横风下高速列车系统动力学的平衡状态法

基于车辆-轨道耦合动力学和空气动力学提出了一种快速计算横风下高速列车系统动力学行为的平衡状态方法.首先,忽略轨道不平顺并利用流固耦合联合仿真方法计算横风下高速列车的平衡状态;然后,将平衡状态下的气动力加载到车辆-轨道耦合动力学模型并计算高速列车动力学响应.利用建立的平衡状态方法,研究了列车在速度为13.8 m/s的横风下以350 km/h速度运行时的流固耦合动力学行为.比较了平衡状态方法和联合仿真方法两种方法下列车姿态、安全性和舒适性指标的差异,计算结果差别在3.26%以内.研究结果表明:平衡状态方法计算横风下高速列车流固耦合的效率更高.     

智能手机检测车辆振动加速度数据预处理方法

通过所开发的手机端软件从智能手机中提取车辆振动加速度的过程中,为正确评价轨道平顺状态及车辆运行舒适性,需保障车辆振动加速度数据质量。本文依据概率统计方法与小波分析方法建立了异常值识别模型,采取中值滤波和小波滤波剔除因手机传感器性能稳定性和测试环境变化引起的随机误差,并结合成都地铁手机检测数据,验证两种滤波方法对手机检测数据随机误差的处理效果。实例分析表明：基于异常值识别模型可准确提取手机检测数据异常值位置,借用中值滤波和小波滤波剔除因外界环境变化引起的随机误差,保证了手机检测数据真实反映车体振动响应,为正确评价轨道平顺状态和车辆运行舒适性提供数据支撑。     

钢轨波磨对地铁车辆动力学响应的影响

建立地铁车辆-轨道耦合动力学模型,将钢轨视为弹性离散点支撑的无限长Timoshenko梁,将实测钢轨短波波磨不平顺数据作为不平顺激励.通过数值计算得到在科隆蛋扣件线路上不平顺发展过程中车辆动力学响应的变化情况.随着短波波磨不平顺幅值的增大,轮对和转向架的横、垂向加速度以及轮轨横、垂向力均呈增大趋势,且受不平顺程度的影响较大.结果表明钢轨波磨主要影响车辆系统的垂向振动.     

不同线路条件对车辆动力学性能的影响

为探查不同曲线半径和线路激励对车辆动力学性能的影响,应用动力学方法建立车辆-轨道系统动力学模型,计算各动力学评价指标的变化情况.研究结果表明:增加曲线半径有利于增加车辆通过曲线的安全性;车辆经过曲线线路连接处时脱轨概率较大,可重点考虑曲线线路连接位置车辆的运行状态;适当增大曲线半径可以减少轮轨间磨耗,有效降低车轮与轨道的磨耗速度;轨道激励变化对车辆临界速度的影响较大,可根据实际运行工况计算最佳临界速度范围.     

基于多体动力学的车辆道岔通过性能研究

道岔复杂的轮轨关系及其变截面特性是车辆通过道岔时引起振动甚至脱轨的关键因素.根据60kg/m钢轨18号可动心轨道岔设计布置图,在多体动力学软件中建立车辆—道岔耦合系统模型,在此基础上对车辆—道岔系统模型进行验证,仿真计算车辆侧向和直向通过道岔的动力学响应.结果表明转辙器区、辙叉区轨道截面变化和轮轨型面匹配是影响车辆动力学性能的主要因素.最后,对车辆侧向通过离散轨道模型工况下的动力学响应进行仿真计算,讨论道岔轨下整体刚度和阻尼对模型动力学性能的影响,为改善车辆通过道岔时的动力学性能、道岔轨下刚度与阻尼参数匹配提供理论基础.     

基于UM的磁浮列车-轨道梁耦合振动仿真程序开发

基于大型通用多体动力学仿真分析平台Universal Mechanism(UM),开发用于磁浮列车 轨道梁耦合振动仿真的专用程序UM Maglev,其中：磁浮列车设置为多刚体模型,弹簧和阻尼器的刚度和阻尼视为线性或非线性力元;轨道梁设置为三维铁木辛柯梁模型,或从外部有限元软件导入模态分析结果;轨道线路包含平面和纵断面曲线、超高和轨面随机不平顺;悬浮和导向系统控制采用PID模型;多体动力学系统微分 代数方程求解采用Park刚性稳定法。该程序可用于考察磁浮列车的曲线通过性能、运行平稳性和乘坐舒适度,研究悬浮/导向气隙与磁浮控制系统参数优化,分析轨道梁在动态电磁力作用下的振动响应。     

随机路面激励下整车NVH有限元分析

针对应用刚体动力学方法不能得到驾驶员可以直接感知的振动加速度的缺陷,提出应用整车柔性体模型进行汽车随机路面平顺性分析的方法.对一种典型路面不平度数据进行处理并将得到的功率谱密度(Power Spectral Density,PSD)作为激励,建立整车有限元模型,通过试验模态验证该模型后进行传递函数分析;根据所得的激励和传递函数的结果计算得出汽车方向盘处的速度响应.该速度响应与随机路面平顺性试验一致性较好。     

