液罐汽车横向稳定性的研究

对液罐车非满载工况下在水平道路上转弯行驶以及在侧坡道路上直线行驶和转弯行驶时的液体质心坐标和横向稳定性进行了分析研究。在水平道路上转弯行驶时，质心的转移及侧倾程度主要与转弯半径，车速等有关；在侧坡道路上直线行驶时，质心的转移及侧倾程度主要与坡道的角度有关，在侧坡上转弯行驶时，质心的转移及侧倾程度除与侧坡角度有关外，还与转弯半径和车速等有关。为了减少液体质心的转移对汽车横向稳定性的影响，可在罐内增加纵向隔板，来抑制液体质心的转移。     

油罐车转弯横向稳定性的计算分析

油罐车平地急转弯和坡上转弯是容易引起横向翻倾的危险工况。由于油罐留有扩大容量和油液的流动性，转弯时油液质心偏移，导致横向稳定性减弱，本文分析并推导了具有椭圆截面罐体的油罐车转弯时的横向翻倾临界坡度角和转向加速度的计算公式，介绍了横向稳定特性曲线的绘制方法，并给出了计算实例。     

Estimation of the Non-Linear Suspension Tyre Cornering Forces from Experimental Road Test Data

The paper discusses the application to real data of an identification procedure based on an Extended Kalman Filter, for estimating the equivalent non-linear suspension tyre cornering forces of a road vehicle from a single standard manoeuvre. In particular, both the steady-state and the dynamic handling characteristics can be evaluated.     

低地板城市客车车身结构有限元分析

利用标准的CAE软件平台，对低地板城市客车车射结构进行数值建模和静动态特性分析，计算时考虑客车实际运行中出现的多种典型工况，如直线匀速行驶，路面高低不平出现单轮瞬间悬空、紧急制动及急转弯等工况，并详细讨论了相应载荷及边界条件的施加方法。     

Estimation of the tyre–road maximum friction coefficient and slip slope based on a novel tyre model

In this article, a new approach to estimate the vehicle tyre forces, tyre–road maximum friction coefficient, and slip slope is presented. Contrary to the majority of the previous work on this subject, a new tyre model for the estimation of the tyre–road interface characterisation is proposed. First, the tyre model is built and compared with those of Pacejka, Dugoff, and one other tyre model. Then, based on a vehicle model that uses four degrees of freedom, an extended Kalman filter (EKF) method is designed to estimate the vehicle motion and tyre forces. The shortcomings of force estimation are discussed in this article. Based on the proposed tyre model and the improved force measurements, another EKF is implemented to estimate the tyre model parameters, including the maximum friction coefficient, slip slope, etc. The tyre forces are accurately obtained simultaneously. Finally, very promising results have been achieved for pure acceleration/braking for varying road conditions, both in pure steering and combined manoeuvre simulations.     

集装箱运输车在不同坡道条件下燃油经济性的试验

通过理论分析、实车道路试验、加载或减载的模拟试验方法,研究了集装箱运输车在不同坡道上行驶时的燃油经济性,以作为客观评价在集装箱堆场最大允许纵坡道路条件下集装箱运输车经济性的指标。结果表明道路纵坡度的增加对汽车上坡时的油耗量影响很大,且载荷越大,影响越大。     

客车侧倾与横摆动力学稳定集成控制系统（续1）

客车在急转弯时,侧倾运动对其横向载荷转移率和轮胎垂向受力的改变,不仅会引起侧翻事故,还会对横摆运动产生重要影响。文章综合分析客车侧倾、横摆动力学及其耦合关系,建立耦合动力学模型。采用差动制动和主动式防倾杆等主动控制方法,并基于滑模控制理论设计集成控制系统。仿真结果表明,该系统可提高客车侧倾与横摆动力学稳定性,实现客车防侧翻和防侧滑的综合功能。     

Static Turning Analysis of Vehicles Subject to Externally Applied Forces - A Moment Arm Ratio Formulation

A formulation for representing the static turning response of a two-axle vehicle due to applied external or control forces is expressed in terms of a simple ratio of two distances along the vehicle longitudinal axis. The two distancescoincide with points on the vehicle at which externally applied/ control forces and their reactive inertial forces act with respect to the vehicle neutral steer point. The resulting formulation is equivalent to the rotational equilibrium equation written with respect to the neutral steer point. The method allows a simple “visual analysis” of the steady turning process by showing how key forces and associated moment arms can change with respect to one another due to vehicle modifications or different operatingconditions, thereby affecting the static turning response of the vehicle.     

