A Parametric Study About Disc Brake Noise Based On The Finite Element Method

Comfortable with the people's demand on car and the increasing requirements of environmental protection, brake noise and vibration have more and more attention and study. The brake noise is a complex nonlinear dynamics problem.This thesis use finite element analysis software ANSYS to analysis the stability of the system and the impact of the work state parameters and material properties of parameters, from the frictional contact and the complex eigenvalue analysis theory, on a brake existing high-frequency brake vibration and noise, to get some measures for suppressing noise.First, establish the finite element model of all brake parts for finite element analysis so that obtain their modal parameters. Then join the friction coupling and contact between the friction surfaces of the brake disc and pad to establish the contact coupled finite element model based on frictional contact surface. Also forecast the tendency and unstable mode of the brake noise through the eigenvalue analysis of whole complex coupling model.Then in accordance with the mode synthesis, research all components'modal composition of the instability and the contribution of the various components' different modes on the unstable mode. There are some elastic modes in the system first 60 bands is close to the system instability mode 6788.1Hz,but most of the modal frequency and modal frequency instability of the system is so greatly different from the main mode. This shows that the simple analysis of components' mode and the viewpoint that the instability of the system is generated by resonance with the main mode frequency and it's similar is not perfect.The more important work is to build a brake finite element model more realistic condition by changing the coefficient of friction, braking force, damping, temperature parameters,etc,and analyze the impact of these parameters on system stability.According to the analysis:As brake power increases, the instability of the system is linear growth; as the temperature increases, the system unstable mode is reduced in the vicinity of 7KHz, but get some new unstable mode; high coefficient of friction will make the system unstable; with the increase of pad material damping loss factor, the unstable mode frequency of brake system is obviously decreased, and stability of the system is apparently improved. These conclusions provide a theoretical basis for making measures suppressing the brake vibration and noise.