Shear Force Development by Pneumatic Tyres in Steady State Conditions: A Review of Modelling Aspects

SUMMARY

Modelling of the generation of shear forces by pneumatic tyres under steady state conditions is reviewed. The review is placed in a practical context, through reference to the uses to which models may be put by the vehicle dynamicist and the tyre designer. It will be of interest also to the student of rolling contact problems.

The subject is divided into sections, covering physically founded models which require computation for their solution, physically based models which are sufficiently simplified to allow analytical solutions and formula based, empirical models. The classes are more nearly continuous than this strict division would imply, since approximations in obtaining analytical solutions may be made, empirical correction factors may be applied to analytical results and formula based methods may take into account tyre mechanical principles. Such matters are discussed in the relevant sections. Attention is given to the important matter of choosing model parameters to best represent the behaviour of a particular tyre.

Conclusions relate to the structural and frictional mechanisms present in the shear force generation process, the contributions of carcass and tread elastic properties and of geometrical and frictional factors to the determination of the distributions of force through the contact region, the relationship between accuracy and computational load and the selection of methods for modelling tyre forces in a road vehicle dynamics context. Reference to the most pertinent literature in the field is made and possibilities for the further development of the state of the art are mentioned.     

轮胎制动与驱动特性的理论模型

轮胎印迹内垂直载荷的分布与形式的选择，对建立轮胎制动与驱动特性的理论模型有很大影响。根据轮胎制动和驱动时印迹内垂直载荷分布特性，以及轮胎的前后变形特性，建立了轮胎制动、驱动特性的理论模型。应用该理论模型的计算结果，与试验结果具有很好的一致性。     

基于数据库的数模在公路CAD中的应用

着重于数字地面模型（ＤＴＭ）在公路路线ＣＡＤ的实用技术,介绍在ＡｕｔｏＣＡＤ图形环境下,基于ＡＣＣＥＳＳ数据库的数字地面模型的排序分格、构网、优化、交互编辑及生成纵、横地面线和三维地面模型,有较好的理论与实用价值。     

发动机万有特性的数学模型

本文提出了一种发动机万有特性的数学模型,为汽车燃料经济性计算和汽车动力传动系匹配提供了依据。     

基于MATLAB的气动凿岩设备气室压力信号的计算机仿真

对风镐气室压力信号进行了计算机仿真，并对活塞的运动规律进行了仿真分析，仿真结果与风镐正常工作的各项性能要求一致，说明运用仿真的方法研究气室的压力信号变化规律是一种可行的方法。     

Vibrations Generated by Rail Vehicles: A Mathematical Model in the Frequency Domain

Movement of railway vehicles generates mechanical vibrations of a wide range of frequency. Depending on track materials, dissipation in form of viscous and hysteretic damping is present, and stiffness depends on strain-rate. In a previous paper (Castellani et al., 1998), a mathematical model to describe track materials has been developed in the frequency domain. The present paper applies this model, and attempts an analytical formulation of vehicle-track and soil interaction in the frequency domain. Rail vibrations during the passage of a vehicle are generated by three families of forces: a) the weight of the moving vehicle, b) the inertial reaction of the vehicle under the effect of corrugations over an undeformable rail, and, c) the vehicle inertial forces due to displacements of the rail. The first two groups of forces do not depend on the rail displacement, and the related mathematical formulation is a simple problem of forces at a mobile point of application. Formulation of the vehicle inertial forces, related to the rail vibration, requires reference to the acceleration of the rail, as seen by an observer in motion with the vehicle itself. Moreover, it is necessary to express the equilibrium equation of two dynamic systems, the vehicle and the track, at a the movable point of contact. There is no straight numerical procedure to solve this equation in the frequency domain. In the paper two theoretical propositions (Fryba, 1988; Grassie et al., 1982) are revisited with reference to the effect of the transit of a single wheel. Fryba infers that, in the absence of corrugations, the forces c) are null. Grassie et al. (1982) present a mathematical formulation of the interaction between wheel and rail, at mobile point of contact. At each position, the interaction force is of impulsive type. They presume that for a corrugation of harmonic type, of wavelength ?, the wheel is subject to a harmonic motion, of the frequency f = V/?, where V is the wheel velocity. All other frequency components, due to the impulse, are disregarded. Both these assumptions are shown to be inconsistent from a theoretical point of view, however they suggest suitable approaches to the solution.     