自锚式悬索桥恒载吊索力的设计方法研究

基于内力平衡法,对自锚式悬索桥的成桥吊索力进行研究。首先用弯矩能量最小原理求出初步索力,然后利用索力得到恒载弯矩,利用挠度理论求出活载作用下结构的最不利弯矩,将恒载与活载弯矩叠加,获得结构的初步控制弯矩后,采用内力平衡法对弯矩和索力进行调整以得到合理的索力。     

Static Turning Analysis of Vehicles Subject to Externally Applied Forces - A Moment Arm Ratio Formulation

SUMMARY

A formulation for representing the static turning response of a two-axle vehicle due to applied external or control forces is expressed in terms of a simple ratio of two distances along the vehicle longitudinal axis. The two distancescoincide with points on the vehicle at which externally applied/ control forces and their reactive inertial forces act with respect to the vehicle neutral steer point. The resulting formulation is equivalent to the rotational equilibrium equation written with respect to the neutral steer point. The method allows a simple “visual analysis” of the steady turning process by showing how key forces and associated moment arms can change with respect to one another due to vehicle modifications or different operatingconditions, thereby affecting the static turning response of the vehicle.     

Overturning Stability of Three Wheeled Motorized Vehicles

Three wheeled motorized vehicles are a major mode of public transport in many countries. These vehicles are prone to overturning even during normal turning and obstacle avoidance maneuvers. This paper presents a parametric analysis of a mathematical model of the vehicle and evolves guidelines for improving the overturning stability in terms of vehicle geometry and suspension properties.

Differential equations governing the dynamic behavior of the vehicle are derived on the basis of a six degree of freedom model. The vehicle response to variations in steering, engine power and braking inputs is then numerically simulated. The effects of vehicle geometry and elasto-damping suspension coefficients on the vehicle stability are presented. The results indicate an optimum position of the center of gravity where the vehicle is most stable. While stiffer suspensions favour stability, there exists an optimum value of suspension damping for which the minimum wheel load is a maximum.     

基于弯道影响的交通流特性研究

针对弯道是交通事故多发路段,基于元胞自动机Nagel-Schreckenberg交通流模型(简称NaSch模型),建立包含弯道路段在内的元胞自动机模型.采用数值仿真研究,在开放边界条件下研究了不同弯道曲率半径、弧长、摩擦系数等因素对交通流的影响.数值模拟结果表明,弯道曲率半径、弧长和摩擦系数对交通流的影响都很大,通过增大弯道半径和摩擦系数,减少弯道弧长都可以提高交通流量、平均速度,从而减少交通拥堵、交通事故的发生,提高弯道路段的通行能力.     

关于公路路基设计规范中挡土墙倾覆稳定方程表达式的商榷

《公路路基设计规范》 (JTG D30—2004)对挡土墙的设计首次提出了以荷载分项系数法为主的设计方法，即滑移和倾覆稳定采用分项系数法设计、地基承载力采用容许应力法设计。根据荷载分项系数法，相同的分项系数因荷载对挡土墙结构的不同作用效果必须取用不同的数值。但是，规范对倾覆稳定方程表达式表述含混，容易出错。根据分项系数的不同取值，对挡土墙倾覆稳定进行了大量计算，并与总安全系数法的计算结果进行比较，提出了倾覆稳定方程的修正表达式，供大家商榷。     

Vehicle Dynamic Control for In-Wheel Electric Vehicles Via Temperature Consideration of Braking Systems

?Vehicle dynamic control (VDC) systems play an important role with regard to vehicle stability and safety when turning. VDC systems prevent vehicles from spinning or slipping when cornering sharply by controlling vehicle yaw moment, which is generated by braking forces. Thus, it is important to control braking forces depending on the driving conditions of the vehicle. The required yaw moment to stabilize a vehicle is calculated through optimal control and a combination of braking forces used to generate the calculated yaw moment. However, braking forces can change due to frictional coefficients being affected by variations in temperature. This can cause vehicles to experience stability problems due an improper yaw moment being applied to the vehicle. In this paper, a brake temperature estimator based on the finite different method (FDM) was proposed with a friction coefficient estimator in order to solve this problem. The developed braking characteristic estimation model was used to develop a VDC cooperative control algorithm using hydraulic braking and the regenerative braking of an in-wheel motor. Performance simulations of the developed cooperative control algorithm were performed through cosimulation with MATLAB/Simulink and CarSim. From the simulation results, it was verified that vehicle stability was ensured despite any changes in the braking characteristics due to brake temperatures.     

