Numerical Prediction of Ride Comfort of Tracked Vehicle Equipped with Novel Flexible Road Wheels

Enhancing ride comfort has always constituted a crucial focus in the design and research of modern tracked vehicles,heavily reliant on the driving system's performance.While the road wheel is a key component of the driving system,traditional road wheels predominantly adopt a solid structure,exhibiting subpar adhesion performance and damping effects,thereby falling short of meeting the demands for high-speed,stable,and long-distance driving in tracked vehicles.Addressing this issue,this paper proposes a novel type of flexible road wheel(FRW)characterized by a catenary construction.The study investigates the ride comfort of tracked vehicles equipped with flexible road wheels by integrating finite element and vehicle dynamic.First,three-dimensional(3D)finite element(FE)models of both flexible and rigid road wheels are established,considering material and contact nonlinearities.These models are validated through a wheel radial loading test.Based on the validated FE model,the paper uncovers the relationship between load and radial deformation of the road wheel,forming the basis for a nonlinear mathematical model.Subsequently,a half-car model of a tracked vehicle with seven degrees of freedom is established using Newton's second law.A random road model,considering the track effect and employing white noise,is constructed.The study concludes by examining the ride comfort of tracked vehicles equipped with flexible and rigid road wheels under various speeds and road grades.The results demonstrate that,in comparison to the rigid road wheel(RRW),the flexible road wheel enhances the ride comfort of tracked vehicles on randomly uneven roads.This research provides a theoretical foundation for the implementation of flexible road wheels in tracked vehicles.

Annoyance Rate Evaluation Method on Ride Comfort of Vehicle Suspension System

The existing researches of the evaluation method of ride comfort of vehicle mainly focus on the level of human feelings to vibration. The level of human feelings to vibration is influenced by many factors, however, the ride comfort according to the common principle of probability and statistics and simple binary logic is tmable to reflect these uncertainties. The random fuzzy evaluation model from people subjective response to vibration is adopted in the paper, these uncertainties are analyzed from the angle of psychological physics. Discussing the traditional evaluation of ride comfort during vehicle vibration, a fuzzily random evaluation model on the basis of annoyance rate is proposed for the human body＇s subjective response to vibration, with relevant fuzzy membership function and probability distribution given. A half-car four degrees of freedom suspension vibration model is described, subject to irregular excitations from the road surface, with the aid of software Matlab/Simulink. A new kind of evaluation method for ride comfort of vehicles is proposed in the paper, i.e., the annoyance rate evaluation method. The genetic algorithm and neural network control theory are used to control the system. Simulation results are obtained, such as the comparison of comfort reaction to vibration environments between before and after control, relationship of annoyance rate to vibration frequency and weighted acceleration, based on ISO 2631 / 1 （1982）, ISO 2631-1 （1997） and annoyance rate evaluation method, respectively. Simulated assessment results indicate that the proposed active suspension systems prove to be effective in the vibration isolation of the suspension system, and the subjective response of human being can be promoted from very uncomfortable to a little uncomfortable. Furthermore, the novel evaluation method based on annoyance rate can further estimate quantitatively the number of passengers who feel discomfort due to vibration. A new analysis method of vehicle comfort is presented.

Vehicle Ride Comfort Based on Matching Suspension System

The existing investigations of vehicle ride comfort mainly include motion characteristics analysis based on creating a multi-body dynamic simulation model,and the parameters analysis to improve the suspension control for the target.In the study of creating multi-body dynamics simulation models,there is usually without considering calibration and test verification,which make it difficult to ensure the production of engineering.In the study of improving the suspension control parameters for the target,there is a lack of systematic match about comfortable and human characteristics,so it is difficult to implement in the field of driving and leading the vehicle design.In this paper,based on the different characteristic of suspension system that effects on the vehicle ride comfort, according to the suspension system dynamic mechanism,the research methods of vehicle road test,bench test and CAE simulation is used,at the same time,several sensitivity analysis of vehicle ride comfort related to suspension stiffness and damping and speed is made. As a result,the key suspension systematic parameters are given that have important impact on vehicle ride comfort.Through matching parameters,a calibration analysis of suspension system based on human comfort is obtained.The analysis results show that the analysis methods for the design target of making the vehicle with best comfort are effective.On the basis of the theory study,five suspension parameter matching principles are explored to promise the vehicle with perfect ride comfort,which also provide theoretical basis and design methods for the passenger car best match of suspension system stiffness and damping.The research results have the promotional value of practicability and a wide range of engineering application.

