Analysis Of Characteristics Of Aircraft Brake Squeal And Vibration Reduction Measures

Brake squeal has been a difficult and significant issue in the academic field.Especially for the aircrafts,the noise generated by the brake squeal will seriously affect the comfortability of passengers.However,the experiments of brake squeal of aircraft brake systems require high costs and long operating time.Therefore,the using of FEM in prediction of the squeal frequency,as well as the mechanism study and reduction of brake squeal,shows great advantages: 1.reducing the noise pollution during breaking 2.satisfying the passenger comfortability requirements 3.accelerating the design progress of lading gears.A corresponding finite element model is established according to a simplified aircraft disk brake system and its unstable modes are predicted by complex eigenvalue analysis and transient dynamic analysis in ABAQUS(commercial software).A couple of unstable modes are predicted by complex eigenvalue analysis.In the meanwhile,the results of transient dynamic analysis show that the axial motion of the brake system is the main form of brake squeal.Influencing factors of brake squeal have been analyzed by complex eigenvalue analysis in ABAQUS.The analysis results show that friction coefficients,friction damping as well as brake stress have obvious effect on brake squeal.Comparing the results of modal analysis of rotors and stators with aircraft brake system,we find that the coupling between rotors and stators is the fundamental factor of brake squeal.Two methods including adding free damping layer and modifying the shape of stators(groove and chamfer)are proposed and the theory of reducing vibration and noise is introduced.By comparing the complex eigenvalue analysis results of these two methods,we find that the method of adding free damping layer is a more feasible and efficient way to restrain aircraft brake squeal.