Disc Brake Vibration Noise Study And Research Based On ANSYS

With the rapid development of Chinese enconomy, vehicles have used by ordinary people's families and given more convenience to people's life and work. Now customer's expectations for new vehicles are not only high safety and low price, but aslo high comfortableness, such as low vibration noise. With the development of automobile technology, the noise and vibration of the whole vehicle are decreased very much, but the vibration noise of the parts and subsystems such as brakes becomes more and more prominent. So the rearch on vibration noise in brakes are more important than before, its results will be valuable for the structure design of brake.In this thesis, the principle of finite element and several common softwares of finite element analysis are introduced firstly, and then some type of the car made by Chinese company have been taken for example. Though simplified calculation, it is supposed that the distribution of the braking moment is uniform, then the braking moments of its disc, block and anchorage are determined. For establishing the CAD model of the components of the brake, the grid division of the model are taken into account, and those unimportant concaves and fillets are also overlooked.By means of the mapped method, the appropriate boundary conditions and degrees of freedom for the established model grid are determined. Meaningwhile, the braking moment will be loaded on the finite element model for the mode and structure analysis.The results showed that when the natural frequency of brake disc is between 368～699Hz; the dynamic stiffness of brake disc is not enough, there is stress concentration at the sharp angles of the brake block; the dynamic stiffness of the brake anchorage is deficient. When there is the coincidence phenomenon of the frequencies of the different steps for brake parts, the resonant phenomenon will occur. For reducing vibration noise of the brake, the frequency will be reduced by means of some methods such as changing the thickness, making fillets at the sharp angles and opening the ventilations at the brake disc.The design model optimized is put in ANSYS, the modal analysis is made again, its results shows that situation of stress concentration is improve tremendous and the natural frequencies of various components have been increased. Because the external excitative frequency is generally very low, the coincidence phenomenon of different frequency bands has been also improved. These methods decrease the vibration noise effectively. This improvement method will be tested further.The significance of this thesis is to present the method of analyzing the reasons of brake vibration noise by means of the modal analysis principle. This method applies not only to the noise detection for the brake, but also to the noise detection for the mutual coupling components in machinery industry, and it will provide a new method for the noise detection in engineering.