MotionView及HyperStudy在全地形车前悬架设计中的应用

为解决全地形车大行程前悬架的悬架跳动与前束角变化的协调问题,研究一款全地形车前悬架的运动学模型.在MotionView中建立该全地形车前悬架的运动学模型,借助HyperStudy对悬架跳动与前束角变化关系曲线进行优化,获得与理想曲线较接近的结果.     

影响汽车跑偏的因素

通过对汽车行驶跑偏的机理分析,并应用计算机仿真进行验证,对由于尺寸误差所引起的外倾角、前束角、主销拖距、主销偏置距、前后轴平行度等参数的变化对汽车行驶跑偏的影响进行深入的分析和探讨. 另外,整车质量的分布对汽车的行驶跑偏也有重要的影响.     

橡胶衬套刚度对悬架运动学的影响

橡胶衬套在现代汽车上的广泛应用对整车操纵稳定性和平顺性造成了很大的影响。为减少由于橡胶衬套引起的悬架运动学特性的变化,论文在ADAMS/View中建立了包含有橡胶衬套的麦弗逊悬架。通过ADAMS/Insight对各个衬套的刚度进行灵敏度分析,选取刚度变化对车轮定位参数影响较大的衬套刚度作为优化变量,以车轮前束角、外倾角和轮距作为优化目标。在Matlab中运用遗传算法调用ADAMS中的脚本文件,对橡胶衬套进行优化得到最优刚度值。经比较分析,优化后悬架定位参数变化范围减小。由此通过优化橡胶衬套刚度改善了悬架运动学特性。     

基于Adams/Car的汽车前悬架仿真分析及优化设计

针对某车型的麦弗逊前悬架系统,用车辆多体动力学仿真软件Adams/Car建立该悬架的虚拟样机模型,对其进行双轮同向跳动激振仿真分析,并综合评价该悬架的车轮定位参数、主销后倾拖距和转向角随轮跳的响应特性.在仿真分析的基础上,针对不合理的结构设计参数,利用Adams/Insight模块进行基于设计变量灵敏度分析的优化设计.优化后的悬架参数能很好地满足设计要求,从而达到提高该悬架系统整体性能的目的.     

橡胶衬套对后扭梁悬架性能的影响分析

在Adams/Car中建立后扭梁悬架模型,通过试验设计方法找出橡胶衬套各项刚度对悬架性能影响的贡献率,得出外倾角、前束角、悬架侧倾刚度及侧倾中心随衬套刚度的变化规律,最后选取影响悬架性能最大的刚度参数作为变量因子,对不同衬套刚度取不同的比例因子,通过Adams/Insight完成优化设计分析,并确定优化后的衬套刚度值.     

微型多功能车双横臂独立悬架优化设计

微型多功能车双横臂前独立悬架设计的好坏对车轮跳动时前轮前束和轮距的变化有很大的影响.运用虚拟样机技术,在ADAMS环境下建立了微型多功能车SX2526的前双横臂独立悬架刚-柔耦合模型,进行了运动学仿真.在此基础上运用"主要目标法"进行了以前轮前束和轮距变化为目标的悬架多目标优化设计,得到优化后的悬架空间结构的几何形式.经过悬架优化设计,前轮前束和轮距随车轮跳动时的变化范围大大减小.极大地改善了微型多功能车行驶过程中的操作稳定性.     