Handling stability improvement through robust active front steering and active differential control

The design of the integrated active front steering and active differential control for handling improvement of road vehicles is undertaken. The controller design algorithm is based on the solution of a set of linear matrix inequalities that guarantee robustness against a number of vehicle parameters such as speed, cornering and braking stiffnesses. Vehicle plane dynamics are first expressed in the generic linear parameter-varying form, where the above-stated parameters are treated as interval uncertainties. Then, static-state feedback controllers ensuring robust performance against changing road conditions are designed. In a first series of simulations, the performance of the integrated controller is evaluated for a fishhook manoeuvre for different values of road adhesion coefficient. Then, the controller is tested for an emergency braking manoeuvre executed on a split-μ road. In all cases, it is shown that static-state feedback controllers designed by the proposed method can achieve remarkable road handling performance compared with uncontrolled vehicles.     

车辆动力转向系统非线性仿真研究

车辆液压动力转向系统通过伺服阀控制压力油的方向和流量,把转向盘输入的转角信号转变为车轮的偏转角度输出。在车轮偏转过程中,影响车轮偏转的力主要是地面摩擦力和轮胎的弹性变形力,因而动力转向系统所受干扰力的基本特性是非线性的,文中结合液压系统理论和Simulink控制系统仿真软件,计算并仿真了在非线性干扰力作用下的液压式动力转向系统的动态特性。     

铁路集装箱运输动态服务网络设计及Benders分解算法

充分考虑箱流的中转方案，研究铁路集装箱运输动态服务网络的设计方法。以总成本最小为优化目标，构建了铁路集装箱运输动态服务网络设计的线性规划模型。根据模型特点，采用Benders算法进行求解，将问题分解为服务网络设计的主问题及箱流分配的子问题，通过计算子问题的对偶模型不断产生主问题的割平面，由此进行迭代求解。为克服算法收敛速度慢的缺点，在主问题模型中添加有效不等式，使主问题更加紧致。以北京、郑州等集装箱办理站构建的运输网络为例，验证了模型和算法的有效性。算例结果表明，对于求解大规模的集装箱运输动态服务网络设计问题，改进后的算法运行46 s得到优化解，GAP为1.56%，未改进的Benders算法运行相同时间后，GAP为45.17%，改进策略的运用有效提高了计算效率; 所得服务网络的总成本比所有箱流均采用直达运输模式服务网络的总成本减少了20%;与现有集装箱班列开行方案相比，优化后的班列发车时段、开行频率在满足运输需求的同时，保证了各组箱流能在规定运到期限内送至目的站。      

Dynamics of Pneumatic Tire Vehicles with Connected Suspension Systems

A vehicle model, with 10 degrees of freedom is used to investigate the skidding conditions of any wheel of the vehicle in motion. Equations for the load transfer and equations for the pneumatic tire spring and shock absorber are derived. Parameters such as gradual cornering, U-curve cornering, the wavy road surface of different wave lengths and cases of independent and connected suspension systems are inputs to the system. The tire calculated forces and their corresponding maximum resistance forces are the outputs of the systems. A connected suspension system is found to resist skidding better than the independent suspension system. The system is non-linear, and numerical solutions are obtained.     

On the Destabilizing Effect of Liquids in Various Vehicles* (part 1)

The unrestrained free surface of a liquid has an alarming propensity to undergo large excursions for even very small motions of the container. This fact may endanger the stability, as well as the riding and maneuvering quality of the vehicle considerably. It is particularly true for fuel- or cargo tanks of automotive vehicles, railroad tank cars, for fuel tanks of large ships and tankers, for which violent sea conditions at times result in fairly large amplitudes of pitching, heaving and rolling, as well as for airplanes and spacevehicles flying through atmospheric disturbances. The response of liquids contained in cargo- or fuel tanks is therefore of quite some concern, especially in those cases where the sloshing liquid masses occupy a large amount of the total mass of the vehicle.

For this reason the theory of liquid motion with a free surface is presented for containers of various geometries. Forces and moments of the liquid exerted upon the vehicle are presented and a simple mechanical model for the representation of the liquid motion is derived. Methods for the reduction of the destabilizing effect of the liquid motion, such as baffles, cross walls and surface coverings are presented and shall exhibit their effectiveness. In addition the interaction of the liquid motion with the elastic structure of the container, as well as the interaction with a controlling system of the vehicle shall be demonstrated. Stability boundaries, design criteria and dynamic responses to disturbances shall be presented for a particular case.     

Development of crosswind spoiler

Aerodynamic steady flow simulations for One-Box type automobiles in crosswind conditions are carried out using the k—ε turbulence model and a third-order upwind scheme with modified production method. The factor of yawing moment is observed and an effective device (Crosswind Spoiler) for reducing yawing moment is found by these numerical results. Experimental verifications in wind tunnel and on road tests are also presented.