3E轴构架转向架的通用动力学要求

为了更好地实现铁路货运的重载快捷发展目标,以双层集装箱车辆作为应用研究对象,利用刚柔耦合仿真分析手段进行了3E轴构架转向架100~135 km/h动力学性能分析.6轴双层集装箱车辆刚柔耦合分析表明：空载承载鞍滑动现象和重载中轴轮对稳定性将是其高速运营的主要性能问题.因而,确保空载轮对定位刚度、确保重载中轴轮对轮轨关系稳定和降低车体结构耦合振动响应水平应作为3轴构架转向架的通用动力学要求.为此,提出了如下三项技术对策：①1、3轴承载鞍应以45°倒面作为承载摩擦面,满足摩擦系数μe≥0.42,而中轴小承载鞍则以磨耗板进行减磨处理μ〈0.2;②以中轴轮对车轮轮缘减薄9 mm的LM修正踏面优化来提高轮轨匹配的等效锥度控制中轴轮对横移,进而降低转向架蛇行运动程度;③中轴轴箱增设斜楔摩擦减振以降低落下孔车体中部结构振动耦合响应.与原设计对比,该技术对策可以使车辆动态性能得到改善.     

最佳轮轨匹配评价5原则

为了更好地研究轨道车辆动力学性能,在四种典型踏面（S1002、S1002G、XP55和LMA）轮轨匹配特性对比分析基础上,提出了最佳轮轨匹配评价5原则.与锥形踏面相比,曲线型面踏面赋予了轮轨匹配新的内涵,如等效锥度是反映轮轨横向力对运行质量影响的等效平均参数.在充分考虑了轮背距、轨底坡和轮径等轮轨参数影响的条件下,四种踏面的轮轨匹配表明,LMA和XP55可以满足高速车辆的稳定性和轮轨低动力作用的要求,但是,在踏面磨耗方面尚存在不足：LMA的轮缘根部以单一曲率圆弧作为过渡段且存在接触综合曲率＂突变＂,有可能形成集中磨耗;而XP55在小半径R≤500 m曲线通过时牵引系数较高,有可能造成车轮打滑和轮缘接触.由于在轨道窗口内具有锥形踏面匹配特征,因而S1002被看作磨耗敏感型踏面.S1002G的改进设计意图是在轮背距1 353 mm和轨底坡1∶20的轮轨条件下进一步提高原S1002踏面的轮轨对中性能和导向性能,但需要利用抗蛇形减振器进一步提高其横向稳定性.根据国外轻轨车辆的运营经验,基于轮轨磨耗研究的＂通用＂轮轨型面方法是非常值得借鉴和研究的.     

便携式汽车车轮检测仪的研发

研制了一套便携式汽车车轮检测仪。根据车轮被测参数及性能指标要求,设计了检测仪机械部分总体方案和主要部件,并对机械部分进行了误差分析。实践证明,该检测仪能检测多品种多规格车轮的径、轴向跳动和压配深度(偏距)。     

复合式路面层间夹层抗反射裂缝能力的模拟试验

为了探索不同夹层材料对延缓旧水泥路面沥青加铺层整体结构反射裂缝的效果,在现有国内外防反射裂缝室内模拟试验的基础上,采用加载方式更接近于实际的轮辙仪进行模拟试验。对比研究了加铺经编玻纤格栅、FHGS高强玻纤复合材料土工格栅(简称FHGS格栅)、聚酯玻纤布和橡胶沥青应力吸收层等4种防反射裂缝措施与直接加铺沥青面层之间防反射裂缝效果的差距。试验结果表明:加铺经编玻纤格栅、FHGS格栅、聚酯玻纤布、橡胶沥青应力吸收层与无防反措施相比,其加铺层顶部初裂轮载作用次数分别提高了2.65,2.26,2.04,1.61倍;终裂轮载作用次数分别提高了4.34,3.97,3.31,2.61倍。考虑到尺寸效应的影响,在刚柔复合式路面的实际工程中应当优先采用FHGS格栅作为防反射裂缝的措施。     

车轮偏心对转向盘摆振的影响分析

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。     

基于Abaqus显式算法的铸铝车轮碰撞模拟

介绍了一种基于Abaqus显式算法的计算方案来预测车轮在按SAE J175的规定进行车轮冲击试验过程中的车轮碰撞性能.为节省计算时间,赋予碰撞体一个撞击初速度代表其自由下落过程的最终状态,并采用了质量缩放法.以等效塑性应变作为损坏指标判定车轮是否通过动态冲击测试标准.仿真结果得到实例的验证,并表明车轮的塑性变形主要集中...     

