| The drum brake is a driving brake widely used in various vehicles,which is composed of brake drum,brake shoe and friction lining.Unreasonable structural design will cause an unstable state during the working process,and the resulting severe vibration will produce highfrequency howling.This noise will not only affect the comfort of passengers,but also pollute the urban environment.Therefore,this paper takes the drum brake as the research object,and proposes a scheme to suppress the braking noise based on the analysis of the mechanism and influencing factors of the brake squeal.Firstly,based on the structure and working principle of the drum brake,the threedimensional model is simplified and the vibration model of the contact unit is constructed.The friction coupling makes the system stiffness matrix asymmetric,resulting in the solution of the dynamic equation to generate complex eigenvalues.When the real part of the complex eigenvalue is greater than zero,the system is in an unstable state.Based on the above theory,a nonlinear finite element model of friction contact with brake drum,brake shoe and friction lining is established in ABAQUS.Secondly,the complex modal analysis method is used to predict the brake squeal,and the instability of the system is predicted according to the positive value of the complex modal real part.The influence of different factors on brake squeal was studied by changing friction coefficient,braking pressure,braking speed,elastic modulus,damping and temperature.The partial factor design method was used to explore the change trend of the tendency of instability under the interaction of multiple factors,with the nonlinear factors friction coefficient,braking pressure,elastic modulus of friction lining and elastic modulus of brake drum as design variables,and the tendency of instability as response value.Finally,workbench is used to optimize the parameters of friction lining chamfering and thickness,and the optimized model is verified by complex modal analysis. |
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