Ride comfort evaluation for road vehicle based on rigid-flexible coupling multibody dynamics

In the present research two different whole vehicle multibody models are established respectively, including rigid and rigid-flexible coupling multibody vehicle models. The former is all composed by rigid bodies while in the later model, the flexible rear suspension is built based on the finite element method （FEM） and mode superposition method, in which the deformations of the components are considered. The ride simulations with different speeds are carried out on a 3D digitalized road, and the weighted root mean square （RMS） of accelerations on the seat surface,backrest and at the feet are calculated. The comparison between the responses of the rigid and rigid-flexible coupling multibody models shows that the flexibility of the vehicle parts significantly affects the accelerations at each position, and it is necessary to take the flexibility effects into account for the assessment of ride comfort. C 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi： 10.1063/2.1301304]

Experimental Study on the Ride Comfort of a Crawler Power Chassis Scale Model Based on the Similitude Theory

The ride comfort experimental assessment of crawler off-road vehicle is relatively overlooked, and is expensive and difficult to execute with higher and higher ride comfort performance requirements. To trade off between precise and cost, an experimental method based on the similitude theory is proposed. Under the guidance of the similitude theory, a 1：5 crawler power chassis scale model equipped with a kind of variable stiffness suspension system is used. The power spectrum density（PSD）, the root mean square（RMS） of weighed acceleration, peak factor, average absorbed power（AAP） and vibration dose value（VDV） are selected as ride comfort evaluation indexes, and tests results are transformed via similarity indexes to predict the performance of full-scale power chassis. PSD shows that the low-order natural frequency of the vertical natural frequency（z axis） is 1.1 Hz, and the RMS, AAP and VDV values indicate the ride comfort performance of this kind of power chassis is between the ＂A little uncomfortable＂ and ＂Rather uncomfortable＂. From the results, low-order vertical natural frequency, obtained by PSD, validates that the similarity relationship between two models is satisfied, and 1：5 scale model used in experiment meets the similarity relationship with the full-scale model; consequently, the ride comfort prophase evaluation with the 1：5 scale model is feasible. The attempt of applying the similitude theory to crawler vehicle ride comfort test study decreases the cost and improves the test feasibility with sufficient test precise.

Frequency Weighting Filter Design for Automotive Ride Comfort Evaluation

Few study gives guidance to design weighting filters according to the frequency weighting factors,and the additional evaluation method of automotive ride comfort is not made good use of in some countries.Based on the regularities of the weighting factors,a method is proposed and the vertical and horizontal weighting filters are developed.The whole frequency range is divided several times into two parts with respective regularity.For each division,a parallel filter constituted by a low-and a high-pass filter with the same cutoff frequency and the quality factor is utilized to achieve section factors.The cascading of these parallel filters obtains entire factors.These filters own a high order.But,low order filters are preferred in some applications.The bilinear transformation method and the least P-norm optimal infinite impulse response（IIR） filter design method are employed to develop low order filters to approximate the weightings in the standard.In addition,with the window method,the linear phase finite impulse response（FIR） filter is designed to keep the signal from distorting and to obtain the staircase weighting.For the same case,the traditional method produces 0.330 7 m · s^–2 weighted root mean square（r.m.s.） acceleration and the filtering method gives 0.311 9 m · s^–2 r.m.s.The fourth order filter for approximation of vertical weighting obtains 0.313 9 m · s^–2 r.m.s.Crest factors of the acceleration signal weighted by the weighting filter and the fourth order filter are 3.002 7 and 3.011 1,respectively.This paper proposes several methods to design frequency weighting filters for automotive ride comfort evaluation,and these developed weighting filters are effective.

