Thermal Coupling Digital Simulation Analysis And Friction Performance Of Nitrogen Carburizing Disc Brake

Disc brake is the executive part of automobile brake system,and brake disc is one of the core parts of brake.In the process of braking,the kinetic energy is converted into friction heat,which leads to the increase of the temperature of the brake disc and the thermal stress,which affects the braking performance.The N-C co-permeation brake disc is used to improve the surface performance of the traditional high carbon equivalent gray cast iron brake disc,and then improve its braking performance and operation life.In this paper,the microstructure,thermal stability and friction and wear properties of the nitrogen-carbon co-osmotic brake disc are studied based on simulation and experimental research.The main work and conclusions of this paper are as follows:(1)Numerical simulation and experimental verification of the thermal structure coupling of brakes based on ANSYSWorkbench software.According to the actual working conditions,the coupling finite element model and boundary condition setting of brake thermal structure are completed,and the variation law of brake disc temperature and stress with braking time during braking is analyzed,as well as the influence on the friction and wear performance of brake disc.The simulation results show that the brake disc has a ring temperature and high stress value region at the friction contact,the maximum temperature of the brake disc is 213.59? at the braking time 2.4 s,and the maximum stress field is 257.85 MPa..The experiment of residual stress measurement shows that the nitrogen-carbon co-osmotic brake disc can make the residual tensile stress produced by machining become smaller residual compressive stress and have higher fatigue strength.(2)Based on the microstructural analysis of the N-C co-permeation brake disc,the friction and wear experiments of each component layer of the N-C co-permeation brake disc were carried out by using the GCr15 cemented carbide ball as the matching pair.The friction behavior and wear mechanism of each component layer were studied by morphology observation.the wear resistance of diffusion layer is the best,the wear of compound layer is the worst,the wear form of compound layer is slight peeling wear,the wear form of diffusion layer is slight peeling wear and trisomy wear,and the wear form of matrix is slight adhesive wear with trisomy wear.With the increase of load,the wear forms of compound layer are spalling wear and trisomy wear,diffusion layer wear form is fatigue peeling wear,matrix wear form is serious adhesive wear and fatigue peeling wear and trisomy wear.(3)To study the thermal stability of the nitrogen-carbon coproosmotic brake disc under practical conditions.The experimental results show that the heat decay of the brake disc without nitrogen-carbon co-osmotic treatment is better than that of the brake disc without nitrogen-carbon co-osmotic treatment.(4)To study the friction and wear properties of the nitrogen-carbon coposmotic brake disc under actual working conditions.under the semi-metallic base friction pairings,the friction coefficient,the amount of wear,the wear surface and the three-dimensional morphology of the wear marks of the brake disc are measured based on the actual working conditions,and the friction and wear mechanism is analyzed.The results show that the friction coefficient of the brake disc is high and stable,and the wear resistance is good,especially under the condition of large load and long time,the wear form of the brake disc is slight oxide trisomy wear under low load,and the wear form under high load is fatigue peeling wear.