This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Analysis of Temperatures and Stresses in Wet Friction Disks Involving Thermally Induced Changes of Contact Pressure
Annotation ability available
Sector:
Language:
English
Abstract
Thermal distortions of friction disks caused by frictional heating modify pressure distribution on friction surfaces. Pressure distribution, in turn, determines distribution of generated frictional heat. These interdependencies create a complex thermoelastic system that, under some conditions, may become unstable and may lead to severe pressure concentrations with very high local temperature and stress. The phenomenon is responsible for many common thermal failure modes of friction elements and is known as frictionally excited thermoelastic instability (TEI).
In the paper, one of the cases of TEI is investigated theoretically and experimentally. The study involves a two-disk structure with one fiction disk and one matching steel disk that have one friction interface.
An unsteady heat conduction problem and an elastic contact problem are modeled as axisymmetric ones and are solved using the finite element method. The model allows for investigation of thermally induced changes in contact pressure and accompanying temperature and stress fields. The solutions are calculated for real scenarios of clutch engagement recorded in stand tests. In those tests, transient temperatures at mid-radius of the friction surface are measured using a thermocouple. Also time courses of sliding speed, applied force and torque are recorded.
Theoretical solutions show specific behavior of the steel disk in the case when sliding occurs on only one side of the disk, leading to high contact pressure in the central part of the friction surface. These predictions are confirmed by experimental tests, which show temperatures at this location higher than the estimated mean temperature of the surface.
Recommended Content
Citation
Zagrodzki, P. and Farris, T., "Analysis of Temperatures and Stresses in Wet Friction Disks Involving Thermally Induced Changes of Contact Pressure," SAE Technical Paper 982035, 1998, https://doi.org/10.4271/982035.Also In
References
- Barber J.R. “Thermoelastic Instabilities in the Sliding System of Conforming Solids,” Proc. Roy. Soc., Series A312 1969 381 394
- Anderson A.E. Knapp R.A. “Hot Spotting in Automotive Friction Systems,” Wear 135 1990 319 337
- Lee Kwangjin Dinwiddie R.B. “Conditions of Frictional Contact in Disk Brakes and their Effects on Brake Judder,” SAE Technical Paper 980598 1998
- Du Shuqin Barber J.R. Zagrodzki P. Hulbert G.M. Thermoelastic Instabilities in brakes and Clutches 2nd International Symposium on Thermal Stresses Rochester, New York, USA June 8-12 1997
- Zagrodzki P. “Analysis of thermoelastic Phenomena in Multidisk Clutches and Brakes,” Wear 140 1990 291 308
- Zagrodzki P. “Influence of design and material factors on thermal stresses in multiple disc clutches and brakes,” SAE Transactions 1991 Paper 911883
- ABAQUS/Standard, User's Manual Hibbit, Karlsson & Sorensen, Inc.
- ASM Metals Handbook American Society for Metals Metals Park, OH 9th 1981 1 641 644
- Kennedy F.E. “Thermal and Thermomechanical Effects in Dry Sliding,” Wear 100 1984 453 476
- Newcomb T.P. Spurr R.T. “The Interaction between Friction Material and Lubricants,” Wear 24 1973 69 76
- Audebert N. Barber J.R. Zagrodzki P. “Buckling of Automatic Transmission Clutch Plates due to Thermoelastic/Plastic Residual Stress,” J. Thermal Stresses 21 1998 309 326