NUMERICAL ANALYSIS OF NONLINEAR STABILITY FOR RAILWAY PASSENGER CARS

The Newton Raphson iteration and QR algorithm are combined to search the Hpf bifurcation point of the vehicle running on straight track and on large radius curved tracks. Limit cycles that are bifurcated from the equilibrium points and the saddle node bifurcation point are computed through employing a variable step Runge Kutta method and the Poincaré map. Finally, numerical simulations are carried out for the stability of a high speed passenger car operating on straight and large radius curved tracks. The influences of the radius of curvature and the superelevation of the track on the stability of the vehicle system are investigated.

Explicit–Implicit Co-Simulation Techniques for Dynamic Responses of a Passenger Car on Arbitrary Road Surfaces

To study the durability of a passenger car, this work investigates numerical simulation techniques. The investigations are based on an explicit implicit approach in which substructure techniques are used to reduce the simulation time, allowing full vehicle dynamic analyses to be performed on a timescale that is dif cult or impossible with the conventional nite element model (FEM). The model used here includes all necessary nonlinearities in order to maintain accuracy. All key components of the car structure are modeled with deformable materials. Tire road interactions are modeled in the explicit package with contact-impact interfaces with arbitrary frictional and geometric properties. Key parameters of the responses of the car driven on six different kinds of test road surfaces are examined and compared with experimental values. It can be concluded that the explicit implicit co-simulation techniques used here are ef cient and accurate enough for engineering purposes. This paper also discusses the limitations of the proposed method and outlines possible improvements for future work.

FAW Technology Strategies of Low-Carbon Passenger Car

Author analyzed the global background of low-carbon technology around the world,a technology & economy analysis model called TOS was developed in the paper,author analyzed technology paths for low-carbon Car in China based on the current technologies available and technologies to be developed in China,3 possible paths are presented based on the analysis,author also explained the FAW BlueWay technology strategies for low carbon cars both for short mid and long term objectives.Author concludes the paper with illustration of powertrain lineup for FAW BlueWay Technologies.

STUDY ON DYNAMIC CURVING BEHAVIOR OF TILTING PASSENGER CARS

By using tilting carbodies, train can negotiate at a higher speed withoutreducing the passenger's ride quality. This is a good method to allow a significant increase inspeed at existing track to improve the railway transportation capability, and to enhance thecompetition ability of railways with other transportation systems. With the increase of the curvenegotiation speed, the wheel-rail lateral forces and wheel-rail wear of the tilting train willincrease. The self-steering radial bogie is an effective way to solve the problem. The dynamic modelof the tilting passenger car with self-steering bogies is established in detail, and the curvingperformance of the car is investigated.

Performance Development Target Setting of Passenger Car Diesel Engine

Setting engine emission targets to meet diesel car requirements is particularly important in engine performance development phase. Many researches are focused on associating vehicle performance with engine targets, but most work is done by testing, which is time and cost consuming, furthermore, the relationship of vehicle and engine will change when either engine or vehicle changes. A GT-Drive model to simulate New European Driving Cycle (NEDC) for passenger car is developed and calibrated by testing data, model precision is controlled within 5%. Time distribution of engine operating conditions when car running NEDC cycle has been analyzed, 10 critical major engine operating points are summarized according to running time proportion. Emission of NOx and smoke control regions containing these 10 points for target engine are set. Vehicle emissions are simulated and evaluated during engine development after engine performance test data are got, and engine combustion system layout and calibration are adjusted until vehicle targets are met. Vehicle is tested in chassis dynamometer finally, the testing results show a good agreement with the simulated results with an error of less than 5%, which proves that the emission value exchange of vehicle and engine is reliable. Performance target decomposition method for passenger car diesel presented can greatly shorten the development cycle and save costs.

