车体结构探讨

文章提出了一种基于铆接和模块化的铁路平车设计理念,阐述了铆接结构和模块化的优势,详细介绍了该新型平车的结构特点和设计思路,为铁路货车设计提供了新的方向。

高速列车运行时车体传热系数K值研究

车体传热系数K值是轨道车辆热工性能的重要指标,是高速列车空调系统能耗的重要影响参数。文章主要采用数值计算的方式,研究了高速列车车体传热系数K值。通过计算高速列车中间车的静止车体传热系数K值及运行条件下的车体传热系数K值,分析了不同运行速度时高速列车中间车车体传热系数K值的变化规律。计算结果表明:列车运行速度越高,车体传热系数K值越大,但增加幅度越来越小。此外,文章还分析了车体传热系数K值的变化对整车空调系统能耗的影响:高速列车以时速380 km运行时,相对于静止状态,由车体传热系数K值增大引起的整车空调系统能耗增加值不大。在设计高速列车时,相对于车体传热系数K值,更应注重列车高速运行时车体气密性。虽然车体传热系数K值增大引起的整车空调系统能耗增加值不大,但通过车体传入车内的热量仍较大,高速列车车体传热系数K值仍需控制在合理的范围内。

Carbody Structural Lightweighting Based on Implicit Parameterized Model

Most of recent research on carbody lightweighting has focused on substitute material and new processing technologies rather than structures. However, new materials and processing techniques inevitably lead to higher costs. Also, material substitution and processing lightweighting have to be realized through body structural profiles and locations. In the huge conventional workload of lightweight optimization, model modifications involve heavy manual work, and it always leads to a large number of iteration calculations. As a new technique in carbody lightweighting, the implicit parameterization is used to optimize the carbody structure to improve the materials utilization rate in this paper. The implicit parameterized structural modeling enables the use of automatic modification and rapid multidisciplinary design optimization （MDO） in carbody structure, which is impossible in the traditional structure finite element method （FEM） without parameterization. The structural SFE parameterized model is built in accordance with the car structural FE model in concept development stage, and it is validated by some structural performance data. The validated SFE structural parameterized model can be used to generate rapidly and automatically FE model and evaluate different design variables group in the integrated MDO loop. The lightweighting result of body-in-white （BIW） after the optimization rounds reveals that the implicit parameterized model makes automatic MDO feasible and can significantly improve the computational efficiency of carbody structural lightweighting. This paper proposes the integrated method of implicit parameterized model and MDO, which has the obvious practical advantage and industrial significance in the carbody structural lightweighting design.

Effect of Train Carbody's Parameters on Vertical Bending Stiffness Performance

Finite element analysis（FEA） and modal test are main methods to give the first-order vertical bending vibration frequency of train carbody at present, but they are inefficiency and waste plenty of time. Based on Timoshenko beam theory, the bending deformation, moment of inertia and shear deformation are considered. Carbody is divided into some parts with the same length, and it＇s stiffness is calculated with series principle, it＇s cross section area, moment of inertia and shear shape coefficient is equivalent by segment length, and the fimal corrected first-order vertical bending vibration frequency analytical formula is deduced. There are 6 simple carbodies and 1 real carbody as examples to test the formula, all analysis frequencies are very close to their FEA frequencies, and especially for the real carbody, the error between analysis and experiment frequency is 0.75%. Based on the analytic formula, sensitivity analysis of the real carbody＇s design parameters is done, and some main parameters are found. The series principle of carbody stiffness is introduced into Timoshenko beam theory to deduce a formula, which can estimate the first-order vertical bending vibration frequency of carbody quickly without traditional FEA method and provide a reference to design engineers.

