Multi-Scale Simulation Of High Speed Dry Sliding Friction On Double Rough Surface

When the train is braking at high speed,the wheel treads and brake shoes will come into contact,and there will be violent sliding friction.Both the wheel tread and the brake shoe surface have micron-level roughness,so only a few micro-protrusions come into contact during the actual train braking process,the real contact area is much smaller than the nominal contact area.concentration of stress causes a "flash temperature" point when the temperature of the material is too high.in turn,the physical and mechanical properties of the wheel material deteriorate,the surface hardness and tribological properties of the wheel decrease,and the wear of the wheel tread increases.Studying the contact conditions in the sliding friction process from the mesoscopic scale can effectively predict the heat and force distribution of the contact surface,and provide a theoretical basis for improving the life of the wheel.Based on the fractal theory,the W-M fractal function is programmed and calculated to complete the establishment of two-dimensional and three-dimensional rough surface contours.analyze the changing laws of surface topography under different fractal dimensions.Based on the Herzt contact theory,the deformation mechanism of the asperity in the side contact state is analyzed.introduce the asperity grade and area density formula,and then obtain the prediction model of the real contact area and contact load of the entire three-dimensional rough surface.the prediction model was verified by finite element simulation.The coordinates of the points on the three-dimensional rough surface obtained are extracted,using Soildworks to construct a double-rough plane contact model at the mesoscopic scale,import it into Abaqus finite element analysis software,completed the thermo-mechanical coupling mesoscopic scale simulation of the high-speed dry sliding friction process of the double rough surface under different working conditions,obtain the distribution of transient temperature field and stress field on the rough surface during sliding friction,On this basis,analyze the influence of different surface morphology,sliding speed,environmental temperature and other parameters on the friction coefficient of the double-rough plane high-speed dry sliding friction process.Based on the W-M fractal function and using polar coordinates to establish a three-dimensional cylindrical double-rough contact surface at a macro scale,imported Abaqus software to complete the thermal-mechanical coupling simulation of the rotating dry sliding friction of the double rough cylindrical contact surface.Obtain the change rule of the surface temperature field with the increase of the number of cycles,and analyze the position and change rule of the maximum equivalent plastic strain.The research in this paper reveals the contact characteristics and friction characteristics of the surface asperities between the double-rough plane and the cylinder in the high-speed dry sliding state at the mesoscopic scale.It is of great significance to study the wheel-rail sliding friction and tread-brake shoe sliding friction of high-speed and heavy-duty trains.