Study On The Occurrence Trend Of Braking Noise Of Train Disc Brake Based On Finite Element Method

Brake noise will not only affect the comfort of passengers in the train,but also affect the life of residents along the railway.The research on brake noise has attracted more and more attention.The research on brake noise source is of great significance to noise control and noise reduction in the process of braking.This paper first introduces the types of train braking and its key braking components,and then brings to the mechanism of brake noise and the factors affecting the brake noise.From the species of brake noise,the vibration frequency of brake noise is concentrated between 10-16000 hz.As the main source of train braking noise,disc brake is the braking force formed by friction resistance,and the friction noise between brake disc and brake pad is the focus of this paper.In this paper,a model of axle mounted brake disc and brake pad is established,in which the brake disc is equipped with cylindrical heat dissipation ribs and 18 friction blocks with holes are distributed on the brake pad.Firstly,the modal analysis of the brake disc and the brake pad is carried out in the free state,and the natural frequencies and vibration modes of the brake disc and the brake pad are obtained.Combined with the modal coupling theory,the frequencies and vibration modes of the brake disc and the brake pad are analyzed,and the frequencies of the brake disc and the brake pad prone to noise are predicted from the natural attributes.Then,according to the actual braking process of the brake mechanism,the constrained modes of the brake disc and brake pad assembly are analyzed,and the natural frequencies and vibration modes of the assembly are obtained.Combined with the results of free mode analysis,it is found that the higher the vibration frequency is,the more the pitch diameter is,the stronger the mode coupling phenomenon is.Then,the complex eigenvalue analysis of the brake disc and brake pad assembly is carried out under different working conditions by using the fully nonlinear perturbation analysis method,and the real part value of the frequency within 16000 Hz is extracted.The positive real part corresponds to the unstable state of the system,which is likely to produce noise.Using this method,the influence of friction coefficient,pressure and elastic modulus on braking noise is studied by controlling variables.It is found that the change of friction coefficient has the most obvious effect on the real part,and the value of real part will increase with the increase of friction coefficient,and the increase amplitude is the largest under high-frequency vibration,corresponding to the brake noise,the change of friction coefficient will increase the probability of noise generation;while the brake pressure has little effect on the real part,mainly in the high-frequency vibration stage,which indicates that the brake pressure has great influence on the real part,the influence of noise is mainly concentrated in the high-frequency stage;the paper also analyzes the influence on the noise by changing the elastic modulus of the brake disc,and finds that increasing the elastic modulus of the brake disc will reduce the number of real parts,which indicates that the proper selection of materials with larger elastic modulus can reduce the noise.