Nonlinear PI front and rear steering control in four wheel steering vehicles

Vehicle steering dynamics show resonances, which depend on the longitudinal speed, unstable equilibrium points and limited stability regions depending on the constant steering wheel angle, longitudinal speed and car parameters.

The main contribution of this paper is to show that a combined decentralized proportional active front steering control and proportional-integral active rear steering control from the yaw rate tracking error can assign the eigenvalues of the linearised single track steering dynamics, without lateral speed measurements, using a standard single track car model with nonlinear tire characteristics and a non-linear first-order reference model for the yaw rate dynamics driven by the driver steering wheel input. By choosing a suitable nonlinear reference model it is shown that the responses to driver step inputs tend to zero (or reduced) lateral speed for any value of longitudinal speed: in this case the resulting controlled vehicle static gain from driver input to yaw rate differs from the uncontrolled one at higher speed. The closed loop system shows the advantages of both active front and rear steering control: higher controllability, enlarged bandwidth for the yaw rate dynamics, suppressed resonances, new stable cornering manoeuvres, enlarged stability regions, reduced lateral speed and improved manoeuvrability; in addition comfort is improved since the phase lag between lateral acceleration and yaw rate is reduced.

For the designed control law a robustness analysis is presented with respect to system failures, driver step inputs and critical car parameters such as mass, moment of inertia and front and rear cornering stiffness coefficients. Several simulations are carried out on a higher order experimentally validated nonlinear dynamical model to confirm the analysis and to explore the robustness with respect to unmodelled dynamics.     

Vehicle systems: coupled and interactive dynamics analysis

This article formulates a new direction in vehicle dynamics, described as coupled and interactive vehicle system dynamics. Formalised procedures and analysis of case studies are presented.

An analytical consideration, which explains the physics of coupled system dynamics and its consequences for dynamics of a vehicle, is given for several sets of systems including: (i) driveline and suspension of a 6×6 truck, (ii) a brake mechanism and a limited slip differential of a drive axle and (iii) a 4×4 vehicle steering system and driveline system.

The article introduces a formal procedure to turn coupled system dynamics into interactive dynamics of systems. A new research direction in interactive dynamics of an active steering and a hybrid-electric power transmitting unit is presented and analysed to control power distribution between the drive axles of a 4×4 vehicle. A control strategy integrates energy efficiency and lateral dynamics by decoupling dynamics of the two systems thus forming their interactive dynamics.     

Longitudinal wheel slip during ABS braking

Anti-lock braking system (ABS) braking tests with two subcompact passenger cars were performed on dry and wet asphalt, as well as on snow and ice surfaces. The operating conditions of the tyres in terms of wheel slip were evaluated using histograms of the wheel slip data. The results showed different average slip levels for different road surfaces. It was also found that changes in the tyre tread stiffness affected the slip operating range through a modification of the slip value at which the maximum longitudinal force is achieved. Variation of the tyre footprint length through modifications in the inflation pressure affected the slip operating range as well. Differences in the slip distribution between vehicles with different brake controllers were also observed. The changes in slip operating range in turn modified the relative local sliding speeds between the tyre and the road. The results highlight the importance of the ABS controller's ability to adapt to changing slip–force characteristics of tyres and provide estimates of the magnitude of the effects of different tyre and road operating conditions.     

基于ProCAST低压铸造汽车车轮模具型腔有限元分析

通过实例论述了运用ProCAST软件分析低压铸造铝合金车轮模具设计过程中模具的型腔尺寸对铸造件凝固的影响,从而为获得高品质的铸件提供了保证。