基于整车动力学模型的虚拟迭代技术分析

以Adams/Car建立的整车多体动力学模型为载体,并以在试验场测试得到的轮心加速度、悬架弹簧位移和轮心力作为整车虚拟迭代的实测信号。在FEMFAT.Lab软件中建立实测信号和轮心位移响应信号间的传递函数。通过传递函数反求出轮心位移,并作为输入载荷,仿真分解得到车身与底盘连接点动态载荷,作为后期虚拟疲劳试验的必要条件。     

轮心六分力作用下悬架疲劳载荷谱提取

准确提取车身连接点载荷是车身疲劳耐久性分析的关键.本文基于某轻型客车研发过程中单独对前、后车轮测取的道路试验轮心六分力数据,采用前、后悬架动力学模型提取车身连接点载荷,分析了多种悬架模型方案及其仿真结果,并与试验结果进行了对比.本文方法能够提取车身连接点载荷,为低成本准确获取车身疲劳耐久分析输入载荷提供了参考.     

基于灵敏度分析的客车车身质量优化研究

文中将灵敏度分析引入到客车质量优化中.首先建立了某承载式客车车身的有限元模型,确定其边界条件和载荷,并对模型进行了试验验证.接着选取车架上刚度和强度相对富裕的梁作为对象进行灵敏度分析.最后根据分析结果选取车身最大应力和位移作为状态变量,以车身总质量为目标函数,进行客车车身的质量优化.     

白车身静刚度测试系统开发

文章主要介绍某自主品牌轿车在白车身静刚度测试系统上做出的创新。其中包括试验样件的定义,车身的约束方式及相应的夹具实现,加载装置自动化及闭环控制系统。并根据在测量过程中碰到的具体困难,研发了一套全自由度位移测量装置,来测量车身及洞口的位移量测量。并通过实车的多次试验证明了该试验系统的可靠性及得到的数据的一致性。     

基于试验设计和响应面建模的轿车白车身模态多目标优化

结合了试验设计和响应面建模的方法来研究轿车白车身的模态频率优化途径。通过正交试验设计方法,计算了某轿车白车身模态对车身后部零件板厚的灵敏度,遴选出灵敏度较大的设计变量。在此基础上进行第二轮试验设计计算,进行响应面建模,在精度较高的响应面上进行了同时以扭转频率和重量为目标的优化计算。最终从一组帕累托最优解中选出了符合要求的零件板厚组合。总结出了一套高效的针对板厚设计的白车身模态频率优化方法与流程。     

汽车半粘接轮眉开胶问题分析与解决

轮眉半粘接结构为一种全新的SUV轮眉连接方式,新的连接方式给生产过程带来了诸多挑战。为了在项目初期解决轮眉开胶问题,基于鱼骨刺图,详细梳理了相关影响因素。通过系统地分析与试验,筛选出主要原因为车身凹扣热熔胶鼓包、轮眉及车身对手件的尺寸偏差、粘接表面清洁与粘接工艺不当等因素。针对主要问题,改进相关零件结构设计、优化零件尺寸、完善表面清洁与粘接工艺,快速解决了轮眉开胶问题。     

车身疲劳载荷谱获取关键技术研究

基于车辆动力学理论,研究车辆动力学模型构建和关键参数选取,通过分析车身约束、力矩分配及刚度阻尼参数选取等,提出组合车身约束、驱动和制动力矩分离、加载轮心力矩、限位块阻尼和衬套刚度阻尼模拟等关键技术及建立可靠动力学模型和获取精确疲劳载荷谱的技术方法,并与实测疲劳载荷谱进行对比验证其可靠性。     

基于试验的白车身刚度快速计算方法研究

为评价白车身的刚度,建立了白车身静态刚度试验模型,进行了试验设计.在此基础上开展了白车身的刚度测试,测得设定载荷在车身地板一组施力点上的挠度,并用若干多项式基函数对其进行拟合.通过比较拟合的标准偏差,最终选出一个相对最佳的挠度拟合多项式,代表白车身刚度的分布状况.借此可快速评估白车身刚度,为车身结构的优化提供良好的基础.     