Estimation of Passenger Car Equivalents for Basic Freeway Sections at Different Traffic Conditions

Passenger car equivalent (PCE) is an important factor which is used to convert traffic volumes containing proportions of heavy good vehicles (HGVs) to a unify measure containing only passenger cars units (PCU). This paper uses large data base of real traffic raw data extracted from loop detector before being aggregated to estimate PCEs. These detectors are located on the M25 and the M42 motorway sites in the United Kingdom. The selected sites represent basic freeway segments as they are far away from the influence of entrance (on ramp) and exit (off ramp) sections. The data are filtered properly so as to estimate passenger car equivalents (PCEs) using lagging headway method for close following situations at different speed ranges. The results suggest that for the same location, the equivalency factors are varies significantly based traffic speed. However, it is proved that such variation with traffic speed is influenced by the differences in lengths between HGVs and cars. Regression models have also been developed linking the PCEs with traffic speed.

Kinematic and Kinetic Analysis for the Tilting Mechanism of Railway Passenger Cars

The kinematics and kinetics of the tilting mechanism of railway passenger cars are studied. The parameters of the mechanism are given. The motions of the actuator, the center of gravity of the carbody and the center of coupler are calculated. Finally, the maximum driving force, output power and velocity of the actuator are discussed in detail.

China June Passenger Car Sales Rise 29% on Discounts

China＇s passenger car sales rose 29% in June as automakers cut prices to lure consumers.

Impacts of automated passenger cars on the capacity of a freeway basic section: applicability in the determination of vehicle adjustment factors in mixed traffic

The highway capacity manual(HCM)provides a formula to calculate the heavy vehicle adjustment factor(fHV)as a function of passenger car equivalent factors for the heavy vehicle(ET).However,a significant drawback is that the methodology was established solely based on human-driven passenger cars(HDPC)and human-driven heavy vehicles(HDHV).Due to automated passenger cars(APCs),a new adjustment factor(fAV)might be expected.This study simulated traffic flows at different percentages of HDHVs and APCs to investigate the impacts of HDHVs and APCs on freeway capacity by analyzing their influence on fHV and fAV values.The simulation determined observed adjustment factors at different percentages of HDHVs and APCs(fobserved).The HCM formula was used to calculate(fHCM).Modifications to the HCM formula are proposed,and vehicle adjustment factors due to HDHVs and APCs were calculated(fproposed).Results showed that,in the presence of APCs,while fobserved and fHCM were statistically significantly different,fobserved and fproposed were statistically equal.Hence,this study recommends using the proposed formula when determining vehicle adjustment factors(fproposed)due to HDHVs and APCs in the traffic stream.

Benefits of Reducing Air Emissions: Replacing Conventional with Electric Passenger Vehicles

The study estimated the cost of local and global air emissions, and to compare the differences between electric passenger vehicles (EV) and conventional, internal combustion engine (ICE) vehicles. The air emissions were estimated for the year 2020, for Denmark, France and Israel, because of their significantly different fuel mixes to produce electricity—a high percentage of renewable energy, mainly nuclear energy and high fossil fuels, respectively. Air emissions from electricity production and conventional traffic were calculated for each country and then multiplied by the specific country’s cost of emissions. Subtracting the total cost of electricity production from the total cost of conventional transportation yields the total benefit for each of the economies studied. The environmental benefit, depending on EV penetration rates, was found to be in the range of 7.8 to 133 MEUR/year for Denmark, 94 to1948 MEUR/year for France and only 4 to 82 MEUR/year for Israel, whose energy mix is the most polluting. Our analysis also shows higher potential benefits when replacing passenger car fleets comprising a high percentage of diesel cars with EVs, as well as in highly populated areas. In addition, we quantified the differences between EVs with fixed batteries and the new switch able battery concept (EASYBAT), as part of the EU 7th Framework Program me. The additional electricity demands for the EASYBAT concept are negligible, and therefore, do not change the overall conclusion that the cleaner the electricity energy mix and the higher the penetration of EVs, the higher the environmental benefits achieved.

