Modeling Of Unitire Transient Model Under Full Conditions And Application In Vehicle Simulation

Tire dynamics is an important branch of vehicle dynamics. After long-term research anddevelopment, a series of achievements have been achieved in tire steady state dynamics, suchas theoretical model, empirical model, semi-empirical model, physical model and so on. Withthe development of finite element technology, tire finite element model has been widely used.Tire finite element model can not only save time-cost, but also can simulate under conditionthat tire test bench is not easy to achieve. In most cases, vehicle is in unstable state, thereforetire transient mechanical characteristics has important effect on vehicle performance. In termsof tire unsteady mechanical characteristics, the researchers mainly focused on lateral andlongitudinal non-steady research and relatively pay little attention to camber non-steadycondition. Cambered tire has an important influence on vehicle and rationally selecting theparameters of wheel alignment. In order to meet the requirements of tire model for allconditions and high precision, it’s necessary to broaden the research of non-steady state.Based on the above reasons and take previous tire non-steady model into account, this papercarried out the following research work:1. Analysis and modeling Non-Lagging Part. Firstly, using tire finite element model tosimulate three different loading conditions. Analysis the reason that the force caused by threedifferent loading ways, through compares simulations with or without road friction coefficient.Finally, analyze reasons that different forces caused by three loading ways under thehypothesis of tread brush without stiffness and road without friction, and then modeling.2. Establish UniTire transient model under full conditions. First of all, using tire finiteelement model to simulate non-steady state of three different loading ways to verify ifuniformity. Based on the uniformity, use tire finite element model to simulate lateralnon-steady, longitudinal non-steady, lateral steady and static lateral stiffness condition. Lateralnon-steady includes lateral sliding non-steady condition, camber non-steady condition,camber and lateral sliding combined condition. And longitudinal non-steady includes longitudinal sliding non-steady, longitudinal sliding and camber combined condition.Analyzing the influence caused by camber, and put lateral sliding speed into lateralnon-steady model. Due to the introduction of camber, relaxation length will change and thenintroduce equivalent dynamic lateral stiffness to revise relaxation length. Through modelingof initial lateral force, lateral sliding speed, relaxation length to modify non-steady model.3. Verify UniTire transient model under full condition. Tire static condition, Lateralsteady condition, Lateral non-steady condition are tested on low speed tire test bench. Tirestatic experiments include Non-Lagging Part and static lateral stiffness testing. The result iscompared between tire test and finite element model simulation to prove the validity ofmodeling approach. Finally, compare UniTire transient model under full condition simulationdata with test data to verify the accuracy of the model.4. Model application. UniTire are embedded into Carsim. And compare simulationresults between UniTire and internal model under straight line test, understeer test on circle toprove the correctness of model connection. Through vehicle typical conditions simulate toanalyze response of transient model.