One of the fatigue tests used for friction materials is the so called “bump test”. In this test, one of the reaction disks in a pack of disks has machined bumps across the contact surface. These bumps generate locally high contact pressure and temperature. In this way, severe contact conditions like that arising in service can be reproduced. The major difficulty in utilizing the “bump test” is estimation of the local pressure and temperature. In this paper, a model is developed and experimental verification of thermoelastic contact is presented. The model represents a multi-surface contact problem for a pack of disks. Due to the presence of bumps, contact surfaces are not conforming. To solve this strongly nonlinear contact problem, a robust finite element code is used. The model also includes thermal effects generated by frictional heating. The coupled elastic contact and thermal problems are solved sequentially. Contact pressure at interfaces is measured in static conditions (without sliding) using pressure sensitive film. Good agreement between the model and the measurement is observed in sense of contact length and magnitude of pressure. In order to verify the full thermoelastic model, the transient temperature inside one of the disks is measured by thermocouples. The results agree with model predictions. The study shows that the local contact pressure is an order of magnitude higher than nominal pressure. Also temperatures are much higher than that predicted for uniform contact conditions. The developed model helps to understand complex thermoelastic effects accompanying the test and to control the test parameters.
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e-mail: wzhao@raybestosproducts.com
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January 2001
Technical Papers
Study of Wet Friction Material Test Under Severe Thermal and Mechanical Loading (“Bump Test”)
Wenping Zhao,
e-mail: wzhao@raybestosproducts.com
Wenping Zhao
Technical Center, Raytech Composites, Inc., 1204 Darlington Avenue, Crawfordsville, IN 47933
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Przemyslaw Zagrodzki
Przemyslaw Zagrodzki
Technical Center, Raytech Composites, Inc., 1204 Darlington Avenue, Crawfordsville, IN 47933
Search for other works by this author on:
Wenping Zhao
Technical Center, Raytech Composites, Inc., 1204 Darlington Avenue, Crawfordsville, IN 47933
e-mail: wzhao@raybestosproducts.com
Przemyslaw Zagrodzki
Technical Center, Raytech Composites, Inc., 1204 Darlington Avenue, Crawfordsville, IN 47933
Contributed by the Tribology Division for publication in the ASME JOURNAL OF TRIBOLOGY. Manuscript received by the Tribology Division February 11, 2000; revised manuscript received August 1, 2000. Associate Editor: M. D. Bryant.
J. Tribol. Jan 2001, 123(1): 224-229 (6 pages)
Published Online: August 1, 2000
Article history
Received:
February 11, 2000
Revised:
August 1, 2000
Citation
Zhao, W., and Zagrodzki, P. (August 1, 2000). "Study of Wet Friction Material Test Under Severe Thermal and Mechanical Loading (“Bump Test”) ." ASME. J. Tribol. January 2001; 123(1): 224–229. https://doi.org/10.1115/1.1331056
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