轮毂电机驱动电动微型车车内噪声道路试验分析

通过道路试验的方法针对四轮轮毂电机驱动电动微型车车内噪声问题进行振源、传递途径以及主要贡献板件识别.分析中分别加速工况、回馈制动工况和匀速行驶工况下车内噪声和结构振动信号进行测量,通过对试验数据时间域、频率域、阶次跟踪分析发现:轮毂电机引起的6阶振动是车身结构振动和车内噪声的振源;不同频率范围内车身各结构板件对车内噪声有不同的影响并进行了相关的分析.试验结果对轮毂电机驱动电动车的进一步开发具有参考价值.     

某商用车白车身静刚度试验方法研究

本文介绍了商用车白车身静刚度的理论计算方法,以及静刚度的试验方法。通过某车身的静刚度试验实例,进一步阐述了商用车静刚度试验的全过程,包括如何约束、如何加载以及如何评价试验结果,为此类车的白车身静刚度试验提供了相应参考。     

汽车轮毂轴承及主销松旷间隙自动化检测方法探讨

对汽车轮毂轴承处、主销处存在的松旷间隙以及2种间隙的区分等进行了力学分析，提出了轮毂轴承及主销的配合间隙的自动检测方法。该方法是通过分析车轮在支承台板的带动下产生的位移和驱动力关系特征曲线实现的，基于该方法开发了自动化检验台。最后通过实车测试对该方法进行了验证。结果表明，检验台测试结果与百分表测量结果基本一致，最大相对误差不超过5％，满足了快速检验的精度要求。     

Numerical investigation on effect of the relative motion of stock/switch rails on the load transfer distribution along the switch panel in high-speed railway turnout

In railway turnout, the stock rail and switch rail are separated to enable the vehicle changing among the tracks, and they are provided with different rail resilience level on the baseplate. Therefore, there will be vertical relative motion between stock/switch rails under the wheel loads, and the relative motion will affect consequentially the wheel–rail contact conditions. A method is developed to investigate the effect of the relative motion of stock/switch rails on the load transfer distribution along the switch panel in high-speed railway turnout. First, the rigid wheel–rail contact points of stock/switch rails are calculated based on the trace line method, and then the contact status is determined by the presented equations, finally, the distribution of wheel–rail contact forces of stock/switch rails is obtained based on the continuity of interface displacements and forces which using an approximate surface deformation method. Some parametric studies have been performed, such as the lateral displacement of wheel set, the vertical contact forces, the wheel profiles and the vertical stiffness of rail pad. The results of the parametric study are presented and discussed.     

基于有限元的路基振动压实动力学响应研究

基于ABAQUS软件，建立“振动轮-土体”三维有限元模型，采用扩展线性DruckerPrager模型和三维一致黏弹性人工边界方法，对轮下土体的应力、接触力等振动响应进行分析，研究振动压实过程中轮土的相互作用及由此产生的动力学响应。结果表明：沿振动轮横向，在振动轮边缘处土体竖向应力会发生严重衰减，据此可确定振动轮的碾压重叠宽度；沿压实路径纵向，竖向应力的中心点位于振动轮质心点前方，这是由于轮土接触面倾斜所导致的；根据节点接触应力的时程曲线可以计算总接地宽度，但总宽度之中大约只有1/3可以产生有效压缩变形。     

Modelling,validation and analysis of a three-dimensional railway vehicle–track system model with linear and nonlinear track properties in the presence of wheel flats

This paper presents dynamic contact loads at wheel–rail contact point in a three-dimensional railway vehicle–track model as well as dynamic response at vehicle–track component levels in the presence of wheel flats. The 17-degrees of freedom lumped mass vehicle is modelled as a full car body, two bogies and four wheelsets, whereas the railway track is modelled as two parallel Timoshenko beams periodically supported by lumped masses representing the sleepers. The rail beam is also supported by nonlinear spring and damper elements representing the railpad and ballast. In order to ensure the interactions between the railpads, a shear parameter beneath the rail beams has also been considered into the model. The wheel–rail contact is modelled using nonlinear Hertzian contact theory. In order to solve the coupled partial and ordinary differential equations of the vehicle–track system, modal analysis method is employed. Idealised Haversine wheel flats with the rounded corner are included in the wheel–rail contact model. The developed model is validated with the existing measured and analytical data available in the literature. The nonlinear model is then employed to investigate the wheel–rail impact forces that arise in the wheel–rail interface due to the presence of wheel flats. The validated model is further employed to investigate the dynamic responses of vehicle and track components in terms of displacement, velocity, and acceleration in the presence of single wheel flat.     