Effect of the off-road terrains on the ride comfort of construction vehicles

In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based on Matlab/Simulink software.The weighted root mean square(RMS)acceleration responses and the power spectral density(PSD)acceleration responses of the driver s seat heave,the pitch and roll angle of the cab in the low-frequency region are chosen as objective functions under different operation conditions of the vehicle.The results show that the impact of off-road terrains on the driver s ride comfort and health is clear under various conditions of deformable terrains and range of vehicle velocities.In particular,the driver s ride comfort is greatly affected by a soil terrain while the comfortable shake of the driver is strongly affected by a sand terrain.In addition,when the vehicle travels on a poor soil terrain in the frequency range below 4 Hz,more resonance peaks of acceleration PSD responses occurred than that on a rigid road of ISO 2631-1 level C.Thus,the driver s health is significantly affected by the deformable terrain in a low-frequency range.

Prediction Research on Ride Comfort of Special Full Trailer used by Precision Equipment

In order to evaluate a full trailer’s vibration performance,lumped mass model of seven degrees of freedom is set up to predict the ride comfort of whole vehicle.The acceleration history and the transfer function of each measuring point can be got from simulation.The analysis results show that the maximum acceleration RMS value of the vehicle mass center is about 0.3g,which satisfies the requirements of attenuating vibration of precision equipment being transported on particular roads and speeds.So the research provides valuable reference for the optimum selection of the suspension system’s parameters.

Automotive Ride Comfort Control Using MR Fluid Damper

In this paper, the performance of automotive ride comfort using Bouc-Wen type magneto-rheological (MR) fluid damper is studied using a two degree of freedom quarter car model. The sliding mode control is used to force the MR damper to follow the dynamics of ideal sky-hock model. The model is tested on two excitations, the first is a road hump with severe peak amplitude and the second is a statistical random road. The results are generated and presented in time and frequency domains using Matlab/Simulink software. Comparison with the fully active, ideal semi-active and conventional passive suspension systems are given as a root mean square values. Simulation results, for the designed controller, show that with the controllable MR damper has a significant improvement for the vehicle road holding then its lateral stability as well as road damage in comparison with passive, fully active and ideal semi-active suspension systems.

Research on Ride Comfort Model of Wheel Motor Driving Vehicle Based on Matlab/Simulink

Simulink is a visual simulation tool in MATLAB;?through Simulink software,?to establish a model can reduce the amount of programming workload,?and?improve the efficiency of the establishment of automotive models.?The ride comfort of the vehicle is a measure of the most basic indicators of a car performance.?By establishing a ride comfort model in Matlab/Simulink, the wheel motor electric vehicle mainly affects the smoothness of the car mainly in the following aspects:?pavement, tire, suspension, motor and so on.?Through the establishment of the above model,?we?can effectively study the wheel motor drive electric vehicle ride comfort research.

基于ADAMS/Car Ride汽车平顺性仿真

以多体动力学理论为基础,应用机械系统动力学仿真分析软件ADAMS/Car专业模块建立某轿车的整车样机模型。根据路面不平度位移功率谱密度推导路面随机激励数学模型,由路面轮廓发生器产生随机路面,并进行了随机路面输入下的汽车平顺性仿真。其研究结果为虚拟样机技术在车辆工程中的实际应用提供了参考,为进一步对实际车辆做其他设计分析打下了良好的基础。

