Study On The Friction And Wear Mechanism Of Wheel-brake Pad Interface During Train Tread Braking Process

In recent years,China’s railway industry has developed rapidly.High-speed and heavy-load are the inevitable trend of railway development.The friction and wear problems of the wheels also follow.The polygonal wear of the wheel tread is a typical friction damage,and because the friction of the brake shoe generates a lot of heat during the braking process of the train,the wheel material will be affected with the increase of temperature.In addition,the polygonal characteristics of the wheel tread will affect the distribution of temperature and stress,resulting in new friction damage and fatigue damage of the wheel,rail and brake shoe under the combined action of thermal stress and uneven load,The reduction of wheel service life is aggravated.In addition,the rail creep and the pure sliding of the brake shoe wear the wheel tread at the same time.In addition,the polygonal characteristics of the wheel tread lead to the friction and wear competition among the rail,wheel and brake shoe.In order to study the friction and wear mechanism of the wheel-brake shoe contact interface and consider the polygonal wear characteristics of the wheel tread,the three-dimensional finite element model of the rail-wheel-brake shoe is established in Abaqus and the material properties are set.Considering the heat transfer properties such as convective heat transfer,wheel-rail contact heat transfer and thermal radiation,the braking process of the train tread is simulated according to the actual braking conditions of the train Distribution of temperature field and stress field on the contact surface of brake shoe.On the basis of obtaining the temperature field and stress field of the tread,based on the Archard wear model,and taking into account the creep of the rail,the tread wear area is divided.Based on this model,the wear depth of the tread is calculated by secondary development of the Umeshmotion subroutine with Fortran language,and the wear node is offset with ALE grid technology.The rail,wheel The competitive relationship among the three brake shoes and the influence of polygon characteristics on the wear depth.Considering that the contact surface of wheel brake shoe has certain roughness,the sliding contact model of double rough surface is established based on W-M fractal function from the mesoscopic scale.The distribution of contact stress and real contact area of rough surface is obtained through simulation analysis.On this basis,the influence of temperature on the material is considered,the friction coefficient of rough surface is extracted for nonlinear fitting,and the change law of friction coefficient between two rough surfaces is analyzed.Convert the braking conditions of the train,design the pin-disk friction and wear experiment to obtain the change rule and influence factors of the friction coefficient between the contact surfaces,use the weighing method to analyze the wear rate of the pin and pin-disk,and further study the friction and wear mechanism and wear competition relationship of the contact interface of the wheel and brake shoe.