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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. 相似文献
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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。 相似文献
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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。 相似文献
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Nicolò Tomiati Alessandro Colombo Gianantonio Magnani 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2019,57(3):315-335
This paper presents a nonlinear model accurately describing, both qualitatively and quantitatively, the onset and dynamics of bicycle shimmy. Methods of nonlinear dynamics, such as numerical continuation and bifurcation analysis, show that the model exhibits two stable periodic motions found experimentally in on-road tests: the weave and wobble (or shimmy) mode. The modelling results are compared with experimental data collected by riding a racing bicycle downhill at high speeds with hands on the handlebar. The model predicts with surprising accuracy the amplitudes and frequencies of the oscillations, the longitudinal velocity at which they occur, as well as the substantial independence of wobble frequency and amplitude from the forward speed. The lateral acceleration of the upper tube of the frame near the steering axis reaches 5–10?g, both in the model and in the data. The analysis shows that wobble onset and amplitude is particularly sensitive to changes in the torsional stiffness of the frame and strongly depends on tyre lateral force and aligning torque at the wheel–road contact point. It also allows to quantify the additional viscous rotary damping that should be added to the steering assembly to prevent wobble. 相似文献
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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。 相似文献
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汽车操纵稳定性与前轮摆振的非线性仿真分析 总被引:3,自引:0,他引:3
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。 相似文献
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前轮定位参数对前轮摆振的影响是极其复杂的,它不仅影响了前轮的几何特性,并且对摆振系统的运动,约束与受力状况均产生重要影响。本文建立了包括全部前轮定位参数的前轮摆振数学模型;并在轮胎试验的基础上,比较系统、全面地研究了前轮定位参数对前轮摆振的影响规律。本文还研究了轮胎蛇形运动频率对汽车动力学摆振的影响。 相似文献
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EQ2102越野汽车前轮摆振影响因素试验分析及改进措施 总被引:1,自引:0,他引:1
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。 相似文献
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为了提升整车操纵稳定性和舒适性,采用理论分析和实车试验相结合的方法探讨了车轮偏心对转向盘摆振的影响。从理论上分析了车轮偏心引起的激振力和车轮动不平衡对转向盘摆振的贡献;以某B级车为研究对象,进行了多个因素的对比试验。结果表明:调整车轮动平衡对转向盘摆振稍有影响,调整下摆臂后衬套也有一定影响,但都不能明显减小振动加速度幅值;调整车轮偏心对转向盘摆振有显著影响,调整车轮偏心后,振动加速度幅值减小了近2倍;车轮偏心比动不平衡对转向盘摆振的影响更大,通过调整车轮安装定位方式消除安装偏心,对转向盘摆振现象的改进效果明显。 相似文献
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R. S. Sharp lecturer C. J. Jones research student 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1980,9(1):45-57
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. 相似文献
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Hans B. Pacejka 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1973,2(1):49-60
An improved approximation of the theory of the dynamic frequency response of side force and aligning torque acting upon the rolling wheel when the latter is moved laterally and swivelled about the vertical axis, is presented. The method is particularly suitable for application in vibration problems of steering and suspension systems of automobiles and aircraft where relatively high speed and high frequency phenomena play a role. The theoretical results show satisfactory agreement with experimental data. Calculations indicate that the inertia of the tire decreases the tendency to shimmy at higher frequencies and speeds of travel. For castered wheels however, tire inertia may have an adverse effect due to its unfavorable influence upon the side force response to swivel motions. 相似文献
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轮胎动态侧偏特性对汽车摆振的影响 总被引:7,自引:0,他引:7
轮胎的侧偏力学特性是影响汽车前轮摆振的最关键因素之一,文中在箕是汽车研究所提出了轮胎动态侧偏特性试验方法的基础上,建立了侧向力与回正力矩的精确表达式,并从能量反馈和负阻尼效应研究了轮胎动态侧偏特性参数对汽车偏摆振的影响。 相似文献
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轮胎非稳态转向特性非线性仿真模型 总被引:2,自引:1,他引:2
本文以轮与路面之间的滑移速度为出发点,在稳态指数统一模型的基础上,建立了轮胎非稳态转向特性非线性仿真模型。在实验研究中,发现了动态过程回正力臂和附加的回正力矩的滞后特性。仿真和试验结果对比表明,该模型足以反映轮胎非线性转向特性,可用于前轮及汽车操纵动力学仿真方面的研究。 相似文献
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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(3):415-429
Wheel shimmy and wobble are well-known dynamic phenomena at automobiles, aeroplanes and motorcycles. In particular, wobble at the motorcycle is an (unstable) eigenmode with oscillations of the wheel about the steering axis, and it is no surprise that unstable bicycle wobble is perceived unpleasant or may be dangerous, if not controlled by the rider in time. Basic research on wobble at motorcycles within the last decades has revealed a better understanding of the sudden onset of wobble, and the complex relations between parameters affecting wobble have been identified. These fundamental findings have been transferred to bicycles. As mass distribution and inertial properties, rider influence and lateral compliances of tyre and frame differ at bicycle and motorcycle, models to represent wobble at motorcycles have to prove themselves, when applied to bicycles. For that purpose numerical results are compared with measurements from test runs, and parametric influences on the stability of the wobble mode at bicycles have been evolved. All numerical analysis and measurements are based on a specific test bicycle equipped with steering angle sensor, wheel-speed sensor, global positioning system (GPS) 3-axis accelerometer, and 3-axis angular velocity gyroscopic sensor. 相似文献
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H.-P. Willumeit F. B hm 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1995,24(6):525-550
This paper presents a survey of the state-of-the-art in predicting the wheel vibrations in a complex dynamic vehicle suspension system and their influence on the forces transduced in a high frequency area from the tire to the vehicle's body. Secondly it presents also the transient evolution of tire models used for prediction and understanding high frequency movements in the tire's contact area, producing the guiding forces and torques during vehicle handling. 相似文献