Creep-groan is an intense low frequency vibration and noise phenomenon commonly experienced in passenger cars fitted with an automatic transmission and disk brakes. It can be provoked when the driver allows the car to creep forward using only light pressure on the brake pedal and it causes an intense low frequency noise both inside and outside the car. This paper describes the results from a suite of recent experiments aimed at first understanding and then mitigating the problem. The cause of the vibration is shown to be a stick-slip relationship between brake disk and brake pad. The stick-slip relationship is investigated in a study of the difference between coefficients of static and dynamic friction on a full-scale laboratory rig, and using a particular form of vibration analysis, the influence that the brake, suspension and steering system dynamics have on the character of the creep-groan is discussed. The use of a novel method for measuring the distribution of brake force across the surface ofthe brake pad is introduced. The vibration path from the on-car brake disk to the occupant's ear is discussed. Finally, proposals for controlling creep-groan noise and vibration are discussed.
Low-frequency vibrations in disk braking systems - controlling the creep-groan phenomenon in road vehicles
Niederfrequente Schwingungen in Scheibenbremssystemen - Abminderung von Kriech-Brumm-Geräuschen in Straßenfahrzeugen
2004
9 Seiten, 7 Bilder, 10 Quellen
Conference paper
English
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