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Self-Excited Vibrations During Engagements of Dry Friction Clutches
ISSN: 0148-7191, e-ISSN: 2688-3627
Published November 16, 1998 by SAE International in United States
Annotation ability available
Event: International Truck & Bus Meeting & Exposition International Truck & Bus Meeting & Exposition
During the starting of the vehicle, the friction clutch engagement sometimes generates judder. Judder prevents vehicles from starting smoothly, harms the ride comfort, and may produce damage to the drivetrain components. This unpleasant phenomenon, which often manifests in the form of noisy torsional vibrations of the drivetrain or a violent surging of starting vehicles, is an example of the many annoying problems that automotive engineers have been experiencing since the car was invented.
Engineers and scientists have identified some causes of transient torsional oscillations connected to judder. Vibrations generated by the clutch facings when a special type of relationship between the friction coefficient and sliding speed occurs account for the most important source of judder. Other potential judder sources are: misalignments in the drivetrain that may induce fluctuating pressure between sliding components, some thermoelastic phenomena on contact surfaces, and/or torsional excitations from the engine and universal joint in the presence of special resonant conditions.
The present paper concentrates on a research of selfexcited vibrations that are generated by a special type of friction force identified by an increase of the coefficient of friction on clutch facings when the slip speed on friction surfaces decreases. The self-excited vibrations are very interesting nonlinear phenomena. The amplitude of selfexcited vibration depends on the system parameters alone. It does not depend on the initial energy or initial conditions.
The ultimate goal of the present research was to develop a reliable mathematical model for the dry clutch engagement to allow the easy engineering analysis and design of engagement for various facing materials and drivetrain configurations. The reliability of the model was to be assured by a strict correlation of the simulation with experimental results.
The first basic task of the present paper was to model experimental engagements performed on a facing dynamometer that is commonly used in the automotive industry. The mathematical description, both qualitative and quantitative, was corroborated and repeatedly adjusted by extensive testing. The final model was used to study the behavior of various existing and hypothetical facing materials in dyno testing. Some selected results of this study are presented.
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CitationBostwick, C. and Szadkowski, A., "Self-Excited Vibrations During Engagements of Dry Friction Clutches," SAE Technical Paper 982846, 1998, https://doi.org/10.4271/982846.
SAE 1998 Transactions - Journal of Commercial Vehicles
Number: V107-2; Published: 1999-09-15
Number: V107-2; Published: 1999-09-15
- Zagrodzki P. Influence of Design and Material Factors on Thermal Stresses in Multiple Disc Wet Clutches and Brakes SAE Trans., J. Commer. Veh. 100 911883 1991 395
- Bauld, N.R. Mechanics of Materials Second PWS Publishers Boston 1986
- Harris, C.M. Shock & Vibration Handbook Third McGraw-Hill Book Company 1988
- Den Hartog, J.P. Mechanical Vibrations Fourth McGraw-Hill Book Company 1956
- Smith, J.G.M. Wolford, J.C. Whaley, P.W. Vibration of Mechanical and Structural Systems with Microcomputer Applications Harper & Row Publishers New York 1989
- Miller, R.K. Introduction to Differential Equations Prentice-Hall, Inc. New Jersey 1987
- Rao, S.S. Mechanical Vibrations Second Addison-Wesley Publishing Company 1990
- Spiegel, M.R. Applied Differential Equations Third Prentice-Hall, Inc. New Jersey 1981
- Stoker, D. Nonlinear Vibrations in Mechanical and Electrical Systems Second Interscience New York 1950
- Timoshenko, S. Mechanical Vibrations Third D. Van Nostrand Co. New Jersey 1955
- Szumniak, J. Zagrodzki, P. Influence of Friction Composite Properties on Thermoelastic Instability in Brakes and Clutches Polish Scientific Committee for Scientific Research 1992
- The MathWorks, Inc. MATLAB Natick MA 1996