Study On Friction Characteristics Of Grooved Brake Interface For High-speed And Heavy-load Disc Brake

Disc brake is the deceleration devices of many high-speed and heavy-load mechanical equipment.During emergency braking,it is easy to cause high-temperature deformation and severe wear of the friction pair.Therefore,it is great significant to improve the heat dissipation and wear resistance of the disc brakes.The grooved structure could change the geometrical appearance of the surface,and cause the change in the contact state of the friction interface,which has an important influence on the surface friction characteristics.In this research,the friction characteristics of the grooved brake interface of high-speed and heavy-load disc brakes were researched by the combination of thermal-mechanical coupling finite element simulation and friction wear experiment.The main research contents and results are as follows:(1)The braking process of high-speed and heavy-load disc brakes was analyzed.The groove structure with different geometric parameters was designed on the surface of the brake disc.According to the contact theory and heat conduction theory of the thermal-mechanical coupling process,the boundary conditions of the temperature heat conduction equation,thermal convection and heat conduction of the grooved disc brake were analyzed.Finite element model of the brake disc/brake plate was established and simulated.The effect of temperature and stress on the frictional heat generated by different angle,width and density grooved disc brakes was researched by single variable method.The results show that the grooved structure could reduce the temperature,stress value and the radial temperature gradient of brake disc surface;when the groove is angle 45°,width 4mm,quantity 4/disc,the brake disc temperature and stress value are the smallest.(2)The test method was used to calculate the test load according to the actual working condition of the disc brake,the friction wear test was carried out by using the pin disc friction pair.The influence of the groove angle and width on the friction coefficient,wear and surface morphology of the friction disc was analyzed.The results show that 45° groove friction disk has the lowest friction coefficient,wear and wear scar width;the smaller the groove width,the smaller the friction coefficient,wear depth and wear scar width of the friction disk.(3)The finite element simulation and friction wear experiments of different braking parameters of the grooved disc brake were carried out.The effects of initial speed and brake pressure on the temperature value,stress value,friction coefficient and wear depth of the grooved brake interface were analyzed.The results show that the larger of braking parameters,the more obvious the improvement of the groove on the brake interface;the larger initial rotation speed,the larger friction plate temperature and stress value,the smaller friction coefficient and wear depth;the larger brake pressure,the greater friction disk temperature,stress,friction coefficient and wear depth.(4)Based on the response surface optimization method,the experimental scheme was designed with groove angle,width and density as variables,and the temperature and stress of brake interface as response values.The sample data was obtained by thermal-mechanical coupling finite element simulation,the response surface was established and the fitting evaluation was performed.Taking the minimum temperature and stress values as the optimization goal,the penalty function optimization method was used to obtain the optimal solution,and the brake disc model was reconstructed and finite element analysis was carried out.The results show that the optimized temperature value and stress value of the grooved disc are reduced,the predicted value of the response surface is close to the simulation value,and the response surface method is suitable for the optimization of the groove geometry parameters.Based on the results of the thermal-mechanical coupling simulation and friction wear experiment of the grooved disc brake,it provides solution and theoretical basis for solving the problems of severe thermal deformation,severe wear and fatigue failure of the existing conventional disc brakes.