Wet clutches that handle the gearshifts in automatic transmission undergo severe thermal stresses due to the occurrence of large temperature gradients during engagement. To accurately design wet clutches, better models to simulate the engagement process are needed. This work presents a finite element model for simulating wet clutch engagements. The total friction coefficient was used to describe the different lubrication regimes that a wet clutch engagement undergoes. The model also includes provision for drive torque that realistically simulates the engine torque of a car. The results of the simulations are successfully verified by comparison with laboratory experiments on a testrig specially designed to accommodate the drive torque, covering a wide range of typical engagements. Excellent agreement between experiment and simulations is reported in terms of both the dynamics of the engagement and the thermal characteristics. The results are indicative of the utility of the model as a useful engineering tool.

1.
Evans
,
M.
, and
Whittle
,
J.
,
1967
, “
Friction in Wet Clutches
,”
Proc. Inst. Mech. Eng.
,
182
, Part 3N, pp.
132
138
.
2.
Fo¨rster
,
H. J.
,
1977
, “
Tribological Problems in Automatic Transmissions
,”
Proc. Inst. Mech. Eng.
,
C35/77
, pp.
43
54
.
3.
Holgerson, M., and Lundberg, J., 1999, “Engagement Behavior of a Paper-Based Wet Clutch: Part 1—Influence of Drive Torque,” Proc. Inst. Mech. Eng., Part D (J. Automob. Eng), 213, in press.
4.
Holgerson
,
M.
,
1997
, “
Apparatus for Measurement of Engagement Characteristics of a Wet Clutch
,”
Wear
,
213
, p.
140
140
.
5.
Kondo, T., Iwatsuki, K., Taga, Y., Tanguchi, T., and Taniguchi, T., 1990, “Toyota ‘ECT-i’ a New Automatic Transmission With Intelligent Electric Control System,” SAE Technical Paper 900550.
6.
Ibamoto, M., Kuroiwa, H., Minowa, T., Sato, K., and Tsuchiya, T., 1995, “Development of Smooth Shift Control System with Output Torque Estimation,” SAE Technical Paper 950900.
7.
El-Sherbiny
,
M.
, and
Newcomb
,
T. P.
,
1977
, “
Numerical Simulation of the Engagement Characteristics of a Wet Clutch
,”
Proc. Inst. Mech. Eng.
,
C63
, pp.
81
92
.
8.
Zagrodzki
,
P.
,
1985
, “
Numerical Analysis of Temperature Fields and Thermal Stresses in the Friction Discs of a Multidisc Wet Clutch
,”
Wear
,
101
, pp.
255
271
.
9.
Zagrodzki
,
P.
,
1990
, “
Analysis of Thermomechanical Phenomena in Multidisc Clutches and Brakes
,”
Wear
,
140
, pp.
291
308
.
10.
Zagrodzki
,
P.
,
1991
, “
Influence of Design and Material Factors on Thermal Stresses in Multiple Disc Wet Clutches and Brakes
,”
SAE Trans.
,
100n
, Sect. 2, pp.
395
405
.
11.
Natsumeda
,
S.
, and
Miyoshi
,
T.
,
1994
, “
Numerical Simulation of Engagement of Paper Based Wet Clutch Facing
,”
ASME J. Tribol.
,
116
, pp.
232
237
.
12.
Yang, Y., Lam, R. C., Chen, Y. F., and Yabe, H., 1995, “Modeling of Heat Transfer and Fluid Hydrodynamics for a Multidisc Wet Clutch,” SAE Technical Paper Series, No. 950898.
13.
Yang, Y., Lam, R. C., and Fujii, T., 1998, “Prediction of Torque Response During the Engagement of Wet Friction Clutch,” SAE Technical Paper Series, No. 981097.
14.
Berger
,
E. J.
,
Sadeghi
,
F.
, and
Krousgrill
,
C. M.
,
1996
, “
Finite Element Modeling of Engagement of Rough and Grooved Wet Clutches
,”
ASME J. Tribol.
,
118
, pp.
137
146
.
15.
Berger, E. J., Sadeghi, F., and Krousgrill, C. M., 1996, “Analytic and Numerical Modeling of Engagement of Rough, Permeable, Grooved Wet Clutches,” STLE Preprint No. 96-TRIB-3.
16.
Jang
,
J. Y.
, and
Khonsari
,
M. M.
,
1999
, “
Thermal Characteristics of a Wet Clutch
,”
ASME J. Tribol.
,
121
, pp.
610
618
.
17.
Haviland, M. L., Rodgers, J. J., and Davison, E. D., 1963, “Surface Temperatures and Friction in Lubricated Clutches,” SAE Technical Paper 642B.
18.
Anderson, A. E., 1972, “Friction and Wear of Paper Type Wet Friction Elements,” SAE Technical Paper 720521.
19.
Ohkawa, S., Kuse, T., Kawasaki, N., Shibata, A., and Yamashita, M., 1991, “Elasticity—An Important Factor of Wet Friction Materials,” SAE Technical Paper 911775.
20.
Yoshizawa, K., Akashi, T., and Yoshioka, T., 1990, “Proposal of New Criteria and Test Methods for the Dynamic Performance of ATF,” SAE Technical Paper 900810.
21.
Miyoshi
,
T.
,
1991
, “
Friction Characteristics of Paper Based Friction Materials
,”
Jpn. J. Tribol.
,
36
, p.
1385
1385
.
22.
Osanai, H., Ikeda, K., and Kato, K., 1990, “Relations Between Temperature in Friction Surface and Degradation of Friction Materials During Engaging of Wet Friction Paper,” SAE Technical Paper 900553, p. 1.
23.
Sanda, S., Nagasawa, Y., Suzuki, A., Hayashi, K., and Itoh, H., 1996, “Mechanism of Friction of Wet Clutch With Paper Based Facings Part 1: Observation and Modeling of Facing Surface During Engagement,” Proceedings of the International Tribology Conference, Yokohama 29 October–2 January 1995, p. 1519.
24.
Anleitner, M. A., 1994, “Reconciling Empirical and Theoretical Views of Lubrication in Wet Clutch Devices,” SAE Technical Paper 941102.
25.
Xin
,
R. C.
, and
Tao
,
W. K.
,
1994
, “
Analytical Solution for Transient Heat Conduction in Two Semi-Infinite Bodies in Contact
,”
ASME J. Heat Transfer
,
116
, pp.
224
227
.
26.
Incropera, F. P., and DeWitt, D. P., 1996, Introduction to Heat Transfer, Wiley, New York, ISBN 0-471-30458-1.
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