沥青混合料高温稳定性评价指标的试验研究

通过大量的室内试验,对沥青混合料高温性能的4种评价指标(动稳定度、车辙试验相对变形、单轴蠕变试验劲度模量、Superpave混合料最大次数下的残余空隙率)进行了比较分析。研究表明,采用不同评价指标来评价沥青混合料的高温性能,其基本规律是一致的;车辙试验的相对变形指标比较直观、准确;单轴蠕变试验与SHRP Superpave混合料高温性能的评价方法较为接近。车辙动稳定度指标有一定的局限性,建议采用其他3项指标来评价沥青混合料的高温性能。     

Wheel/Rail Non-linear Interactions With Coupling Between Vertical and Lateral Directions

Summary A theoretical model is developed to explore the high frequency wheel/rail interaction with coupling between the vertical and lateral directions. This coupling is introduced through the track dynamics due to the offset of the wheel/rail contact point from the rail centre line. Equivalent models of the railway track in the time domain are developed according to the rail vibration receptances in the frequency domain. The wheel is represented by a mass in each direction with no vertical-lateral coupling. The vertical wheel/rail interaction is generated through a non-linear Hertzian contact stiffness, allowing for the possibility of loss of contact between the wheel and rail. The lateral interaction is represented by a contact spring and a creep force damper in series and their values depend on the vertical contact force. The vibration source is the roughness on the wheel and rail contact surfaces which forms a relative displacement excitation in the vertical direction. Using the combined interaction model with this relative displacement excitation, the wheel/rail interactions with coupling between the vertical and lateral vibrations are simulated. It is found that the lateral interaction force caused by the offset is usually less than thirty percent of the vertical dynamic force. The lateral vibration of the rail is significantly reduced due to the presence of the lateral coupling, whereas the vertical interaction is almost unaffected by the lateral force.     

基于制动轨迹检测的汽车路试模拟技术

为提高汽车制动性能检测结果的客观性,解决对同一辆汽车进行台试与路试的检测结果不一致的问题,提出路试模拟技术.该技术得以实现的关键是汽车制动轨迹的检测,具体方法是:在单个矩形测试平板的4个角,分别安装相同的压力传感器,以矩形平板的相邻边,建立平面坐标系,当车轮在平板上制动时,利用力矩平衡原理,求得车轮制动时的运动轨迹.将测试平板并排串联放置,组成路试模拟系统,可以对汽车各个车轮的制动轨迹同时进行检测.利用该方法可实现对汽车制动距离、横向位移、航向角等参数进行实时检测,从而模拟路试法进行汽车制动性能的评价.     

独立悬架车辆转向轮侧滑及其影响因素的试验研究

结合独立悬架车辆转向轮定位参数的特点,采用二元二次回归正交组合设计方法设计了试验方案,并对影响转向轮侧滑的轮胎胎压、载荷和车速等相关因素进行了试验研究。通过对试验数据进行回归处理,得到了侧滑量与转向轮定位参数间的定量映射关系,并对其进行了回归系数、回归方程的显著性检验和失拟检验。结合汽车动力学相关理论对试验研究结果进行了分析。     

摩托车轻合金车轮径向冲击试验数据分析

摩托车轻合金车轮质量的好坏直接关系到摩托车骑乘者的人身安全,而摩托车轻合金车轮的径向冲击试验结果直接反映了车轮质量的优劣。通过对车轮径向冲击试验数据进行分析,以对车轮额定载荷的设定提出建议,希望摩托车整车企业及车轮生产企业合理设计轻合金车轮的额定载荷。