汽车空调管带式冷凝器数学模型研究

通过引入当地局部参数概念和两相流理论，对汽车空调用管带式冷凝器提出一个新的稳态分布参数数学模型和计算方法。在换热量为6～8kW的范围内，通过模型仿真计算与试验结果的对比，验证了模型的准确性，并分析了弯头对模型仿真计算的影响。     

基于计算机视觉的汽车四轮定位参数检测数学模型及方法研究

鉴于传统的四轮定位技术存在需要的传感器众多、标定复杂、操作繁琐以及检测速度慢、精度不高等问题,应用计算机视觉理论建立了一种四轮定位参数检测数学模型,重点阐述了对该模型进行求解的过程,并根据所建数学模型及实车检测实验给出了测量方法和步骤.实验结果表明,所提出的模型及方法是正确和有效的.     

A Model Reduction Procedure for the Dynamic Analysis of Rail Vehicles Subjected to Linear Creep Forces

The set of differential equations governing the motion of an unrestrained coned wheelset travelling on a tangent section of track and acted upon by creep forces arising from the contact between wheel and rail are, in the terminology of numerical analysis, extremely "stiff". This stiffness can be attributed to the existence of two negative real eigenvalues in the solution of the eigenproblem associated with the linearized equations of motion. Compared with the two complex conjugate eigenvalues that complete this solution, the real eigenvalues have large magnitudes and necessitate that relatively. small timesteps be used in order to obtain an accurate numerical integration of the full set of equations of motion. However, by truncating the set of left and right eigenvectors to eliminate these real eigenvalues in a modal analysis of the wheelset, it was found that their contribution to the overall dynamic response is negligible. This same modal truncation approach was then applied to the sub-structured equations of motion for a simple rail vehicle system consisting of two wheelsets connected to a main body by linear springs and dampers. Essentially, the physical degrees of freedom for each wheelset substructure were replaced by a single complex coordinate obtained from the previous normal modes analysis. Using this model reduction procedure, accurate numerical results for the motion of the rail vehicle were generated several times faster than the results obtained by numerically integrating the full set of differential equations directly.     

基于耦合电感理论的同步电机数学模型分析

从耦合电感理论的角度出发，以动生电动势和感生电动势等效分析为依据，运用基本的电磁理论从不同的方向对同步电机的模型进行讨论，推导出一种同步电机的“新”数学模型，并在“新模型”的支持下讨论了与同步电机相关的几个具体问题。     

基于多维模型的电喷汽油机MAP图的数值生成

将DPIK点火模型和单步燃烧模型集成在K IVA-3V中,构建汽油机MAP研究的多维模型。对汽油机工作过程进行数值模拟,并以动力性、经济性和指示功为控制条件,结合试验数据对点火提前角和喷油脉宽进行优化。研究表明:用多维模型模拟的方法生成的MAP可以作为电喷汽油机的初始MAP。     

A Modular Computer Model for the Design of Vehicle Dynamics Control Systems1

This paper describes a multiport approach to computer-aided modeling of vehicle dynamics. The modeling approach produces models that are suitable for the interactive design and evaluation of complex control strategies. The vehicle model which can be used for ride and handling analysis, is built from modular components. The components are programmed using the syntax of the computer aided control system design (CACSD) program EASYS. Seven modeling components are used to create a three-dimensional vehicle dvnamics model. The model is flexible enoug-h to simulate any suspension design with revolute joints.

Each component of the model consists of a FORTRAN subroutine and a main calling module called a macro. To simplify the process of model building, the modeling components in the car model are designed to represent physical elements, such as the spring, damper, link or tire. To create a model, the components, which are represented by blocks, are interconnected through points, located on the blocks, called pons. These ports have been designed to simulate the location of the connection points between the physical elements, as observed in real systems. The construction of multibody models within a CACSD program offers the flexibility of simultaneous interactive simulation of the three-dimensional dvnamics and evaluation of the desien of the controls.

