A hybrid evaluation scheme for EHL film thickness determination is proposed and discussed. The film thickness profile in the contact region is measured using interferograms produced with a novel multi channel interferometry method. Since the refractive index distribution in the contact is pressure-dependent, and the initial film thickness profile will be evaluated assuming atmospheric pressure, a refractive index correction scheme is employed. The correction scheme is based on the Lorenz-Lorentz equation and a pressure-density relation together with a numerical pressure solver taking the initial film thickness measurement as input. The film thickness determination scheme is applied to an interesting phenomenon that can be observed at sliding conditions when the discrepancy occurred in the form of a deep and large dimple in the conjunction. Such a dimple appeared instead of the conventional plateau. The phenomenon was studied under different degrees of sliding. The detailed film thickness maps and pressure distributions for highly loaded EHL conjunctions at high degrees of sliding are produced using a hybrid evaluation scheme. The results are analyzed and discussed. [S0742-4787(00)00301-5]

Issue Section:
Technical Papers
Keywords:
interferometry, thickness measurement, thin films, mechanical contact, lubrication, tribology
Topics:
Disks, Film thickness, Interferometry, Pressure, Refractive index, Lubricants
1.
Cameron, A., and Gohar, R., 1966, “Theoretical and experimental studies of the film in lubricated point contact,” Proc. of the Royal Society (London) Series A, pp. 520–536.
2.
Foord
,
C. A.
,
Hammann
,
W. C.
, and
Cameron
,
A.
,
1968
, “
Evaluation of lubricants using optical elastohydrodynamics
,”
ASLE Trans.
,
11
, pp.
31
–
43
.
3.
Wedeven
,
L. D.
,
Evans
,
D.
, and
Cameron
,
A.
,
1971
, “
Optical analysis of ball bearing starvation
,”
ASME J. Lubr. Technol.
,
93
, pp.
349
–
363
.
4.
Foord
,
C. A.
,
Wedeven
,
I. D.
,
Westlake
,
F. J.
, and
Cameron
,
A.
,
1969
–70, “
Optical elastohydrodynamics
,”
Proc. Inst. Mech. Eng.
,
184
, Pt 1, No.
28
, pp.
487
–
505
.
5.
Westlake
,
F. J.
, and
Cameron
,
A.
,
1967
–68, “
A study of ultra-thin lubricant films using an optical technique
,”
Proc. Inst. Mech. Eng.
,
182
, Part 3G, pp.
75
–
78
.
6.
Johnston
,
G. J.
,
Wayte
,
R.
, and
Spikes
,
H. A.
,
1991
, “
The measurement and study of very thin lubricant films in concentrated contacts
,”
Tribol. Trans.
,
34
, No.
2
, pp.
187
–
194
.
7.
Gustafsson
,
L.
,
Ho¨glund
,
E.
, and
Marklund
,
O.
,
1994
, “
Measuring lubricant film thickness with image analysis
,”
Proc. Instn. Mech. Engrs., Part J. J. of Eng. Tribology
,
208
, pp.
199
–
205
.
8.
Krupka, I., Hartl, M., Cermak, J., and Liska, M., 1998, “Elastohydrodynamic lubricant film shape—comparison between experimental and theoretical results,” Proc. 24th Leeds-Lyon Symposium on Tribology, pp. 221–232.
9.
Molimard, J., Querry, M., and Vergne, P., 1998, “New tools for the experimental study of EHD and limit lubrications,” presented at the 1998 Leeds-Lyon Symposium on Tribology, Lyon, France, Sept. 1998.
10.
Marklund, O., 1998, “A pseudo-phase stepping approach to interferometric measurements,” To be published. Also available as Research Report, TULEA 1998:09 Lulea˚ Univ. of Tech., S-97187 Lulea˚, Sweden.
11.
A˚stro¨m
,
H.
, and
Venner
,
C. H.
,
1994
, “
Soap thickener induced local pressure fluctuations in a grease lubricated EHD point contact
,”
Proc. Instn. Mech. Engrs., Part J, J. of Eng. Tribology
,
208
, pp.
191
–
208
.
12.
Jolkin, A., and Larsson, R., 1998, “Film thickness, pressure distribution and traction in sliding EHL conjunctions,” presented at the Sept. 1998 Leeds-Lyon Symposium on Tribology, Lyon, France.
13.
Marklund, O., and Gustafsson, L., 1999, “Correction for pressure dependence of refractive index in measurements of lubricant film thickness with image analysis,” to be published in Proc. Instn. Mech. Engrs., Part J, J. of Engineering Tribology.
14.
Kaneta
,
M.
,
Nishikawa
,
H.
,
Kanada
,
T.
, and
Matsuda
,
K.
,
1996
, “
Abnormal phenomena appearing in EHL contacts
,”
ASME J. Tribol.
,
118
, pp.
886
–
892
.
15.
Marklund
,
O.
,
1998b
, “
Noise-insensitive two-dimensional phase unwrapping method
,”
J. Opt. Soc. Am. A
,
15
, No.
1
, pp.
42
–
60
.
16.
Wong
,
P. L.
,
Lingard
,
S.
, and
Cameron
,
A.
,
1992
, “
The high pressure impact microviscometer
,”
Tribol. Trans.
,
35
, No.
3
, pp.
500
–
508
.
17.
Larsson
,
R.
, and
Lundberg
,
J.
,
1995
, “
Study of lubricated impact using optical interferometry
,”
Wear
,
190
, pp.
184
–
189
.
18.
Johnson, K. L. 1985, Contact Mechanics, Cambridge University Press.
19.
Brandt
,
A.
, and
Lubrecht
,
A. A.
,
1990
, “
Multilevel matrix multiplication and fast solution of integral equations
,”
J. Comput. Phys.
,
90
, No.
2
, pp.
348
–
370
.
20.
O¨stensen
,
J. O.
,
Larsson
,
R.
, and
Venner
,
C. H.
,
1996
, “
Determination of viscosity and pressure in an elastohydrodynamic rolling contact by using optical interferometry: a theoretical study
,”
Proc. Instn. Mech. Engrs., Part J, J. of Engineering Tribology
,
210
, pp.
259
–
268
.
21.
Ho¨glund, E., and Larsson, R., 1997, “Modelling non-steady ehl,” 23rd Leeds-Lyon Symposium, Elastohydrodynamics- ’96-Fundamentals and Applications in Lubrication and Traction, Tribology Series 32, Elsevier 1997.
22.
Ehret
,
P.
,
Dowson
,
D.
, and
Taylor
,
C. M.
,
1998
, “
On lubricant transport conditions in elastohydrodynamic conjunctions
,”
Proc. R. Soc. London, Ser. A
,
454
, pp.
763
–
787
.
Copyright © 2000
 by ASME
You do not currently have access to this content.