Virtual Reconstruction of Long Bone Fracture in Car-to-pedestrian Collisions Using Multi-body System and Finite Element Method

Lower limb injures are frequently observed in passenger car traffic accidents.Previous studies of the injuries focus on long bone fractures by using either cadaver component tests or simulations of the long bone kinematics,which lack in-depth study on the fractures in stress analysis.This paper aims to investigate lower limb impact biomechanics in real-world car to pedestrian accidents and to predict fractures of long bones in term of stress parameter for femur,tibia,and fibula.For the above purposes,a 3D finite element(FE) model of human body lower limb(HBM-LL) is developed based on human anatomy.The model consists of the pelvis,femur,tibia,fibula,patella,foot bones,primary tendons,knee joint capsule,meniscus,and ligaments.The FE model is validated by comparing the results from a lateral impact between simulations and tests with cadaver lower limb specimens.Two real-world accidents are selected from an in-depth accident database with detailed information about the accident scene,car impact speed,damage to the car,and pedestrian injuries.Multi-body system(MBS) models are used to reconstruct the kinematics of the pedestrians in the two accidents and the impact conditions are calculated for initial impact velocity and orientations of the car and pedestrian during the collision.The FE model is used to perform injury reconstructions and predict the fractures by using physical parameters,such as von Mises stress of long bones.The calculated failure level of the long bones is correlated with the injury outcomes observed from the two accident cases.The reconstruction result shows that the HBM-LL FE model has acceptable biofidelity and can be applied to predict the risk of long bone fractures.This study provides an efficient methodology to investigate the long bone fracture suffered from vehicle traffic collisions.

A Decision-Support System for the Car Pooling Problem

The continuous increase of human mobility combined with a relevant use of private vehicles contributes to increase the ill effects of vehicle externalities on the environment, e.g. high levels of air pollution, toxic emissions, noise pollution, and on the quality of life, e.g. parking problem, traffic congestion, and increase in the number of crashes and accidents. Transport demand management plays a very critical role in achieving greenhouse gas emission reduction targets. This study demonstrates that car pooling (CP) is an effective strategy to reduce transport volumes, transportation costs and related hill externalities in agreement with EU programs of emissions reduction targets. This paper presents an original approach to solve the CP problem. It is based on hierarchical clustering models, which have been adopted by an original decision support system (DSS). The DSS helps mobility managers to generate the pools and to design feasible paths for shared vehicles. A significant case studies and obtained results by the application of the proposed models are illustrated. They demonstrate the effectiveness of the approach and the supporting decisions tool.

澳大利亚《CAR ADVICE》 大众反对新“咖啡法案”

现在,德国大众公司是为数不多的美国新燃油经济性标准提案的反对者。近日,美国总统奥巴马正式提案,欲提高乘用车燃油经济性标准。目前美国的乘用车燃油经济性标准为每加仑35.5英里(约合每升15.1公里),而新提案中,在2016年到2025年之间,进入美国市场的乘用车必须达到每加仑54.5英里(约合每升23.2公里)。对此。

苯酚-甲醛树脂MK-95在轿车子午线轮胎胎体胶中的应用

研究苯酚-甲醛树脂MK-95(简称MK-95)在轿车子午线轮胎胎体胶中的应用。结果表明:MK-95不含游离间苯二酚和其他添加剂,其软化点和挥发分含量低于间苯二酚-甲醛树脂;在胎体胶中以MK-95等量替代间苯二酚-甲醛树脂,胶料的硫化特性、物理性能、动态力学性能和粘合性能相当,成品轮胎的高速、耐久和路试性能均达到要求。

高速公路同向双向路拱路面小客车换道舒适性和安全性分析

为了分析同向双路拱路面小客车换道行驶舒适性与安全性,使用Carsim仿真软件建立了小客车换道轨迹模型、车辆动力学模型、同向双路拱和单向坡道路模型,以平曲线极限半径值作为换道轨迹半径值,开展多工况跨路拱换道行驶试验,并通过实车驾驶实验对仿真模型进行了准确性验证。结合横向加速度、横摆角速度、峰值附着系数和横向荷载转移率等四项指标变化情况和判断标准对同向双路拱路面小客车换道行驶状态进行了分析。研究结果表明:道路类型对车辆换道行驶稳定性影响较大,综合评价指标与回正增益系数的变化情况,在同向双路拱路面条件下,SUV(suburban utility vehicle)和微型面包车(minivan)换道行驶稳定性均能满足安全行驶要求;换道行驶稳定性由高到低对应的路面类型为:单向坡路面>抛物线型路拱路面>折线型路拱路面;折线型路拱路面条件下,SUV换道行驶稳定性优于Minivan。超速行驶对小客车换道行驶稳定性有显著影响,超速程度越高,稳定越差,即当基础车速为100 km/h和120 km/h时,超速10%和20%时,车辆换道行驶过程中均不存在侧滑风险,但车辆稳定性均处于较差状态。

