Study On Steady-State Tire Mechanical Properties Considering Camber

The theory boundary conditions considering camber are derived through the establish-ment of steady-state combined camber and cornering brush model and steady-statecombined camber and longitudinal-slip brush model. The generating mechanism oflongitudinal force under combined camber and cornering condition and side force undercombined camber and longitudinal-slip condition is analysed by introducing and promotingthe concept of local carcass camber. Then the corresponding theory boundary conditions canbe derived. UniTire steady-state model considering camber is created and is compared to the‘Magic Formula’ by using the TDFT simulation platform. The significance of this study is toestablish the steady-state UniTire model considering camber which meets the theoryboundary conditions and to correctly describe longitudinal force under combined camber andcornering condition and side force under combined camber and longitudinal-slip condition.Besides, the extensionality and forecasting capabilities of UniTire model dealing withcamber are improved.Firstly, the steady-state combined camber and cornering brush model is established andthe related theory boundary conditions are derived. Then, the lateral force curvature of theUniTire model is corrected. In addition, the study shows that the camber has a directionalimpact on the cornering properties and affects the change rate of the transition phase of thealignment torque arm so that the pneumatic drag peak factor and curvature factor are revised.Secondly, the steady-state combined camber and longitudinal-side brush model isestablished. According to the model, the impact of the camber to longitudinal mechanicalproperties is mainly decided by the changes of the half contact length and the longitudinalslip along the direction of the tire width. The concept of local carcass camber is introducedand promoted to study the interaction mechanism between camber, effective camber, halfcontact length and load radius. The local carcass camber is mainly decided by camber,effective camber and lateral force. The change of the half contact length along the directionof tire width is mainly determined by effective camber and the change of the longitudinalslip. The effective camber is determined by all factors affecting the local carcass camber. Based on these results, the mechanism that the lateral force changes the longitudinal force byaffecting the effective camber is revealed and the mechanism that the longitudinal slipvelocity possesses the lateral component is clarified. The longitudinal slip and lateral slip ofthe UniTire model are revised.Thirdly, the impact of the camber to the lateral friction coefficient and corneringstiffness is researched by using the method of combining the theory analysis and experiment.Then, the related semi-empirical model is established. The generation mechanism of theresidual aligning torque is analysised and then the related semi-empirical model isestablished. The UniTire steady-state model considering camber is validated by test.Finally, the ‘Magic Formula’ is compared with the UniTire model considering camberby using the TDFT simulation platform. They have similar accuracy to deal with typicaloperations. The UniTire model considering camber has better accuracy to deal with the largecamber operation than the ‘Magic Formula’. The ‘Magic Formula’ dealing with thelongitudinal force under combined camber and cornering condition is defective. The UniTiremodel considering camber can correctly deal with the the longitudinal force under combinedcamber and cornering condition and the lateral force under combined camber andlongitudinal-slip condition.