The Wheel Shimmy Problem: Its Relationship to Wheel and Road Irregularities

SUMMARY

The equations of motion are derived for a single wheel steerable pneumatic tire system. Included in this system are a built-in wheel wobble and wheel-tire irregularities which produce oscillation of the normal load. Special emphasis is placed on the dynamic characterization of the tire cornering force and aligning torque. The results show that the built-in wheel wobble causes a steady shimmy which is large when the wheel rotation frequency is close to the natural shimmy frequency. The results also show that a normal load oscillation which has a frequency approximately twice the natural shimmy frequency causes a decrease in shimmy stability.     

A Comparison of Tyre Representations in a Simple Wheel Shimmy Problem

A simple system capable of wheel shimmy is analysed in three different ways and the results are compared. The tyre in each case is taken to be representable by a “taut string”, and the three ways involve (a) developing a digital tyre simulation which operates sequentially with a digital simulation of the mechanical system, (b) representing the tyre responses by linear constant coefficient differential equations derived empirically to match the string responses, and (c) as in (b) but employing fundamentally derived equations which approximate the exact string responses. The approximations are shown to give good results at reduced frequencies typical of the wheel shimmy phenomenon.     

EQ2102型越野车前轮摆振问题的研究

从前轮摆振的一般概念入手,阐明了前轮摆振问题的形成机理、技术对策,结合EQ2102型越野车的前轮摆振实际。深入分析了该问题产生的原因,系统地提出了工艺、产品等方面的解决方案,并获得了良好的实际效果。     

轻型客车方向盘摆振原因分析及解决措施

对某轻型客车高速行驶时方向盘摆振的原因进行分析,并寻找其激励源和传递路径,最后提出解决措施.     

汽车操纵稳定性与前轮摆振的非线性仿真分析

以某轿车为例,建立3自由度整车系统动力学模型,利用常微分方程稳定性理论和数值仿真计算,详细研究整车的稳态转向特性和系统失稳后的前轮摆振特性。阐明汽车的操纵稳定性与前轮摆振特性同属汽车整车稳定性问题,前者是负刚度系统,后者是负阻尼系统。在一定的参数组合下,具有不同转向特性的汽车都或多或少地存在摆振现象,这与实际情况相符,建议适当增加转向系阻尼和刚度以减小甚至消除摆振的发生。     

某大客车转向轮摆振及影响因素的分析

考虑侧偏角和侧偏力之间的非线性关系,建立4自由度某大客车转向轮摆振模型。运用非线性动力学理论,确定转向轮发生自激摆振的Hopf分岔点：通过MATLAB＆Simulink软件建立大客车转向轮摆振仿真模型。通过仿真结果检验理论分析,并得到车速、转向系参数、横拉杆参数、质心位置、主销后倾角与转向轮自激摆振幅值或频率的关系曲线．找出影响自激摆振的敏感参数及敏感参数的适取范围,能有效减小或消除客车的自激摆振。     

关于车辆方向盘摆振的补偿方法及补偿系统研究

研究电动助力转向系统对方向盘摆振补偿的功能,通过对影响方向盘摆振因素的分解,当整车基本参数确定的情况下可以采用EPS进行摆振补偿.通过摆振补偿功能开发到某车型实车测试验证,有效解决高速制动等工况下方向盘摆振问题.该研究为车辆方向盘摆振问题的解决提供采用EPS补偿万式提供方法及系统.     

转向柱后倾角对三轮汽车前轮自激摆振特性影响

为获得转向柱后倾角对三轮汽车摆振影响,以国产某型三轮汽车作为样车,对其转向系统进行了简化,建立了二自由度前轮摆振系统动力学模型。基于以上模型,运用数值计算方法,得到了随车速变化的前轮摆振系统振动特性及转向柱后倾角变化对其的影响。结果表明,减小转向柱后倾角,能有效减小三轮汽车前轮自激摆振的速度区间。而当车速较高,前轮摆振系统发生自激振动时,减小转向柱后倾角能有效地降低前轮自激摆振极限环幅值和频率,甚至消除自激摆振现象。     

EQ2102越野汽车前轮摆振影响因素试验分析及改进措施

针对东风EQ2102型独立悬架越野汽车的前轮摆振问题进行了道路试验分析,研究了前轮失衡量、转向系统阻尼和刚度对前轮摆振的影响。试验及分析表明,该车摆振主要为强迫振动,通过控制激振源、增大转向系统阻尼可抑制摆振。提出了采用阻尼轴承代替主销滚针轴承来增大转向阻尼的解决方案,同时评估了阻尼轴承对汽车操纵稳定性的影响。     