Identifying the relationship between suspension parameters of underframe equipment and carbody modal frequency

As a critical component of the railway vehicle, underframe equipment has a great influence on the ride comfort of railway vehicles due to their big mass and active vibration. Therefore, study on the relationship between suspension parameters of underframe equipment and the modal frequency of carbody is extremely crucial for con trolling the ride quality of railway vehicles. In this paper, a finite element model of the carbody was developed to investigate the effects of the suspension location, the mass of the suspension equipment, and the suspension frequency on the mode of the carbody. Then, the matching relationship between the suspension parameters and the modal frequency of the carbody was studied through the transfer function. In addition, roller rig tests were performed to verify the numerical simulation model of the carbody. The results show that the suspension parameters of the underframe equipment have a great influence on the mode of the carbody, especially for the frequency of the first bending mode. To improve the frequency of carbody highfrequency bending and reduce energy transfer, equipment with a large mass should be suspended toward the middle of the carbody. The weight of the equipment strongly affects the first bending frequency and energy transfer of the carbody. The frequency of heavy suspended equipment should be sufficiently low to increase the transmissibility of high frequencies and improve the vibration characteristics of the carbody. Although the bending frequency of the carbody can be improved effec tively by increasing the suspension stiffness of thesuspension equipment, in order to reduce carbody vibration effectively, the suspension frequency of the equipment should be slightly lower than the carbody bending frequency.

Influence of equipment excitation on flexible carbody vibration of EMU

To study the vibration transmission character istics of a flexible carbody and its suspended equipment, a vertical mathematical model of highspeed electric multiple unit was established with equipment excitation considered. And the dynamic unbalance and impact turbulence excita tion from equipment were taken into account in a single stage and twostage vibration isolation system, respectively. Results show that the excitation transferred to carbody increases with suspension stiffness but decreases with the equipment mass increasing; the vibration transmission can be reduced by increasing the equipment mass or reduce the suspension stiffness. To avoid vibration resonance, the dynamic unbalance frequency of equipment should be out of the possible range of the carbody flexible modes, and a small stiffness should be applied to reduce the impact tur bulence. A small stiffness, however, would result in a large movement of the equipment which is limited by the static deflection requirement, while a great stiffness will transfer high frequency vibration. Therefore, a preferred stiffness should make the suspension frequency of equipment a bit greater than the first bending mode of carbody. Additionally, a 3D rigidflexible coupled dynamics model was built to verify the mathematical analysis, and they show good agreements. Results show that a twostage isolation could reduce the excitation transmission and make the vibration of carbody and equipment acceptable.

Optimization and static strength test of carbody of light rail vehicle

Preliminary structure of light rail vehicle (LRV) carbody made of steel was designed considering its usage, strength, manufacturing, etc. Based on the finite element analysis, the optimization of design parameters associated with thickness of LRV carbody is carried out to increase the whole strength of the carbody and to reduce its mass. With the aids of the substructure technique and the modified technique with discrete variables in the optimization based on the finite element method, the consumed computing time is reduced dramatically. The optimized LRV carbody is re-analyzed by FEM to obtain its static strength and vibrating mode and is manufactured. The mass of the optimized carbody reduces about 1.3 kg, and the relative reduction ratio is about 10%. Then, the strength test of the real carbody under the static load is executed. It is shown by the numerical and test results that the design requirements of the LRV carbody are satisfying. The newly designed carbody is used in the LRV, which is the first one used commercially developed by China independently. Nowadays, the LRV is running on the transportation circuit in Changchun of China.

纵向冲动对弹性城轨车辆运行舒适度影响研究

以某地铁B型车为研究对象,基于SIMPACK软件建立由弹性车体结构耦合的刚柔耦合列车动力学模型。对比不同运行工况下的仿真计算结果,探究由于坡道线路和牵引制动而产生的纵向冲动对弹性城轨车辆运行舒适度的影响。结果表明:在牵引力、制动力或坡道附加阻力的影响下产生的纵向冲动使得弹性城轨车辆的舒适度值增大52.87%~163.69%。同时,纵向冲动对车体底架上前、后测点舒适度影响的增大以及牵引制动时弹性车体底架中间测点舒适度值出现的负增长,说明了在评价运行舒适度时考虑车体自身结构弹性的必要性。