基于PCA和SVM的轨道不平顺状态识别

为快速识别轨道不平顺中存在的短波不平顺类型,提出基于主成分分析(PCA)和支持向量机(SVM)进行轨道不平顺状态识别的方法.首先提取轴箱加速度的特征参数,并采用主成分分析法对特征参数进行降维处理,提取出轨道不平顺的主元特征;然后构建支持向量机多分类器,以不同不平顺类型下轴箱加速度数据来验证模型的准确性;最后对实测数据进行轨道不平顺识别.通过对不同轨道不平顺下轴箱加速度的分析,结果表明该方法能够有效地实现一定区段内轨道不平顺类型的识别.     

基于JADE算法的钢轨接头病害故障检测研究

论文分析无缝铁路焊接接头对车辆安全行驶的影响。基于运营车辆的振动响应进行轨道不平顺检测具有效率高,成本低等优点。本文提出将盲源分离算法应用于车辆振动响应信号的分析,盲源分离算法在对振动响应信号直接进行处理,无需源信号的先验知识和信道的参数,降低了轨道接头特征信号提取的难度。通过对南京至宁启线路的轨道接头不平顺进行现场测试,并用matlab编程对测试结果进行分析。分析结果表明本文所采用的盲源分离算法能够较好的提取出轨道接头不平顺的特征信息。     

基于整车刚弹耦合模型的平顺性仿真与试验

车辆的平顺性车辆性能的一项重要评价指标,所以平顺性预测方案的有效性至关重要.根据车轮-悬架系统动力学方程和传递函数,并以某SUV(Sport Utility Vehicle)为原型,在adams/car中建立车身柔性体和其它各总成刚体模型装配得到整车刚弹耦合模型,进行车辆平顺性仿真分析.采用有限元软件hyperworks建立车身有限元模型,利用adams/processor对.振动加速度时间函数进行FFT(快速傅里叶变换)得到频域函数和功率密度函数,再通过matlab对数据进行处理得到两项平顺性评价指标aw和Law的值.应用便携式车载仪器对SUV进行道路试验,并用DH5902软件进行试验数据处理.将仿真与测试进行比较,结果可为车辆稳定性优化设计提供依据.     

基于路谱频域的车身疲劳分析

针对车身疲劳分析中静载法无法考虑结构动力学响应,瞬态分析法无法求解过长时间域的问题,将这2种方法与频域法进行比较,发现用频域法对大规模有限元模型进行动态疲劳分析相对容易,并能完全描述动力学响应过程.根据频域法进行振动疲劳分析的理论和计算过程,给出基于路谱频域的车身疲劳分析流程.基于功率谱密度（Power Spectral Density,PSD）载荷谱的传递函数法求解某车关键部件的疲劳寿命,求解结果与疲劳试验结果比较一致.结果表明基于路谱频域的振动疲劳分析方法在汽车结构疲劳计算中的应用可行.     

基于模型预测的自动导引车区间轨迹跟踪控制

针对自动导引车(AGV)轨迹跟踪问题,在确定其可行驶区域的基础上,考虑自动导引车的大小和形状,本文设计了一种基于模型预测控制理论的轨迹跟踪控制方法.首先,将车辆运动学模型进行线性化处理,得到车辆动力学线性模型;其次,运用模型预测控制方法,利用预测路径与期望路径之间的误差,通过优化得到使性能指标最优的控制序列;最后,在MATLAB软件上对轨迹跟踪控制器进行仿真.实验结果表明,AGV可以稳定地跟踪参考轨迹,且距离偏差和角度偏差都在给定的可行范围内,证明了提出的基于模型预测控制的轨迹跟踪算法具有良好的跟踪性能.     

基于小波包能量谱的钢轨扣件松脱检测研究

提出了基于小波包能量谱的钢轨扣件松脱识别方法,对获得的振动信号进行小波包分解,结合扣件松脱前后振动信号频域内能量变化,构造损伤指标(DI).在此基础上,开展了5种工况下的轨道结构动力响应测试,进行了轨道结构状态识别分析.实验结果表明:DI能够有效地识别轨道结构状态,且随着松脱程度的增加而增加;同一工况下得到的损伤指标DI变化波动均在±0.5以内,验证了该方法具有很好的鲁棒性和抗干扰能力.     

