Suppression of Friction-Induced Oscillations through Use of High-Frequency Dither Signals

Vibration;Dither;Squeal;Brakes;Friction;Nonlinear

Michaux, Michael Andre ; Mechanical Engineering

University:Georgia Institute of Technology

Department:Mechanical Engineering

关键词: Vibration;    Dither;    Squeal;    Brakes;    Friction;    Nonlinear;   

Others  :  https://smartech.gatech.edu/bitstream/1853/7150/1/michael_michaux_a_200508_phd.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

Friction-induced oscillations occur in many engineering systems, often resultingin noise, vibration, and excessive or uneven wear. This research addresses thesuppression of such oscillations, especially with application to braking systems, throughthe use of high-frequency dither signals. Brake squeal is an annoying and elusive problemtoo often present in braking systems of automobiles, trucks and aircraft.In previous work, the effectiveness of high-frequency dither to eliminate squeal inan automotive disc brake assembly was demonstrated experimentally. The main featuresof the dither-squeal cancellation system was the application of a high frequency variationin the brake pressure force accomplished by means of a piezoelectric stack placed behindone of the brake pads.This thesis contains a theoretical and numerical treatment of the application ofdither to frictional systems. Two types of systems are investigated. The first is a classic,mass-on-a-moving belt problem, which experiences friction-induced oscillations similarto those encountered in brake applications. The system is first studied using an analyticaltechnique based on the method of averaging. It is shown that, depending on the system,friction, dither-waveform, and belt-speed parameters, dither can stabilize an unstablesystem. However, in some cases, dither can destabilize an initially stable system. Theseresults are verified numerically using time integration. The second type of systemanalyzed in this thesis is an annular plate with a rotating frictional device. The method ofmultiple scales is used to predict subcritical regions of instability; the results are validatedusing Floquet theory. The thesis treats both tangential and normal dither, the latter being closer to the brake application. It is found that normal dither, in addition to being harderto analyze, is much less effective than tangential dither.