高速列车主动垂向减振器多目标控制方法

以进一步提升高速列车的运行平稳性和曲线通过速度为目标,设计了转向架二系垂向减振器主动悬挂控制构型,提出了基于扰动观测器的滑模控制方法,实现了车体垂向振动和主动倾摆的多目标协同控制.建立车辆垂向简化动力学模型,设计兼顾车体浮沉、点头和侧滚模态振动的滑模面,基于滑模控制原理推导了主动力表达式;构建扰动观测器实现部分状态反馈量的估计,并证明控制系统的稳定性;进而,基于SIMPACK搭建车辆全自由度动力学模型,在MATLAB/SIMULINK中建立控制器和主动执行机构,实现动力学与控制联合仿真;分析主动倾摆控制效果,以及典型轨道不平顺激励下车体振动抑制效果.研究表明:所设计的主动垂向悬挂构型和滑模控制方法,可以显著降低车体10 Hz以内的垂向加速度和平稳性指标,优于传统天棚阻尼控制和被动悬挂工况;利用滑模控制还可实现曲线线路上车体主动倾摆,能够降低离心力对旅客乘坐舒适性的影响,可达到摆式列车的作用效果;车体主动倾摆控制会略微增大脱轨系数等安全性指标,但仍在安全限值范围内并具有足够裕量.主动垂减控制可以同时兼顾车体垂向振动与倾摆控制,进一步提升高速列车在直线和曲线线路上运行平稳性.

电动汽车电液复合制动系统平顺性控制研究

为减小电液复合制动系统制动模式切换时的整车冲击以及制动力波动,以前后双电机驱动电动汽车为研究对象,提出一种电液复合制动控制策略,包含轮缸压力跟随控制策略和电机补偿控制策略。轮缸压力跟随控制策略在液压制动介入时,利用H_(∞)鲁棒控制使液压制动系统能快速精确地控制制动力大小,保证制动系统的稳定性控制。电机补偿控制策略在液压制动与再生制动介入或撤出时,利用基于模糊PID的电机补偿控制策略减少复合制动系统因系统响应差异带来的冲击问题,提高制动舒适性。通过Simulink-AMESim-CarSim联合仿真平台进行仿真验证,结果表明,液压制动系统能快速精确跟随目标制动力,同时,制动力波动较无控制情况减小了90%,冲击度减小74%,显著提高了制动平顺性。

基于TruckSim的橡胶悬架载货汽车性能研究

文章结合载货汽车空满载载荷变化大的特点,建立橡胶悬架力学模型,通过台架试验验证了橡胶悬架非线性的力学特性。进一步将台架试验输出的刚度特性数据输入TruckSim,完成某8×4载货车TruckSim虚拟仿真模型建立,最后在TruckSim分别完成B级路面的整车平顺性仿真、稳态回转仿真、蛇形试验仿真。仿真试验结果表明,装备橡胶悬架的车辆平顺性、整车稳定性均能满足设计要求。

基于ADAMS/Car Ride负载隔离式电动车平顺性研究

针对新开发的负载隔离式电动车,本文利用多体系统动力学软件ADAMS/Car Ride,基于虚拟四柱试验台,建立了整车虚拟样机模型,同时按照《汽车平顺性试验方法》规定,建立随机输入路面和脉冲输入路面,对负载隔离式电动车进行不同车速下的平顺性仿真分析。仿真结果表明,当电动车分别以50,60,70,80,90km/h的车速在B级随机路面上行驶时,人体感受的加权加速度均方值分别为0.125,0.171,0.237,0.342,0.472m/s^2,乘客不会有不舒适感觉,当电动车以20,30,40km/h的车速行驶在脉冲输入路面时,座椅平面传递给乘客的最大加速度分别为8.04,8.40,8.74m/s^2,对乘客的健康没有危害。该方法可方便进行路面功率谱密度响应仿真试验,缩短了整车开发时间,改装后的负载隔离式电动车的平顺性满足要求。该研究为车辆的前期开发设计提供了理论依据。

某SUV车辆平顺性建模研究及其悬架参数优化

首先,利用多体动力学仿真软件ADAMS/View建立了某SUV车型的整车动力学模型。其次,开展了车辆平顺性实验,利用数据采集装置分别采集了车辆通过粗糙水泥路面及减速带时,车身沿纵向、横向及垂向的振动加速度信号,并通过车辆加速度振动响应验证了所建车辆模型的准确性。最后,基于ADAMS和isight的联合仿真技术,以提高车辆平顺性及稳定性为目标,采用多岛遗传算法对车辆前、后悬架刚度及阻尼进行多目标优化。优化后所得车辆悬架参数不仅能提高车辆平顺性,且有限改善了车辆行驶稳定性,较好解决了车辆行驶过程中平顺性及稳定性之间的矛盾。