混合空气悬架系统侧倾仿真

为了研究某混合空气悬架的侧倾特性,在ADAMS/CAR中建立了该悬架系统刚柔体耦合的动力学模型。首先确定该型混合空气悬架的常用车轮跳动行程和台架侧倾仿真实验方法,然后确定了安装横向稳定杆和拆除横向稳定杆两种系统状态作为仿真工况,最后使用ADAMS/CAR,完成了该悬架系统在常用车轮跳动行程范围的台架侧倾仿真,得出了悬架侧倾刚度与车轮跳动关系曲线,探讨了横向稳定杆对该型悬架侧倾稳定性的影响结果。这个台架侧倾仿真模型可以用于确定该混合空气悬架系统在不同系统状态下的侧倾特性,校验悬架系统设计。     

某轿车的前双横臂独立悬架优化设计

研究某一轿车双横臂独立悬架性能的优化问题,解决前轮定位参数在汽车行驶过程中变化过大而引起的轮胎磨损的加剧以及悬架性能的降低的问题.针对上述问题,在ADAMS/Car上建立了车双横臂独立悬架的动力学模型,运用Insight模块进行灵敏度分析,选取灵敏度较大的硬点参数作为设计变量,建立车轮定位参数在轮跳过程中的最大变化量的响应面近似模型.然后运用差分进化算法与非支配遗传算法的混合多目标算法(简称DE-NSGAII算法)对目标函数进行优化求解.结果表明,优化后的车轮定位参数在车轮跳动过程中的变化量明显减小,悬架的性能得到改善,为悬架的优化设计提供了依据.     

双横臂独立悬架运动特性分析与优化

研究双横臂独立悬架性能优化问题,在车辆运动过程中,由于车轮与车身之间的相对位置发生变化,造成车轮定位参数的变动过大,加剧轮胎磨损,并降低悬架的性能.针对上述问题,通过对悬架系统简化处理,建立悬架运动学分析理论模型.为改进悬架性能,采用统一目标法,将多目标优化转化为单目标优化,实现在ADAMS/Insight中对悬架结构参数进行优化设计.利用ADAMS/Car软件建立了双横臂独立悬架动力学仿真模型并进行仿真,结果表明优化后车轮定位参数和轮距的变化量均减小,更趋于合理的取值范围,悬架性能得到改善.     

汽车转向机构仿真及优化设计

研究汽车转向机构优化设计问题,传统转向机构设计忽略转向机构与悬架干涉,造成实际工况下前轮定位参数变化过大,导致操纵稳定性下降.为了提高实际工况下转向性能,针对原地转向及车轮跳动工况,根据阿克曼转角几何原理及前轮定位参数变化规律,采用多目标优化方法建立复合加权惩罚函数进行优化设计.并在建立优化模型时引入试验设计方法(DOE)进行设计变量筛选.应用ADAMS软件建立某车前悬架总成动力学模型进行仿真优化.仿真结果表明,优化后模型更好地满足了阿克曼转角几何原理,转向机构与悬架更加匹配,验证了改进方法在转向机构优化设计中的实用性与优越性.     

Modelling of Torsion Beam Rear Suspension by Using Multibody Method

The multibody systems analysis has become one of the main simulation techniques to calculate the elasto-kinematics characteristics of a car suspension under wheel loads or to realize complex full vehicle models in order to predict the handling performances or the NVH quality. The modelling of torsion beam rear suspensions—widely adopted in cars belonging to B or C class—presents some problems arising from the structural behaviour of this component. A linear method based on component mode synthesis was used to represent the flexible torsion beam within the multibody model. This kind of approach was compared with a non-linear FE analysis. The elasto-kinematics analysis of the suspension was performed by using SIMPACK multibody code. The main suspension parameters (toe angle, camber angle, wheelbase and track variation) were calculated by changing wheel travel and loads. Static analyses, involving great displacements, were performed and a different number of modes were considered in the modal condensation of the torsion beam. The results of multibody simulations were compared with those obtained from a non-linear FE model. Different stiffness values of the bushings that connect the torsion beam to the vehicle chassis were taken into account.     

麦弗逊前悬架的刚柔耦合模型仿真及优化分析

在Adams/Car环境中建立某车麦弗逊前悬架的多刚体模型和刚柔耦合模型,分别对其进行双轮同向激振仿真,分析车轮定位参数的变化规律. 结果证明刚柔耦合模型和多刚体模型分析结果基本一致.针对车轮定位参数变化规律的不合理性,利用Adams/Insight对悬架部分硬点进行灵敏度分析并优化硬点坐标,使车轮定位参数在一定的范围内变化,改善悬架的性能.     

