Search Results

This work presents the modeling and investigation of the mechanical behavior of brake pad materials with high viscoelastic content, reinforced with particles and fibers. A simplified model is presented, with the purpose of prediction of the elastic modulus of this class of material. The model consists in the modification of the Rule of Mixtures, with the introduction of a term referring to the particle phase present in the composite material. It is introduced an alignment factor, in order to adjust the magnitude of orientation of the fibers in the stage of material compaction process. Also, the influence of the viscoelastic phase is modeled according to the percolation theory. Three standard brake pad materials with different viscoelastic contents were produced and tested. The composite materials produced were tested by three-point bending, in order to determine their mechanical properties.

In order to reduce brake squeal noise shims are really common proposition, however, to define whether a shim is good or not to fix a specific problem, only two things are considered: damping and the noise results obtained in dynamometers tests. In this paper it is presented the importance of the contact stiffness between the baking plate and the piston or caliper on the squeal noise generation and how the shim contributes improve this factor. A method to measure this property is presented as well the results obtained using this method, correlating the contact stiffness of a non-painted, painted and shim applied backing plate. In the end, we are showing how the brake pressure may influence the shim contact stiffness and consequently the noise generation.

It is widely known that a typical brake system works by mitigating vehicle kinetic energy and transforming it into thermal energy, ultimately leading to energy dissipation. The main concerns related to this kind of system are: 1) low frequency vibration energy propagating throughout the vehicle structure when the system begins its unblocking action; and 2) high frequency vibration energy propagation which induces undesirable noise levels. Modal analysis of the system can provide important information about its vibration characteristics. Provided that coupling between the dynamic behavior, the pre-stress caused by the applied load, and friction characteristics will certainly occur, it is required that analyses be performed on the entire assembly. As such, this paper presents evaluation of a brake disc system regarding the brake squeal using finite element method comparing with experimental assessment.