UniTire Tire Model And Application Verification Considering The Influence Of Wear And Temperature

In recent years,with the development of automobile industry,major domestic vehicle companies have fully entered the stage of independent development and basically own the ability to develop chassis by top-down design.However,there are still obvious shortcomings in the high-precision research and application of tire dynamics.The high-precision expression and application of the tire model in all working conditions are one of the key points that restrict the improvement of accuracy of chassis performance simulation and analysis.Establishing high-precision tire models under all working conditions and proposing efficient and reasonable application methods of tire modelshave important research significance for the high-precision simulation,matching and optimization of chassis performanceWith reference to the current research status at home and abroad,there are two core issues in the high-precision vehicle dynamics modeling and tire dynamics model application:(1)The established tire models are generally based on the identification of the indoor six-component force test results,and in the process of testing,tires have a lot of wear and heat generation,but the current tire models do not have the ability to express the mechanical characteristics of tires under different wear conditions and temperatures;(2)Based on the test results of the indoor tire test rig the tire model is directly used for outdoor vehicle dynamics simulation.The inconsistency of the tire’s indoor and outdoor characteristics will inevitably lead to errors in the vehicle simulation,and there is currently no effective solution.This paper focuses on the theoretical problems of tire model and practical engineering application issues,relying on the common technical subject of the Tire Dynamics Collaborative Innovation Alliance "High-precision Application Collaborative Innovation of Tire Models"(Project Number: 20170414045GH)and the National Natural Science Foundation of China funded project " Study of tire high frequency dynamic properties with combined excitations of torque ripple and uneven road in distributed drive electric vehicle"(Approval Number: 51775224),the following research is conducted:(1)UniTire tire model considering wear.Aiming at the problem that the current tire models cannot express the mechanical characteristics of tires under different wear conditions,this paper derives the relationship between the lateral distribution stiffness of the tread model and the height of the tread based on the simplified structural model of the tread.Based on the finite element analysis method,the stiffness characteristics of the tire carcass under different loads and wear conditions are studied.Based on the ground contact pressure distribution test,the change law of tire ground contact characteristics under different wear and different loads is studied,and a ground contact pressure model that can express the ground pressure characteristics of tire with different wear levels is established.Then,according to the laws obtained by the above-mentioned basic theoretical research,a simplified theoretical model considering the elasticity of the carcass is established,and the change law of the key characteristic parameters of the tire with the amount of wear is obtained based on the model.In order to verify the correctness of the laws obtained by the simplified model,a six-component force test of tires under different wear conditions is designed and the results are analyzed.Combining the modeling characteristics of the UniTire model and the relationship between the tire characteristic parameters and the amount of wear,the UniTire tire model is perfected and improved,so that the UniTire tire model own the ability to express the mechanical characteristics of the tire under different wear conditions.Based on the improved UniTire tire model and the six-component force test results of tires with different levels of wear,simulation and test analysis of the multi-condition steady-state characteristics of the tires under different wear are performed to verify the correctness and accuracy of the established UniTire tire model considering wear.(2)UniTire tire model considering temperature.Firstly,modeling of rubber shear stiffness characteristics at different temperatures is performed.With the help of finite element analysis method,a finite element model of the tire at different temperatures is established,and the change law of the rigidity characteristics of the tire carcass at different temperatures is obtained by simulation analysis.Based on the friction test results of rubber samples at different temperatures,the friction characteristics of rubber with temperature are studied and the Savkoor friction model is modified.Based on the rules obtained by the above basic research and the simplified theoretical model of the tire considering the elasticity of the carcass,a simplified theoretical model that can express the mechanical characteristics of the tire at different temperatures is obtained.And then,the law of the tire characteristic parameters changing with temperature is obtained.In order to verify the correctness of the above rulesthe tire cornering stiffness test at different temperatures is designed and the results are analyzed.Combining the modeling characteristics of the UniTire tire model and the change law of tire characteristic parameters with temperature,the UniTire tire model is perfected and improved,so that the UniTire tire model has the ability to express the mechanical characteristics of tires at different temperatures.Based on the improved UniTire tire model and the tire cornering stiffness test results at different temperatures,the tire cornering characteristics simulation and t at different temperatures are carried out to verify the correctness and accuracy of the UniTire tire model that considers the temperature effect.(3)UniTire tire model application method considering the influence of wear and temperature.Firstly,through the simplified tire model,the UniTire cornering model and the direction correction factor model of combined slip are perfected.Based on the above research results and the previous research of the our group,the UniTire own the ability to accurately express the influence of speed,road surface,wear and temperature on the mechanical characteristics of tires.Through the analysis of the environment of indoor and outdoor tires,the factors that have a relatively large impact on tire characteristics are: road condition,tire temperature and tread wear state.Combined with the improved UniTire tire model,the parameters related to the above influencing factors are obtained,and the influence rules of each parameter on the tire mechanical characteristics are studied for the above factors.Then,combined with the characteristics of the model and the statistical rules of a large number of tire data,UniTire tire model application method is proposed to solve the problem of condition inconsistent in tire modeling and application.(4)Validation of UniTire tire model application method considering the influence of wear and temperature.In order to verify the correctness of the UniTire tire model application method proposed in this paper,a verification platform is designed and built: a verification vehicle with no suspension and pure rigidity(hereinafter referred to as " rigid car ").Based on the rigid car’s structure and mass parameters,tire characteristic data,the whole vehicle dynamics model is established.The rigid vehicle dynamics model is equipped with a UniTire tire model that takes into account the influence of wear and temperature.When performing the vehicle stability simulation,one method does not consider the inconsistency of the indoor and outdoor environments,and determines the tire characteristics completely according to the indoor test conditions;the other method considers changes in the outdoor environment,based on the established tire model structure,and reasonably adjusts tire characteristics according to changes in outdoor conditions.The verification rigid car is installed with tires with different wear conditions in different seasons and at different test speeds to verify the handling performace of the vehicle in the proving ground,and the vehicle performance indicators are measured in real time.Finally,the above two simulation results and test results are compared,and the accuracy of the UniTire tire model considering the effects of wear and temperature and the effectiveness of the application method are verifed.