基于刚柔耦合模型的多轴车辆平顺性仿真分析

针对采用一体化设计、整体式车身结构的多轴车辆,建立刚柔耦合虚拟样机模型,对多轴车辆的平顺性进行研究。基于驾驶室连接方式、驾驶室结构形式和驾驶室顶部连通形式3个设计要素,分析整车在不同载重和不同工况下的平顺性。分析表明,带有斜支撑桁架结构的驾驶室能够有效降低车辆行驶时驾驶室的加权加速度均方根值;顶部不连通的结构形式驾驶室舒适性更好;通过优化驾驶室结构形式和顶部连通形式,车辆在空载和满载情况下的平顺性得到了较大的改善,能够更好地满足使用要求。

实验教学用可调阻尼液压减振器的解析设计

现有可调阻尼减振器存在成本高、可靠性难保证等诸多缺陷,故汽车平顺性实验中常采用“更换不同被动阻尼减振器”方法测试阻尼对平顺性的影响,但此方法实验周期长、效率低且易造成减振器连接部件损坏。针对此问题,研制一种可调阻尼液压减振器,通过步进电机驱动芯杆与活塞杆相对转动调控节流孔而实现阻尼调节。提出基于汽车悬架系统最佳阻尼比的可调阻尼液压减振器解析设计方法,设计可调阻尼液压减振器的速度特性曲线、阻尼可调区域及阀系参数,并建立阻尼比、可调节流孔面积及步进电机转角间的函数关系。在此基础上,搭建样机并进行台架实验。结果表明:阻尼力实验值与要求值相对偏差小于2.0%,疲劳寿命是实验标准要求的2.1倍以上,表明此减振器满足性能和可靠性要求,说明所提可调阻尼液压减振器解析设计方法的有效性。此减振器用于汽车平顺性实验中可有效提高实验效率且避免减振器连接部件损坏,且可推广应用到减振特性实验及汽车半主动悬架实验等。

纯电动汽车脉冲激励下残余振动的多目标优化

利用Adams/Car软件建立某电机后置纯电动汽车的整车虚拟样机模型,并展开对电动汽车过坎冲击残余振动问题的研究。建立一个新的优化目标—振衰度来表示残余振动的大小,并利用Isight集成Adams/Car、MATLAB模块对残余振动进行两次优化目标不同的优化。首次优化目标是振衰度和后座椅垂向加速度峰值,第二次优化目标是后座椅垂向加速度峰值,并将两次优化结果作对比。仿真结果表明,首次优化目标对残余振动优化的效果好于第二次,说明新建的优化目标—“振衰度”能较好地衡量残余振动衰减速度的快慢,以此为优化目标对残余振动优化效果较好。

新型准零刚度空气悬架系统的设计与分析

为提高商用汽车在低频外部激励环境下的隔振性能以及行驶平顺性,基于准零刚度理论,采用正负刚度并联的方式,将负刚度碟形弹簧组与正刚度空气弹簧相结合,设计一种新型准零刚度悬架系统。通过静力学特性分析,建立力位移和刚度位移表达式,得到系统达到准零刚度的参数条件;通过动力学特性分析,建立系统的二自由度模型和简谐力作用下的非线性运动微分方程,得到力传递率特性曲线并对其进行分析。结果表明新结构的低频隔振性能显著提升。基于刚度位移表达式建立2自由度1/4悬架模型,分别对准零刚度系统与传统系统的垂向加速度、悬架动行程和轮胎动载荷等平顺性指标的差异性进行分析,仿真结果表明,该准零刚度系统的平顺性改善效果亦优于传统结构。