Multi-Objective Optimization Design Of Surface Structure Of High-Speed And Heavy-Load Brake Disc

As a key component to ensure the safe operation of equipment,disc brakes are widely used in high-speed and heavy-duty braking situations of large equipment.During the braking process,the friction force of the contact surface between the brake disc and the brake pad does work to convert the mechanical energy into internal energy,which not only causes the brake disc to produce a higher surface temperature and thermal stress in a very short time,but also undergoes repeated stress cycles.Surface thermal fatigue failure occurs later.Therefore,starting from the improvement of the braking performance of the brake disc,the optimization design of the surface structure has important research significance.This thesis takes a large megawatt wind power brake as the research object,starting from improving the performance of the brake disc surface anti-deformation,heat dissipation,and fatigue resistance,and taking the brake disc surface flexibility,temperature and fatigue life as the optimization goals for multi-objective Through optimization analysis,a surface structure brake disc with improved performance was designed.The main research contents and results are as follows:(1)The thermal-mechanical coupling analysis finite element model of the brake disc was established to analyze the temperature field and stress field under high-speed and heavy-duty braking conditions,and to determine the deformation and stress requirements that need to be met under the thermal-mechanical coupling;The theoretical analysis of the surface temperature rise of the moving disc and the thermal-mechanical coupling analysis of the brake disc under different surface friction areas have determined the surface friction area requirements under a reasonable temperature rise;by establishing a finite element model for the fatigue analysis of the brake disc under the thermal-mechanical coupling,based on S-N curve method analyzes the fatigue damage and life of brake discs,and determines the minimum fatigue life requirements of the surface under high-speed and heavy-load conditions.(2)Based on the linear weighting method,the multi-condition optimization mathematical model of the brake disc surface braking process was established,and with the weighted flexibility as the optimization objective,the finite element model of the surface multi-condition flexibility optimization under the thermal and mechanical coupling was established.After optimization analysis,the surface weighted flexibility variation range is obtained;The optimization objective is to minimize the dispersion coefficient within the surface friction area range,and the surface friction area optimization finite element model is established.After optimization analysis,the variation range of the dispersion coefficient is obtained;The optimization objective is to maximize fatigue life,and the surface fatigue life optimization finite element model under the thermal and mechanical coupling effect is established.After optimization analysis,the surface fatigue life variation range is obtained.The above-mentioned parameter optimization results lay the foundation for the further establishment of a multi-objective optimization mathematical model.(3)Based on the average distance method,the optimization problem of multiple target parameters of different dimensions is transformed into a weighted minimization problem of relative distance.By establishing a surface flexibility-fatigue life multi-objective optimization finite element model,the optimization process and results of weight changes are analyzed,and select the reasonable weight coefficients of the multi-objective optimization mathematical model.On this basis,a mathematical model covering multiple optimization objectives of surface flexibility,temperature and fatigue life is established,and equal weighting coefficients are assigned to the three.Through multi-objective optimization analysis,the weighted surface flexibility is reduced by 16.03%,the surface temperature is reduced by 16.70%,and the minimum fatigue life of the surface is increased by 20.35%.Analyze the structural characteristics of the optimization result and reconstruct the surface structure,analyze the braking performance of the reconstructed brake disc,and all the parameters meet the design requirements of the optimization process.Through the multi-objective performance analysis and optimization design of high-speed and heavy-duty brake discs,this thesis provides a design scheme for the optimization of the surface structure of the brake discs,which has theoretical and practical significance for the study of improving the braking performance by using the surface structure.At the same time,it also provides a reference for the selection of multi-objective optimization methods.