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Excitation and Transfer Mechanism of Brake Judder
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English
Abstract
The excitation and transfer mechanism of brake judder was investigated in real operating conditions on the road. Monitoring brake parameters, especially the dynamic brake-disc geometry, during judder led to a profound understanding of the excitation mechanism. This dynamic brake-disc geometry changes virtually due to acting forces on wheel, hub and brake disc. This was found to add to brake-torque variations and thus judder.
The simultaneous measurement of accelerations along the transfer path from excitation to the driver's contact points and the development of a suitable method to analyse global and local system behaviour enabled a better understanding of the transfer mechanism. A comparison of the global transfer functions of three vehicles with similar front suspensions showed highly different judder sensitivities. An analysis of the causal dependencies was carried out using local transfer functions.
An evident interaction between excitation and transfer mechanism was found; the dynamic behaviour of the brake-disc influences knuckle vibrations and vice versa. This underlines the necessity to examine the total system including not only the brake but the suspension and steering system as well rather than to investigate single subsystems.
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Authors
Citation
Gassmann, S. and Engel, H., "Excitation and Transfer Mechanism of Brake Judder," SAE Technical Paper 931880, 1993, https://doi.org/10.4271/931880.Also In
References
- Eichhorn U. Engel H.G. Tiemann R. 1991
- Inoue H. Analysis of Brake Judder Caused by Thermal Deformation of Brake Disc Rotors 21st FISITA Congress Belgrad SAE Technical Paper 865131 SAE Warrendale 1986
- de Vries A. Wagner M. The Brake Judder Phenomenon International Congress and Exposition Detroit SAE Technical Paper 920554 SAE Warrendale 1992
- Engel H.G. Saame C. Bachmann T. Eichhorn U. Dynamic Behaviour of Brake-Disc Geometry as Cause of Brake Judder 4th International EAEC Conference Strasbourg 1993
- Pelargus D. Schmitt A. The influence of oscillations on the ride comfort of passenger cars - a study to correlate objective data with subjective perceptions 24th FISITA Congress London IMechE London 1992
- Tiemann R. Engel H.G. Flat surface test-stand for investigations on braking dynamics 4th International EAEC Conference Strasbourg 1993