In ElastoHydrodynamic Lubrication (EHL), transient processes are much more common than stationary ones. Predicting the film thickness under steady state conditions has become straight forward. Using numerical methods, the effect of transient conditions on the film thickness profile can be computed. However, those analyses are very time consuming even using advanced numerical techniques. As such, they are inadequate for industrial applications as design and development. This paper shows that under certain assumptions, an approximate formula of the transient film thickness profile can be derived under transient operating conditions. The variations can occur in the geometry, the load or the hydrodynamic velocity. The theory can handle all variations separately, or even a combination of several parameters varying simultaneously. The analytical approximation obtained is rather good apart from the constriction at the contact edge(s). This approach can be applied to any set of time dependent conditions (load, speed, geometry). As an example an EHL contact is studied in which reversal of the entrainment velocity occurs.

Issue Section:
Technical Papers
Keywords:
hydrodynamics, elasticity, lubrication, film flow, tribology
Topics:
Film thickness, Transients (Dynamics)
1.
Dowson, D., and Higginson, G. R., 1966, Elasto-Hydrodynamic Lubrication, SI, Oxford, Pergamon Press Ltd, p. 236.
2.
Hamrock
,
B. J.
, and
Dowson
,
D.
,
1976
, “
Isothermal EHD Lubrication of Points Contacts: Part I—Theoretical Formulation
,”
ASME J. Lubr. Technol.
,
98
, No.
2
, pp.
223
–
229
.
3.
Hooke
,
C. J.
,
1992
, “
The Minimum Film Thickness in Lubricated Line Contacts During a Reversal of Entrainment Isoviscous Behavior
,”
Proceeding of the ImechE
,
206
, Part J, pp.
337
–
345
.
4.
Hooke
,
C. J.
,
1993
, “
The Minimum Film Thickness in Line Contacts during a Reversal of Entrainment
,”
ASME J. Tribol.
,
115
, pp.
191
–
199
.
5.
Sugimura
,
J.
,
Okumura
,
T.
,
Yamamoto
,
Y.
, and
Spikes
,
H. A.
,
1999
, “
Simple Equation for Elastohydrodynamic Film Thickness Under Acceleration
,”
Transaction of Tribology International
,
32
, pp.
117
–
123
.
6.
Kaneta, M., 1999, “For the Establishment of a New EHL Theory,” Proceeding of the Leeds-Lyon Symposium on Tribology, Lubrication at the Frontier, 36, pp. 25–36.
7.
Glovnea, R. P., and Spikes, H. A., 2001, “The Influence of Cam-Follower Motion on Elastohydrodynamic Film Thickness,” Proceeding of the Leeds-Lyon Symposium on Tribology 2001, Vol. 39, pp. 485–493.
8.
Dowson
,
D.
,
Taylor
,
C. M.
, and
Zhu
,
G.
,
1992
, “
A Transient Elastohydrodynamic Lubrication Analysis of a Cam and Follower
,”
J. Appl. Phys.
,
25
, pp.
313
–
320
.
9.
Ai
,
X.
, and
Haiqing
,
Y.
,
1989
, “
A Numerical Analysis for the Transient EHL Process of a Cam-Tappet Pair in I.C. Engine
,”
ASME J. Tribol.
,
111
, pp.
413
–
417
.
10.
Glovnea
,
R. P.
, and
Spikes
,
H. A.
,
2000
, “
Elastohydrodynamic Film Collapse During Rapid Deceleration. Part I: Experimental Results
,”
ASME J. Tribol.
,
123
, No.
2
, pp.
254
–
261
.
11.
Glovnea
,
R. P.
, and
Spikes
,
H. A.
,
2000
, “
Elastohydrodynamic Film Collapse During Rapid Deceleration. Part II: Theoretical Analysis and Comparison of Theory and Experiment
,”
ASME J. Tribol.
,
123
, No.
2
, pp.
262
–
267
.
12.
Messe´, S., and Lubrecht, A. A., 2000, “Transient Elastohydrodynamic Analysis of an OHC cam/Tappet Contact,” Proceeding of the IMechE: Journal of Engineering Tribology, 214, pp. 415–425.
13.
Venner
,
C. H.
, and
Lubrecht
,
A. A.
,
2000
, “
Multilevel Methods in Lubrication
,”
Tribol. Ser.
,
37
,
Elsevier
Elsevier
.
14.
Messe´, S., 2001, “Analyse Transitoire de la Lubrification et du Frottement dans un Syste`me de Distribution Automobile,” Ph.D. thesis, INSA de Lyon, France.
Copyright © 2002
 by ASME
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