Dither Effect Of Drum Brake Squeal
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Date
2015-01
Authors
CHOE YUNG, TEOH
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Abstract
Vehicle brake squeal is a typical traffic noise pollution which is caused by friction induced vibration. The sound pressure level of the brake squeal is higher than 70 dB and it can cause hearing damage if long-term exposure. This thesis describes the use of high frequency excitation force for suppressing drum brake squeal, commonly referred to as dither control. A piezoceramic actuator is used to generate the dither force. The application of dither has successfully quenched the drum brake squeal from 85 dB to background noise level of 38 dB. A bi-axial two DOF mathematical model is developed to investigate the characteristic of drum brake squeal and the effect of dither on drum brake squeal at various operating parameters. The model parameters are defined based on the mobility measurement in both normal and tangential directions. This model is then validated with the measured results during squeal. The effectiveness of dither is investigated in four excitation frequencies in both tangential and radial directions. The numerical results show that dither control is more efficient in tangential direction and during low dither excitation frequency. Besides, at low sliding speed, lower dither force is needed to suppress the brake squeal. The predicted results based on the developed model shows high correlation with the measured results. The existences of dither excite the sidebands of the squeal peak with equal frequency spacing at both sides before complete suppression of the brake squeal.
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Keywords
Dither Effect Of , Drum Brake Squeal