The Study On Brake Noise And Structure Optimization Of Disc Brake

In recent years,the safety and reliability of automobiles have reached a very high level,but braking noise will be generated when the automobile brakes,which seriously affects the riding environment in the vehicle.Therefore,improving the comfort of cars,reducing braking noise,and improving the riding environment have become the common pursuit of consumers and car manufacturers,and have become the research topics of many scholars.In the brake system of automobiles,disc brakes are widely used for their advantages of mature technology,simple structure,stable performance and long service life.However,during the use of the disc brake,the brake discs and brake pads will modally couple with similar modalities of other parts,resulting in braking noise,which seriously affects the driving experience of the car.The study found that the natural frequency and vibration mode of each component can be obtained by modal analysis,and then the unstable modal of the brake can be obtained by the complex modal analysis method,and the parameters of the geometry structure that has a greater impact on the stability of the brake can be found,and on this basis,the modal characteristics of the structure are changed by changing the geometric parameters of the structure in the early stage of the design,so that the braking noise can be effectively reduced in the product development stage.Therefore,in order to reduce the instability of the brake and suppress the generation of brake noise,this paper uses the finite element theory to obtain the modal characteristics of each structural component of the brake,and studies the influence of changes of the geometric characteristic parameters of the brake pad on the brake instability,and optimized the brake structure.The main results are as follows:(1)Select the left front wheel brake disc of a medium-sized luxury car as the modeling prototype,perform three-dimensional modeling according to the actual size of the brake disc and block,and obtain the brake speed and brake pressure during the process according to the actual running state of the wheel during braking and related theoretical calculations.Determine the load and boundary conditions of each component during the analysis accordingto the actual load of each component during braking.(2)Perform constrained modal analysis on the brake assembly and each component.The bending and torsion modes of the brake pads and the circumferential modes of the brake disc and brake assembly are selected as the research objects.The results show that the brake may have modal coupling in various frequency bands,which leads to system instability.Among them,the number of unstable modals in the frequency range of 8000 ~ 15000 Hz is the largest,and the possibility of brake noise is also greater.(3)Complex modal analysis was performed on brakes with different brake pad characteristic parameters,and the influence of brake pad geometric characteristic parameters on brake stability was studied.The analysis results show that changes in brake pad thickness and groove depth have a greater impact on the stability of the brake.Reducing the thickness and increasing the groove depth can reduce the brake instability.(4)By analyzing the impact of changes in the size of the brake pad structure on the instability of the brake,the structural size that has a greater impact on the brake noise is selected-the depth of the groove of the brake pad as the optimization variable,and the response surface method is used to brake The block performs structural optimization with the goal of reducing instability.The groove depth of the optimized brake pad is 5.2 mm.Complex modal analysis is performed on the optimized brake again.The results of complex modal analysis of the optimized brake and the original size brake are compared.The results show that the number of unstable modes of the optimized brake is reduced,the real part of the complex eigenvalue of the unstable mode is significantly reduced,and the stability of the brake obviously improved,greatly reducing the probability of braking noise,and achieve the purpose of optimizing the brake.