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Nowadays, the various virtual tests of a vehicle are increasingly on demand to drastically reduce development cycle time. For the purpose of predicting realistic and accurate vehicle response through the virtual test, a tire model precisely representing real tire property is necessary. This study presents an improved UA tire model as a semi-empirical model. This model provides reasonable data fitting even holding the strength of UA tire model. For that purpose, the main formulations for longitudinal and lateral forces are just re-used. However, cornering stiffness, camber stiffness and driving/braking stiffness are experimentally formulated as functions of load to realistically represent tire characteristics. The formulations of friction coefficients are improved, and also friction characteristic parameters are determined as functions of slip angle, and camber angle and load.

A vehicle pull problem is directly related to safety and comfort. Major parameters causing the pull problem are the PRAT and conicity of tires, the VRAT, cross camber, cross caster and other manufacturing uniformity of a vehicle, and road crown. The effects of these parameters are described in this paper. The significance of VRAT and PRAT is explained as pull matching parameters. Especially, conicity sensitivity and VRAT sensitivity with respect to the changes of cross camber and cross caster are given. To minimize the pull problem, it is shown that a co-work between vehicle and tire companies is necessary from the beginning of a vehicle development to the end

This paper presents the requirements of a tire model used to realistically simulate the cornering maneuvers of passenger cars during driving/braking maneuvers such as J-turn, lane change, slalom, etc In order to overcome the limits of present tire models, new concept is employed. This study examines a force transfer from the contact patch to the wheel as well as a force generation at the contact patch A new definition of slip ratio suitable for vehicle dynamics analysis and closely comparable with are mechanics is introduced A new slip angle is additionally defined in order to conveniently formulate the transient response of a cornering tire Longitudinal force, lateral force and self-aligning moment are semi-analytically formulated as functions of the characteristic parameters of tire compliances, friction and contact pressure

This paper presents an analytical approach for a three dimensional tire model used for the steady-state simulations of vehicles. The functional relationship of slip ratios of the SAE definition and new definition suitable for vehicle dynamics analysis is first studied. New formula for friction is used and a contact pressure change is considered during driving/braking. The compliances of carcass, braker, and tread are employed for longitudinal and lateral elastic deformation. Rolling resistance force, plysteer, and conicity are also included in the explicit formulations of longitudinal force, lateral force, and aligning torque due to comprehensive slips.

This paper presents a comprehensive approach for the mathematical and computer modeling of subsystems required in vehicle dynamic simulations. Three dimensional models for tire-terrain interaction, traction, braking, steering, and suspension systems are presented. The tire-terrain interaction model provides the necessary tire forces and moments which are determined by explicit formulation or experimental data based model. For the suspension subsystem, such elements as bushing, leaf spring, and stabilizer bar are reviewed. For the steering, traction, and braking subsystems, simplified models are discussed. The models developed here can easily be implemented in a three dimensional multibody simulation program.