A Study On Disc Brake Noise

With the development of automobile industry,brake squeal has been widely concerned.But due to its mechanism and complexity factors,brake squeal has become a difficult issue for automakers.In order to solve the actual brake squeal,this thesis studies analysis methods of disc brake squeal both at home and abroad.Based on the closed-loop coupling model theory,a whole brake squeal analysis model of target brake is established.Different from the finite element simulation,this model avoids complex contacts and friction between components.The method to suppress braking squeal is studied from the perspective of finding the key structural dynamic parameters that affect braking squeal.and brake squeal in actual disc brake is solved successfully.In this thesis,the modeling process of target brake squeal analysis model is described in detail;Finite element models of all the parts of brake are established.And through the contrastive analysis of modal test and simulation computation,the material parameters are confirmed and the accuracy of finite element model is verified.Then several finite element models are combined into substructure models,and the model parameters reflecting the dynamic characteristic are calculated;The coupling parameters are determined by analyzing the coupling relationship between substructure models,then the coupling stiffness matrix of different coupling interfaces is derived concretely;In particular,a new method for surface coupling is proposed.The complex eigenvalue analysis of the target brake is carried out by using the closed-loop coupling model established,and the complex characteristic roots representing the degree of stability are obtained.The analysis results are in good agreement with the brake test results;Meanwhile based on the established brake model,the influence of friction coefficient,brake speed and elasticity modulus on the system instability is discussed;The structural factor which has the greatest influence on 1600 Hz unstable mode is found by using the analysis methods of substructure modal composition coefficient analysis and sensitivity analysis,and a suppression scheme of modifying brake squeal is proposed;The test results of brake bench after adopting the modification scheme show that the frequency of brake squeal with sound pressure level greater than 70 d B is reduced by about 90%,which proves the effectiveness of the proposed modification scheme.The research work in this thesis is a complete successful example to solve the disk brake squeal,which has a good reference value to solve similar engineering problems.