【作者】 路永婕；

【导师】 杨绍普；

【作者基本信息】 北京交通大学 ， 载运工具运用工程， 2011， 博士

【摘要】 摘要：目前公路交通朝着高速化、重载化的方向发展,车辆行驶平顺性、操纵稳定性、安全性和道路的早期破坏等问题引发人们广泛的关注。虽然研究人员很早就意识到车辆动态载荷对路面的破坏作用,但在路面实际设计方法中,对动载作用的考虑仅限于在静力计算基础上加以经验修正。研究车辆—路面相互作用机理的成果,将在优化重载汽车结构、改善路面使用性能和提高路面使用寿命等方面具有重要的理论意义和工程应用价值。本文针对车辆—路面系统,通过建模、理论分析、数值仿真、实验验证的技术路线,研究汽车与路面之间的相互作用的动力学,探讨路面早期破坏机理等。论文主要研究工作如下：(1)减振器与钢板弹簧是重载汽车悬架上关键的两个部件,其阻尼特性与刚度特性直接影响着车辆平顺性和道路友好性。在减振器实验中,通过对减振器进行稳态正弦位移激振和随机激振实验,得到在不同频率和不同行程下的阻尼特性曲线;在钢板弹簧实验中,通过逐级加载和卸载的方式得到钢板弹簧的刚度特性曲线。依据实验数据,分别建立减振器与钢板弹簧的非线性动力学模型。(2)提出“独立式平衡悬架”和“整体式平衡悬架”两种动力学模型,将这两种模型与四分之一重载汽车模型对比,发现四分之一车模型可评价车辆行驶的平顺性,但在评价车辆道路友好性方面存在局限性,且平衡悬架系统比单轴车更容易带来路面破坏。基于车体加速度和道路破坏系数,分析两种平衡悬架模型在各种车辆设计参数和运行参数下对车辆行驶平顺性和道路友好性的影响和差异。(3)建立具有平衡悬架的三轴重载汽车模型,计及悬架上减振器与钢板弹簧的非线性特性,同时结合具有包容特性的FRC(Flexible Roller Contact)轮胎模型,提出车辆—轮胎—路面耦合模型。模型还原了车辆—轮胎—路面之间相互作用过程,为车辆平顺性与道路友好性的研究提供新的研究思路。(4)基于多体动力学理论,建立刚、柔耦合的多体重载汽车模型,详细考虑车辆系统结构的几何参数、减振器的非线性特性、钢板弹簧的柔性和随机路面不平度等。通过现场实验,验证了整车动力学模型进行动载分析的有效性。基于可靠的汽车模型,应用试验设计方法,提出正交优化的方案,研究车辆悬架参数对该车平顺性和道路友好性的影响。通过多组样机虚拟实验和极差分析,找出最重要的影响因素,确定其取值范围,形成使得车辆平顺性和道路友好性最优的匹配方案。更多还原

【Abstract】 ABSTRACT:Nowdays high speed and heavy load are two kinds of main developing trends in highway transportation. Thus vehicle ride comfort, handling stability, safety and road early damage have caused widespread concern. Although researchers have already been aware of the effect of dynamic load on road damage, its role is limited to static load on the basis of experience amendment in actual pavement design. Thereofore the research on vehicle and road surface interaction has important theoretical meaning and engineering application value in optimizing heavy vehicle structure, improving service performance and service life of road.The main goal of this work is to research dynamics of interaction between heavy vehicle and road and to investigate road’s early damage by modeling, theoretical analysis, numerical simulation and experimental test. The main research work of this present dissertation is summarized as follows:Firstly, both shock absorber and leaf spring are key components of heavy vehicle suspension. The damping and stiffness characteristics have an important influence on vehicle ride comfort and road friendliness. The damping characteristics of shock absorber are tested under sinusoidal and random displacement excitation. The forve-velocity curves are obtained under different frequencies and different amplitudes. The stiffness curves of leaf springs are obtained through cascaded loading and unloading. Based on testing results, the nonlinear dynamic models of shock absorber and leaf springs are established, respectively.Secondly, two kinds of dynamics models of independent and integral balanced suspension models are proposed. The sprung mass acceleration and the tire dynamic forces for two kinds of balanced suspension and traditional quarter-vehicle model are compared in frequency and time domain, respectively. It is concluded that quarter-vehicle model could be used to evaluate the ride comfort of vehicle, but it indeed has some limitations in evaluating vehicle road friendliness. The sprung mass acceleration and road damage coefficients for balanced suspension are also analyzed under different vehicle design and running parameters.Thirdly, a tri-axle vehicle model with balanced suspension is modeled by considering the nonlinearity of shock absorber and leaf springs. Furthermore, a vehicle-tire-road coupling model is proposed by combing the enveloping FRC (Flexible Roller Contact) tire model and tri-axle vehicle model. The presented mathematic model could restore the interacting process of vehicle-tire-road system. It is expected that these works could supply a new idea for vehicle-road interaction research.Finally, a rigid-flexible coupling model of a heavy vehicle is built based on multi-body dynamics theory. The geometric parameters of the vehicle system, the nonlinear characteristics of shock absorber, the flexibility of leaf springs and the stochastic road surface are precisely described. The dynamic vehicle model is validated by testing data. According to the design of experiment (DOE) method, an orthogonal optimization program for valid vehicle model is presented to study the effect of vehicle parameters on ride comfort and road friendliness. After several virtual experiments and range analysis, the most important influencing factor and its range are screened out. Then a matching scheme is formed to make ride comfort and road friendliness optimization.更多还原