Date of Award
Master of Science
The main objective of this research is to address the relationship between formulation of friction lining materials and their propensity to friction induced noise generation. The basic idea was formulated earlier by Dr. Filip, who showed that the friction layer plays the relevant role when noise is observed during braking. It was shown that when newly formed patches (parts of the friction layer) exhibit a large difference in the coefficient of friction, brake lining is stretched and released repeatedly, which leads to significant vibrations and corresponding noise when coupled with the vibration mode of the system. Farhang ,on the other hand, demonstrated that noise can be related to specific surface roughness parameters and when properties of friction lining and friction layer (such as compressibility, stiffness and modulus of elasticity) fit into certain specific value ranges, noisy behavior occurs. This research will address the braking related to friction induced noise in relation to the properties of the bulk lining material and the character and properties of the friction layer. The friction tests will be performed using the CAFS-developed (Szary and Lee) real time noise measurement system compatible with the major part of SAEJ2521 standard (note that the system does not allow for reliable measurement of frequencies lower than 900 Hz). The mechanical properties of fourteen samples will be investigated. Of the fourteen samples, friction layer of three of the samples will be investigated by several analytical techniques developed by Dr. Filip . They include polarized light microscopy, scanning and transmission electron microscopy equipped with energy dispersive microanalysis, and X-ray diffraction. This research summarizes data from the J2521 dynamometer test of the Dodge Caravan samples exhibiting specific compressibility, porosity and hardness. Also, this research provides the results of friction surface analysis by SEM with energy dispersive microanalysis, light microscopy, surface roughness, and X ray diffraction. Of the fourteen samples, Bendix has the largest occurrence of noisy braking. Based on techniques developed by Dr. Filip, the characteristics of the friction layer strongly influence brake noise propensity. The friction layer characteristics are dependent on brake formulation. As predicted, "noisy stop" and "quiet stop" samples exhibit completely different friction surfaces.
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