An approach for modeling long flexible bodies with application to railroad dynamics

Considering track flexibility in railroad vehicle simulations can lead to improved results. In modeling a railroad vehicle as a multibody system, track flexibility can be incorporated by using the floating frame of reference formulation (FFRF), which describes rail deformations in terms of shape functions defined in the track body frame of reference. However, the FFRF method is subject to two serious shortcomings, namely: it uses unreal track boundary conditions to calculate shape functions and requires a large number of functions to describe deformation. These shortcomings can be circumvented by defining shape functions in the trajectory frame of reference. Based on this notion, a new form of FFRF that can be used to describe the dynamics of long bodies subjected to moving loads (cable cars, zip-lines, elevator guides, pantograph catenary mechanism, etc.) was developed here. The shape functions selected in this work are based on the steady deformation exhibited by a beam on a Winkler foundation under the action of a moving load. However, other sets of shape functions more appropriate for transient dynamics are suggested. The definition of the deformation shape functions in a frame that moves with respect to the flexible body produces new terms in the generalized inertia forces of the flexible track. The proposed approach was applied to an unsuspended wheelset traveling on a tangent track supported on an elastic foundation. The results thus obtained under variable foundation stiffness conditions are discussed and comparisons made with the case of a rigid track. The new approach is also compared with the moving mass problem as solved with the mode superposition method.     

交通事故中车辆运动轨迹估计方法研究与仿真

研究交通事故中车辆的前期运动轨迹的准确估计问题。车辆在行进过程中轨迹随机性较强,一旦发生意外事故,会发生方向或者速度突变。运用传统方式进行事故中的车辆运动轨迹估计,方向或者速度突变会造成车辆运行线性变换参数与车辆运行轨迹估计参数存在差异,降低了车辆运动轨迹估计结果的准确率。为了避免上述问题,提出了一种物联网技术的交通事故中车辆运动轨迹估计方法。采用物联网技术,对事故中的车辆运动轨迹进行分析,运用轨迹突变参数融合将车辆运动参数数据进行统一处理,克服突变因素带来的影响。实验证明,利用物联网技术进行车辆运动轨迹估计,并取得了满意的效果,为保证车辆交通安全提供了科学依据。     

A Super-Element of Track-Wheel-Terrain Interaction for Dynamic Simulation of Tracked Vehicles

A track-wheel-terrain interaction model is presented in this paper, which can be used as a “force” super-element in a multibody dynamics code for dynamic simulation of tracked vehicles. This model employs a nonlinear finite element representation for the track segment that is in contact with the terrain and roadwheels, which can be used to simulate two different track systems, namely a continuous rubber band track and a multi-pitched metallic track, provided the finite element mesh in the track model is properly defined. The new track model accounts for the tension variations along the track (due to the non-uniformly distributed normal pressure and traction), track extensibility, and geometrically large (nonlinear) track deflections. A new solution algorithm is then proposed that includes an adaptive meshing method for representing track movement during the simulation for the multi-pitch tracks. Doing so produces a track model that captures high-frequency content of the track-wheel-terrain interaction, and it can more accurately describe the mechanics of a multi-pitch track as the vehicle negotiates rough terrain. The resulting track-wheel-terrain model combines approximate and known constitutive laws for terrain response with the new track representation, which allows the computation of the normal and shear forces, as well as the passage frequency, at the track-terrain interface. The track model and solution algorithm are further illustrated in this paper using a simple two-wheel system model and a full vehicle model of an M1A1 tank.     

Global sensitivity analysis of bogie dynamics with respect to suspension components

The effects of bogie primary and secondary suspension stiffness and damping components on the dynamics behavior of a high speed train are scrutinized based on the multiplicative dimensional reduction method (M-DRM). A one-car railway vehicle model is chosen for the analysis at two levels of the bogie suspension system: symmetric and asymmetric configurations. Several operational scenarios including straight and circular curved tracks are considered, and measurement data are used as the track irregularities in different directions. Ride comfort, safety, and wear objective functions are specified to evaluate the vehicle’s dynamics performance on the prescribed operational scenarios. In order to have an appropriate cut center for the sensitivity analysis, the genetic algorithm optimization routine is employed to optimize the primary and secondary suspension components in terms of wear and comfort, respectively. The global sensitivity indices are introduced and the Gaussian quadrature integrals are employed to evaluate the simplified sensitivity indices correlated to the objective functions. In each scenario, the most influential suspension components on bogie dynamics are recognized and a thorough analysis of the results is given. The outcomes of the current research provide informative data that can be beneficial in design and optimization of passive and active suspension components for high speed train bogies.     

Study of the dynamic vehicle-track interaction in a railway turnout

This paper analyzes the vertical dynamic response of a railway track subjected to traffic loads in a turnout, especially around the switch blades and the crossing nose. In order to study the influence of vehicle and track parameters on the vehicle-track dynamics, a numerical feedback interaction between a multi-body model of the vehicle and a 3D finite elements model of the track is carried out. For this purpose, two different models are developed. In the first one, the track is modeled by means of a FE model in the time domain through ANSYS software; while in the second one, the vehicle is simulated as a multi-body model by means of VAMPIRE PRO software. The influence of different parameters (e.g., speed, sprung masses, track stiffness and vehicle eigenfrequencies) on the generation of dynamic loads in a turnout, especially in the switch blades and the crossing nose, is studied. Finally, the vibrations induced by the passing of the vehicle are calculated for different scenarios.