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Automotive brake noise and vibration have been notorious as one of tough problems. Moreover, it becomes tougher along with stronger power of automobiles since the improved speeding performance should be possible only with larger braking force that causes higher heating and noise dissipation. Recent high-end brake kits have a tendency to adopt cross-drilled and slotted patterns to reduce disc temperature by obtaining additional functions such as air ventilation and cleaning friction surface; however, the effects of the patterns on squeal noise are not sufficiently understood.Many methods to identify brake noises have been presented. The squeal, as a typical brake noise, is an identified phenomenon, caused by dynamic instable self-excitation. Therefore, it may be defined as an elastic instability that is related to elastic modes of brake components, emitting audible frequencies. One of most common analytical methods for predicting squeal is the finite element method. The recent researches for squeal are focused on the relationship between in-plane and out-of-plane modes of a brake disk, squealing through coupling of in-plane circular and out-of-plane diametric vibration.This study investigates the effect of machining patterns cross-drilled and slotted on automotive disk brake squeal. Three different types of patterned disk brakes are tested to measure mode frequencies. The test results are compared with the finite element analyses and used to tune finite element models. The tuned FE models are parametrically studied by varying various designated design factors of radius, width and depth. As major results, the cross-drilled patterns are understood to make lower the frequencies of in-plane mode and the out-of-plane mode, while the slotting patterns are factors to reduce out-of-plane mode frequency and increase in-plane mode frequency.

Automotive disk brake; Squeal noise; Modal superposition; Brake friction surface pattern; Finite element method