Vibration And Noise Of Air Disc Brake Research

With the rapid development of China’s automobile industry, the number of carproduction and ownership is developed quickly. Vehicle noise has become a majorsource of noise in the city. As requested by the relevant environmental regulationsand consumer raised drive comfort, brake noise has become one of the automotiveindustry need to be resolved.In this paper, on the basis of the relevant aspects of the Research brake noiseand brake noise suppression characteristic, method by the complex modal analysisand thermal-mechanical coupling is used and having the brake assembly noisestudy from the parts frequency coupling and the shape of friction pad on the air discbrake.The brake noise theoretical derivation is done in the paper and the relationshipbetween natural logarithm of vibration velocity and noise is linear. The coefficient offriction between the brake disc and the pad is one of the major factors has caused thebrake noise during braking through brake kinetic equation. Friction factor hasintroduced stiffness matrix and mass matrix of the brake assembly system resultingin an asymmetric system that causing system instability modes produced. the systemmodal characteristics of the imaginary part indicates that the modal frequencies arecorresponding to the system and the real part of the eigenvalues are correspondingthe modal degree of instability. For each mode of the braking system, if the modevalue of the real part characteristic is greater than zero, then it has a modalinstability tends to cause the brake system that can generate a brake noise.Each part of the brake assembly establishes a finite element assemble model(that includes brake disc, bracket, caliper, friction pad, the steel back of friction padand push plate) and has define the friction coefficient between the friction plate andthe brake disc and the contact coupling in the brake assembly surface, also connectsthe system that can complete the establishment of relations with the finite elementmodel of disc brake assembly. Through complex eigenvalues subspace projectionmethod can get complex eigenvalues of brake assembly systems, and by selecting aseries of friction coefficient which is between friction pad and brake disc can help to research the noise generated tendency of the brake assembly system.At last, a brake disc-friction pad of thermal-mechanical coupling model isestablished and determined the heat input and convective heat transfer boundaryconditions that treats brake bench test conditions as a benchmark, and thenperformed a braking test by finite element simulation analysis. The convective heattransfer coefficient between the brake disc and friction pad is influenced by thetemperature field and stress field with the speed of changing and the frictioncoefficient of friction pad is also influenced by temperature. By the condition canget the brake distribution of temperature and stress field. By Comparing thedistribution of stress field and temperature in different friction pad shapes can helpthe study on vibration and noise, and the corresponding which friction pad shapeshould be selected in the brake assemble system.