非独立悬架车辆自激摆振的数值仿真分析

基于一个三自由度的转向系统模型,利用数值仿真方法分析了横拉杆刚度、主销后倾角、转向机刚度、轮胎侧偏刚度、轮胎拖距、转向机阻尼、绕主销当量阻尼等参数对载重汽车自激型摆振的影响.仿真分析的结果表明,上述参数发生变化时,可诱发自激摆振,但车速也是影响摆振的关键因素之一.在确定的系统参数和车速下,初始激励不仅可能诱发稳定的自激摆振,还可能是发散的运动.与受迫型自激摆振不同,自激型摆振的频率变化与车速的变化并不一致.     

前梁对汽车前轮摆振的影响分析及仿真研究

某重型车在行驶时常出现前轮摆振现象,为此对前梁进行了建模和仿真分析.首先使用Pro/E建立前梁模型;接着使用Pro/M对其进行静态分析,分析了车辆直线行驶和转弯行驶时前梁的变形情况,并对前梁进行了模态分析,得到其前8阶固有频率和振型,通过振型分析了前梁的动态性能;最后使用SIMULINK模块仿真分析了前梁在B级路面上速度为50km/h时由路面不平度引起的随机振动.结果表明:满载行驶时,前梁在路面不平度的激励下产生的垂直位移满足行业标准,固有频率远离路面不平度激励下的频率,不会产生共振而导致摆振.但是转弯时前梁主销偏移距过大易引起前轮摆振,应适当减小其内倾角角度来避免转弯时摆振的发生.     

Nonlinear analysis and control of a variable-geometry suspension system

The paper proposes methods for both the analysis and the synthesis of variable-geometry suspension systems. The nonlinear polynomial Sum-of-Squares (SOS) programming method is applied in the analysis and it gives the optimal utilization of the maximum control forces on the tires. Moreover, the construction of the system can be based on the nonlinear analysis. The variable-geometry suspension system affects the wheel camber angle and generates an additional steering angle, thus the coordination of steering and wheel tilting can be handled. An LPV (Linear Parameter-Varying) based control-oriented modeling and control design for lateral vehicle dynamics are also proposed. The novelty of the method is the combination of the LPV-based control design and the SOS-based invariant set analysis. The simulation example presents the efficiency of the variable-geometry suspension system and it shows that the system is suitable to be used as a driver assistance system. In the SIL (software-in-the-loop) simulation both the dSPACE-AutoBox hardware and the CarSim simulator are used as standard industrial tools.     

Design,fabrication and testing of a novel symmetrical 3-DOF large-stroke parallel micro/nano-positioning stage

Limited travel stroke constrains the application of existing XYZ parallel micro/nano-positioning stages. In this paper, a novel parallel-kinematic symmetrical micro/nano-positioning stage is proposed to enlarge the travel range with a compact physical size. For a large-stroke parallel stage, the cross-axis motion increases the difficulty of closed-loop control process. The motions of the parallel stage on different axes are decoupled by employing I-shaped flexure hinges in this work. In order to obtain a large input displacement for actuating the stage, three voice coil motors (VCM) are adopted. In view of the lower output force of the VCM, the guiding flexure mechanism is designed with an optimized cross-sectional dimension. To verify the performance of the stage, analytical modeling and simulation study are carried out. A prototype stage is fabricated for experimental studies. Results show that the designed parallel micro/nano-positioning stage owns a three-degree-of-freedom motion workspace of 2.22 mm × 2.22 mm × 1.81 mm with an overall size of 176 mm × 176 mm × 198 mm, which is more compact than existing symmetrical designs containing the actuators. Moreover, the symmetrical design enables a low crosstalk of 1.7% among the three working axes.