Research On Structure Optimization Of High-Speed And Heavy-Load Brake Disc Based On Coupling Of Friction-Thermal-Vibration

Disc brakes have many advantages such as reliable braking,simple structure,easy maintenance and fast heat dissipation,which are widely used in high-speed and heavy-load equipment such as aerospace,high-speed trains,wind power generation,and large construction machinery.The high-speed and heavy-load disc brake process is a complex friction,heat and vibration multi-physics coupling process.Under the complex coupling of multiple physical fields,as a key part of the disc brake,the brake disc has serious problems of friction and wear,thermal damage of the disc body and disc surface,and brake vibration under dynamic operating conditions,which seriously affect the braking performance of the disc brake and the safety of high-speed and heavy-load equipment operation.Therefore,it is of great significance to study the mechanism of high-speed and heavy-load braking mechanism based on friction-thermal-vibration multiphysics coupling,and to optimize the brake disc structure on this basis.In this thesis,by studying the mechanism of high-speed and heavy-load braking under the coupling of friction-thermal-vibration multiphysics,and focusing on the performance requirements of high-speed and heavy-load braking conditions on the brake disc,the optimization methods of the internal and surface structure of the brake disc are proposed.The internal and surface structures of high-speed and heavy-load brake disc suitable for friction-thermal-vibration multiphysics coupling conditions are optimized.The main research contents and research results of this thesis are as follows:(1)According to the braking mechanism of high-speed and heavy-load disc brakes,a multi-physical coupling analysis method of friction-thermal-vibration is proposed.multi-physical coupling analysis model under three load modes of force-temperature-displacement is established by using the data related to the vibration of the brake disc in the multi-flexible body dynamic analysis results of the disc brake as input.The model is verified by the inertia test of shrinkage ratio to obtain the distribution law of temperature field and stress field of the brake disc under the coupling of friction-heat-vibration multiphysics,revealing the coupling of friction-heat-vibration multiphysics high-speed and heavy-load braking mechanism.Based on the performance requirements of high-speed and heavy-load braking conditions on the brake disc,the optimized area of the brake disc aer divided.(2)Aiming at the characteristics of high-speed and heavy-load brake discs subjected to moving loads,a structural topology optimization method based on equivalent moving loads is proposed.With the optimization object of minimizing static flexibility and maximizing dynamic frequency under coupling effect,an optimization model of the internal structure of the brake disc based on moving load is established.The influence law of the number of brake pads installed on the internal structure of the brake disc is analyzed,and the coupling effect of static flexure,dynamic frequency,friction-thermal-vibration multi-physics on the internal structure of the high-speed and heavy-load brake disc As a result,the internal structure of the constant velocity spiral centrifugal high-speed and heavy-load brake disc with minimum static flexibility and maximum dynamic frequency is obtained.(3)Aiming at the performance requirements of high-speed and heavy-load braking conditions on the brake disc brake interface,a surface topograhy optimization method that can globally control the displacement and stress generated on the surface of the high-speed and heavy-load brake disc is proposed.Through the brake interface friction and wear test,its structure is selected in terms of friction heating,friction coefficient,wear degree and vibration performance.A multi-objective optimization model of the brake disc brake interface for displacement and stress control is established.The effects of static load,temperature load and frequency target constraints on the structure of the brake interface are analyzed through the optimization results.A radial uniformly distributed high-speed and heavy-load brake disc brake interface with improved brake interface rigidity,increased frequency,and ability to accommodate abrasive debris is obtained.(4)Based on the optimization results of the internal and surface structure of the brake disc,combined with the workability,the optimized brake disc is reconstructed.Aiming at the optimized braking performance of high-speed and heavy-load brake discs,the vibration characteristics,friction-thermal-vibration multiphysics coupling characteristics simulation analysis and reduced inertia brake test comparison verification are carried out.Verification results show that the optimized brake disc has better surface deformation,temperature,and stress distribution under the high-speed and heavy-load braking conditions than the unoptimized brake disc.And under different initial speeds and different braking pressures,the friction coefficient of the optimized brake disc is more stable and the braking time is shorter.The above research work has important theoretical and practical significance for improving the design and manufacturing level of high-speed and heavy-load brake discs and promoting the rapid development of high-speed and heavy-load brake technology in China,and for enriching other multiphysics coupling analysis theories and multiphysics The structure optimization method and engineering application under the field coupling have certain reference significance.