基于在线评论的乘用车需求趋势分析方法

提出一种基于在线产品评论的竞争情报挖掘方法,将网络评论文本中的关键信息应用于乘用车设计开发中。结合LDA和TF-IDF算法,从主题特征和情感态度特征获取不同车型评论主题情感倾向性估值,并对应2009—2019年的乘用车销量,构建用户偏好分析的面板数据模型。结果显示:该方法能够有效地提取网络评论情报信息;通过与年份的交互作用分析产品需求趋势,过去11年间消费者只对油耗的关注度降低了8.64%,对动力、空间、外观、内饰和舒适性的关注度分别上升了3.16%,6.80%,89.69%,13.38%和18.47%。其中,与生活品质更加密切的外观、内饰和舒适性等指标的增量远高于传统关注的动力和空间指标。这表明燃油经济性越来越不受关注,已不再成为消费者购买乘用车的决定性因素。

铁路客车技术整备所线路配置规模研究

合理确定铁路客车技术整备所的整备线和车底停留线配置规模,对于节约用地和降低工程投资非常重要。TB 10029—2009《铁路客车车辆设备设计规范》第4.3.2条规定,按入所列车数量确定线路数量,并给出相应的计算表。结合规范修订工作,采用线性回归法和概率分析法对线路配置规模进行研究,并对该条规定在当前的适用性进行验证。研究结论如下:(1)按照列车运行图确定客车车底出入客车技术整备所的时间,分析其最大车底停留数量,从而确定整备线和车底停留线数量之和的方法,是确定客车技术整备所线路数量的准确方法。(2)按照入所车底数量和配置系数确定线路数量方法可行,全路客车技术整备所计算平均数量与运行图分析法计算结果的误差为0.3%~7.5%,符合性较好。(3)将3种计算方法应用到具体铁路客车整备所时,全路各所的均方根误差为25%~27%,该误差受运行图编制主客观因素影响,由各客运站列车终到/始发时间分布规律差异造成,可通过运行图调整来适应。

基于事故数据挖掘的乘用车追尾卡车AEB测试规程研究

基于未来出行交通事故场景研究数据库中的乘用车追尾卡车事故,分析并提出了以卡车为目标物的乘用车自动紧急制动系统的典型测试工况。采用K-means聚类算法得出可代表实际卡车的目标物颜色,基于事故数据分析提取卡车目标物尾部特征参数,设计并制作了一种新型的具有与真实车辆反射特性和机器视觉识别特性接近的重型厢式卡车目标物。卡车目标物静止,测试车辆分别以45、50、55、60 km/h的速度进行100%重叠自动紧急制动系统测试,验证了该目标物的可行性和有效性。可为车辆主动安全相关标准法规研究提供数据支撑,推动车辆主动安全测试技术的发展。

某轻型客车钢板弹簧断裂失效原因分析

某轻型客车钢板弹簧在整车耐久试验过程中频繁出现断裂问题。文章通过断口宏观和微观分析、化学成分分析、硬度测试、金相组织检测分析,以及铣削台阶位置和板簧受力特征分析,确定了钢板弹簧断裂的根本原因并制定了改进措施,结合台架试验及整车道路试验进行了验证。结果显示,钢板弹簧卷耳两侧铣削范围过长,导致板簧簧片R角处存铣削台阶,使得此处应力集中进一步提高,导致钢板弹簧在此处断裂。减小钢板弹簧卷耳两侧铣削长度,问题得以解决。