Numerical Simulation And Analysis Of Disc Brake Noise

Along with the strict regulation of the vehicles noise laws, the measures that resolve the vehicles noise draws more attention by the automobile industrial world day by day. It is the substitution of asbestos friction material by metal friction material and the decreasing of structure mass that vary the structure dynamic stability and even worsen the problem of braking noise; The braking noise draw more and more attention, it becomes one of questions that the; company needs to solve urgently.The following has been finished.(1) With the actual working conditions simulated, the finite element vibration model of disc brake-shoe is established.And the vibration of brake-shoes in different viscoelasticity materials are analyzed by NATRAN.It is Proved that the damp dissipation factor of viscoelastic materials is an important factor influencing on brake-shoe's vibration amplitude, model frequency and vibration energy.This indicates that the application of damp technology in reducing braking vibration and noise is feasible.(2) By experiment of disc brake-shoe material, it proved the damp dissipation factor of viscoelastic materials is an important factor influencing on brake-shoe's vibration amplitude.(3) In this paper, we established a 3D finite element model of a vehicle disc brake system which includes a brake disc. 2 pads. In the model, the friction force leads to asymmetric stiffness coupling,A commercial finite element software was applied to solve the complex eigenvalues of the motion equations of the model. If the real part of a complex eigenvalue is positive, the corresponding mode is unstable, which may result in squeal. The influences of the friction coefficient are discussed.(4) When brake squeal occurs, the modes of the disc brake system are characterized by mode coupling. Namely, some neighboring modes with close frequencies may merge when friction coeficient varies. In the merging points, the real parts of the corresponding complex eigenvalues are positive.In the case, the brake system has a propensity of squeal occurrence.The coefficient of friction has a heavy influence on occurrence of brake squeal. With the friction coefficient increasing, the real part values of the complex eigenvalues of coupling modes increase and more modes with positive real parts arise.That shows that the propensity of squeal occurrence will increase.(5) A finite element model of the brake system is built, and the instantaneous response analysis of brake disc is done. We get the vibration velocity of node of the brake disc surface.By FFT.we get the velocity boundary condition of the brake disc surface. Then by building a meshing model of the brake disc,Boundary element methods are used to calculate acoustic radiation of the brake disc, which provides the theoretical direction for decreasing noise.