The Study Of Tire Hydroplaning Mechanism On Wet Road

As the only contact part between vehicle and road surface,the adhesion performance of tire has a very important impact on the safety of vehicle driving and personal safety.Especially on wet and slippery roads or in rainy weather,the occurrence of accidents is greatly increased because of the sharp decrease of tire adhesion coefficient and the hydroplaning phenomenon of vehicles.Therefore,the hydroplaning performance of tires on wet and slippery roads has become the research focus of scholars at home and abroad.At present,the domestic research on tire hydroplaning performance mainly focuses on Simulation test and the theoretical research is still in its infancy.In this paper,the mathematical model of tire hydroplaning is established from the theoretical analysis,and the effects of speed and load on tire hydroplaning are studied respectively to improve the theoretical model of tire hydroplaning,which provides reference value for tire research and design.(1)Through the analysis of domestic and foreign research on tire hydroplaning,this paper obtains the reasons and influencing factors of tire hydroplaning.Based on the theory of elastohydrodynamic lubrication,the lubrication system between tire,water and road three is established.The Reynolds equation is established by the force analysis of fluid element,and the integral equation of water film thickness is obtained by using the first-order Lagrange function as the deformation function and the compliance matrix.(2)Multigrid technique is used to solve the mathematical model.The mathematical model is dimensionless and meshed in the tire contact area.The equations are discretized on each grid.Multigrid method is used to solve Reynolds equation and multigrid integration method is used to solve water film thickness equation.The convergence of the model is obtained repeatedly on the mesh.(3)The solution of the tire hydroplaning equation on the grid is programmed by FORTRAN software.And the results of water film thickness and fluid pressure are obtained by running the program.The water film thickness distribution and fluid pressure distribution at different vehicle speeds were obtained by changing the velocity parameters,and the center water film thickness and the minimum water film thickness at corresponding velocity were obtained.By changing the external load parameters,the data of water film thickness distribution and fluid pressure distribution under different loads are obtained.Using MATLAB software to process the data,water film thickness distribution and fluid pressure distribution graphs under different vehicle speeds and different loads are obtained,as well as the graphs corresponding to the center film thickness and the minimum film thickness at different velocities.As can be seen from the figure,with the increase of the speed,the pressure difference between the two ends of the tire decreases,the drainage performance of the tire decreases,the thickness of the water film increases,and the probability of water skiing increases greatly;According to the distribution of the central water film thickness,the equation of water film thickness and velocity is regressed.With the increase of load,the pressure of tire water supply increases,and the drainage rate of tire increases,which improves the anti-sliding performance.Therefore,the results obtained in this paper accord with the characteristics of elastohydrodynamic lubrication.(4)The simulation results are compared with the results obtained by finite element software from the two factors of vehicle speed and load.Theoretical results and simulation results show that the anti-water-sliding performance of tire decreases with the increase of vehicle speed.With the increase of load,the drainage performance of tire is improved,which verifies the validity of the research results in this paper.