Although modeling of multibody systems using FORTRAN components has been pioneered by Chace, Haug and Orlandea; and bond graph modeling of multibody systems has been investigated by Bos, this approach is novel because:-

The model is included in the control system design program (EASYS). This arrangement allows the designer to exploit the advanced control design tools available in the program. Furthermore, this approach significantly reduces the computation time required for running the model after parameters modification.

The model is built from components that are interconnected by ports which represent the actual physical location of the connection points between the elements. The multiport approach simplifies the model building process for multibody systems. This simplification is achieved by reducing the model of a multibody system to a block diagram form.     

A Modular Computer Model for the Design of Vehicle Dynamics Control Systems1

SUMMARY

This paper describes a multiport approach to computer-aided modeling of vehicle dynamics. The modeling approach produces models that are suitable for the interactive design and evaluation of complex control strategies. The vehicle model which can be used for ride and handling analysis, is built from modular components. The components are programmed using the syntax of the computer aided control system design (CACSD) program EASYS. Seven modeling components are used to create a three-dimensional vehicle dvnamics model. The model is flexible enoug-h to simulate any suspension design with revolute joints.

Each component of the model consists of a FORTRAN subroutine and a main calling module called a macro. To simplify the process of model building, the modeling components in the car model are designed to represent physical elements, such as the spring, damper, link or tire. To create a model, the components, which are represented by blocks, are interconnected through points, located on the blocks, called pons. These ports have been designed to simulate the location of the connection points between the physical elements, as observed in real systems. The construction of multibody models within a CACSD program offers the flexibility of simultaneous interactive simulation of the three-dimensional dvnamics and evaluation of the desien of the controls.

Although modeling of multibody systems using FORTRAN components has been pioneered by Chace, Haug and Orlandea; and bond graph modeling of multibody systems has been investigated by Bos, this approach is novel because:-

The model is included in the control system design program (EASYS). This arrangement allows the designer to exploit the advanced control design tools available in the program. Furthermore, this approach significantly reduces the computation time required for running the model after parameters modification.

The model is built from components that are interconnected by ports which represent the actual physical location of the connection points between the elements. The multiport approach simplifies the model building process for multibody systems. This simplification is achieved by reducing the model of a multibody system to a block diagram form.     

基于接合指标逻辑切换的气动离合器控制算法研究

针对AMT气动离合器自动控制系统,采取了基于离合器接合指标逻辑切换的PID控制算法,其中电磁阀的控制采用PWM开关阀的比例控制,并基于该控制算法搭建了该系统的控制器。在AMESim中对AMT气动离合器自动操纵系统建模,并进行相关的仿真。离合器自动操纵系统的台架试验,验证了所制定的控制算法的有效性,大大提高了离合器的接合品质。     

多因素分析薄壁曲线箱梁剪滞效应的力学模型

利用最小势能原理建立了考虑多因素的分析薄壁曲线箱梁剪滞效应的控制微分方程及其边界条件,为考虑多因素薄壁箱梁剪滞效应建立了理论分析基础。     

基于影响矩阵法的斜拉桥成桥索力优化

介绍了斜拉桥成桥索力优化的影响矩阵法,运用大型有限元程序ANSYS中的优化模块,结合某独塔斜拉桥验证了这种方法计算合理成桥索力的可行性和有效性。计算结果表明,将影响矩阵法引入斜拉桥成桥索力的有限元分析中是可行的,可为类似桥梁的设计提供参考和验证。     

基于MapGIS的数模建立方法及其在路线CAD中的应用

针对公路勘测设计一体化的特点与要求,论述应用GIS技术采集公路地面数据和建立数字地面模型的方法;研究MapGIS系统在公路选线和CAD中的应用。在分析地理信息系统与公路勘测设计关系的基础上,根据我国公路路线设计CAD发展的实际情况,提出基于MapGIS平台进行公路路线设计应用软件开发的建议。     

采用数字图像处理技术和内聚力模型模拟沥青混合料裂缝扩展

裂缝是沥青混凝土路面的主要病害之一。通常,对沥青混合料的裂缝研究没有考虑沥青混合料细观结构的各向异性,对于裂缝尖端的塑性特征也研究不足。采用数字图像处理技术,实现沥青混合料细观结构的有限元二维建模,采用内聚力模型对单调加载情况下半圆弯拉试验裂缝的动态扩展进行数值模拟,此研究可以进一步发展到疲劳特性研究。