Mechanism Analysis And Optimization Of Automobile Brake Squeal Based On Contact Overlap Degree

With the rapid development of social modernization and automobile industry,people gradually choose the car as a travel tool,and the requirements of car comfort and safety are gradually higher.Among them,the noise problem of automobile braking system will not only bring great trouble to passengers,but also affect the safety of the braking system.Therefore,the research on the noise of automobile braking system is of great significance.Based on the solid floating caliper disc brake of a passenger car,the three-dimensional model and finite element model are established,and the complex modal analysis and bench test are carried out to verify the effectiveness of the finite element model.Combined with the previous research on brake noise,the mechanism of "contact weight" is put forward,that is,the influence of the coincidence degree of brake disc pad friction contact on the brake noise.By building the brake analysis model with vertical spring distribution,the key influencing factors of contact weight are selected and the complex modal analysis is carried out.The structure of the brake parts is improved by analyzing the asymmetry and non-uniformity of the contact weight.Finally,the response surface method is used to comprehensively analyze and optimize the influencing factors,which greatly reduces the tendency of brake squeal in the brake system.Firstly,the three-dimensional model of the brake is established,and the finite element model is built in the finite element software ANSYS / workbench.The finite element model of the braking system of the reference scheme is set and the complex modal analysis is carried out.The bench test with the same parameters as the reference scheme is carried out on the noise test bench.The effectiveness of the finite element model of the braking system is verified by comparing the results of the bench test and the simulation results of the complex modal analysis.Secondly,the concept of "Contact overlap degree" is proposed,and the influencing factors of braking noise are analyzed based on this mechanism.The key factors of brake squeal are selected as friction coefficient,brake pressure and elastic modulus of brake disc.The complex modal analysis of key factors is carried out by changing the established finite element model to determine the influence on the stability of brake system.Thirdly,by analyzing the asymmetry and non-uniformity of contact weight distribution,the structure of parts is improved.Based on the asymmetry of contact weight,the structural design scheme of the brake back plate is designed,which makes the distribution of brake pressure on the brake back plate more uniform and reduces the tendency of brake noise;Based on the non-uniformity of contact weight distribution,the structure of the friction lining is designed,which makes the force of the brake friction lining more uniform in the direction of friction,and is conducive to reducing the braking noise;The effectiveness of the improved structure is verified by the complex modal analysis of the finite element model.Finally,the most important factor affecting the stability of the braking system is selected for response surface optimization design.The friction coefficient,the elastic modulus of the brake disc and the angle of the friction lining groove are selected as the design variables,and the instability coefficient of the brake system is selected as the response value.The optimization scheme of three factors and three levels is set to find the corresponding design variables to minimize the instability coefficient.By solving the quadratic response surface function of response surface,the best optimization scheme is selected,and the response surface optimization scheme is verified by complex modal analysis.Finally,the tendency of brake squeal is reduced from 23.54 to 10.85,which greatly reduces the probability of brake squeal.