超越对手超越自我——记东风德纳重型轮边减速桥的自主开发之路

重型轮边减速桥是东风德纳车桥公司面对工程车领域,抓住大吨位高动力重型车需求迅猛增长之势,为适应超重载型的自卸车运输市场而开发的全新车桥。由于该公司秉承了东风汽车公司一贯的作风：全面为用户考虑,给用户的一定是成熟可靠的产品,为用户创造更大的价值,使该产品进入市场即受好评,订单纷至沓来。     

车轮轮胎总成的路障冲击试验

轮毂的性能直接影响汽车的行驶安全和乘客的人身安全,车轮轮胎总成的路障冲击试验对轮毂的性能有了更高的要求。文章通过从SAEJ1981标准的总体要求、试验范围及冲击方式等方面的介绍提供了引导开发新的车轮轮胎总成路障冲击试验的背景信息,表明SAEJ1981标准能公正地评估车轮和轮胎总成的路障冲击试验,指出国内在车轮新品验证过程和周期性试验中也应增加该冲击试验项目,以充分保障产品的安全性。     

车辆前轮摆振的原因分析与解决方法

简要介绍前轮摆振的现象;分析原因,并找出解决方法。     

Solution of the Multiple Wheel and Rail Contact Dynamic Problem

SUMMARY

An unconventional method for calculating the forces developing in the wheel and rail contact patches of a railway vehicle has been implemented at the New Technology Laboratory of INRETS. It takes into account the elastic deformations of the materials in the Hertzian elliptical contact areas; the possibility of having simultaneously several contact patches on each wheel, is introduced in the simulation of the dynamic phenomena.

The theory is applied for a high speed bogie running on a perfectly straight track.     

Solution of the Multiple Wheel and Rail Contact Dynamic Problem

An unconventional method for calculating the forces developing in the wheel and rail contact patches of a railway vehicle has been implemented at the New Technology Laboratory of INRETS. It takes into account the elastic deformations of the materials in the Hertzian elliptical contact areas; the possibility of having simultaneously several contact patches on each wheel, is introduced in the simulation of the dynamic phenomena.

The theory is applied for a high speed bogie running on a perfectly straight track.     

轮胎在水平路面上的自由滚动接触分析

利用轮胎的模态参数直接对轮胎在水平路面上的滚动建立了便于解析计算的仿真模型。该模型可模拟轮胎稳态的滚动过程并可计算出不小同工况下的滚动特性、有效滚动半径、载荷与下沉量的关系以及印迹内变形和分布力。计算结果揭示了以往模型难以描述的微观现象,与以往文献的试验研究结果定性一致,充分显示了模型的合理性。     

压路机钢轮破裂的原因分析与总结

通过分析戴纳派克CC322双钢轮压路机使用情况，阐述双钢轮压路机钢轮产生裂纹的原因及处理方法，总结机械设备全员、全过程管理的重要性和必要性。     

城市交通问题对路网规划的影响探讨

从城市可持续发展角度,分析了我国城市面临的主要交通与路网规划问题。以解决城市远期交通问题为目标,从路网规划的源头出发,采用科学的方法进行研究分析,提出若干合理有效的解决方案。同时建议制定城市道路规划建设的可持续交通发展战略,充分发挥城市交通全局性、先导性及基础性作用。     

VISSIM微观仿真系统及在道路交通中的应用

道路交通仿真是当前的热点研究课题之一。微观交通仿真软件系统VISSIM是目前世界上最先进、功能最完善的仿真系统。本文对其模块构成、功能及应用领域等进行了介绍,阐明了该系统的优越性．并建议加快引进和推广VISSIM系统在我国的应用。     

Simulation of the Interaction between Vehicle Wheel and the Unevenness of Road Surface

SUMMARY

A model of the relationship between a vehicle wheel and the unevenness of the road surface is defined. The wheel is considered to be of circular shape. For a given form of unevenness, the excitation functions are evaluated for the individual subsystems of the dynamic vehicle model having 5 degrees of freedom. The vehicle model traverses the uneven surface at a variable velocity. The model provides for the study of the complex dynamic phenomena which occur between the wheel and the unevenness. The response of the model also includes the dynamic stress on the drive when the wheel passes over the unevenness of the road surface.     

Simulation of the Interaction between Vehicle Wheel and the Unevenness of Road Surface

A model of the relationship between a vehicle wheel and the unevenness of the road surface is defined. The wheel is considered to be of circular shape. For a given form of unevenness, the excitation functions are evaluated for the individual subsystems of the dynamic vehicle model having 5 degrees of freedom. The vehicle model traverses the uneven surface at a variable velocity. The model provides for the study of the complex dynamic phenomena which occur between the wheel and the unevenness. The response of the model also includes the dynamic stress on the drive when the wheel passes over the unevenness of the road surface.