By means of numerical simulations the effects of the loading system on the contact dynamics of an EHL contact during start up have been studied. The work was initiated by experimental results obtained for the start up situation on a ball on disk apparatus in which strong film thickness oscillations were observed. In this paper it is shown how much, under operational conditions as they appear in a ball on disc rig, inertia, and stiffness related to the configuration of the loading system can influence the film thickness and mutual approach. For this purpose a model was used in which the usual force balance equation has been replaced by an equation of motion for the loading system in which an inertia and spring effect appear. It was shown that for large accelerations, the loading system does induce oscillations in the film thickness, and predictive formulas for the oscillation frequency derived from a dry contact analysis are shown to be accurate. The nature of the oscillations is explained in relation to the general aspects of time dependent solutions to EHL problems. However, the predicted oscillation amplitudes are small compared to what is seen in the experiments and although some of the phenomena shown in the solutions presented here also appear in the experimental results the experimentally observed oscillatory behavior appears to be of a different nature. As the model used here has given good predictions of the dynamic behavior of single contacts in ball on disc experiments in earlier studies it is concluded that it is unlikely that the oscillatory behavior observed in the experiments is only due to the dynamics of the loading system and other effects must play a role.

Issue Section:
Technical Papers
Keywords:
lubrication, hydrodynamics, point contacts, fluid oscillations, elastic constants
Topics:
Film thickness, Inertia (Mechanics), Oscillations, Stress, Springs
1.
Foord
,
C. A.
,
Wedeven
,
L. D.
,
Westlake
,
F. J.
, and
Cameron
,
A.
,
1969
, “
Optical Elastohydrodynamics
,”
Proc. Inst. Mech. Eng.
,
148
, pp.
487
–
505
.
2.
Kaneta
,
M.
,
Sakai
,
T.
, and
Nishikawa
,
H.
,
1992
, “
Optical Interferometric Observations of the Bump on Point Contact EHL
,”
ASME J. Tribol.
,
114
, pp.
779
–
784
.
3.
Johnston
,
G. J.
,
Wayne
,
R. C.
, and
Spikes
,
H. A.
,
1991
, “
The Measurement of Very Thin Lubricant Films in Concentrated Contacts
,”
ASLE Trans.
,
34
, pp.
187
–
194
.
4.
Cann
,
P. M.
,
Spikes
,
H. A.
, and
Hutchinson
,
J.
,
1996
, “
The Development of a Spacer Layer Imaging Method for Mapping Elastohydrodynamic Contacts
,”
STLE Tribol. Trans.
,
36
(
4
), pp.
915
–
921
.
5.
Sugimura, J., and Spikes, H. A., 1997, “Technique for Measuring EHD Film Thickness in Non-Steady State Contact Conditions,” Proc. 23rd Leeds-Lyon Symposium, D. Dowson et al., ed., Elsevier Tribology Series, 32, pp. 91–100.
6.
Choo
,
J. W.
,
Olver
,
A. V.
,
Glovnea
,
R. P.
, and
Spikes
,
H. A.
,
2002
, “
The effects of 3D Model Surface Roughness Features on Lubricant Film Thickness in EHL Contacts
,”
ASME J. Tribol.
,
125
(
3
), pp.
533
–
542
.
7.
Lubrecht, A., 1987, “The Numerical Solution of the Elastohydrodynamically Lubricated Line and Point Contact Problem Using Multigrid Techniques,” PhD. thesis, University of Twente, Enschede, ISBN 90-9001583-3.
8.
Venner, C. H., 1991, “Multilevel Solution of Solution of the EHL Line and Point Contact Problems,” PhD. thesis, University of Twente, Enschede, The Netherlands. ISBN 90-9003974-0
9.
Venner, C. H., and Lubrecht, A. A., 2000, “Multilevel Methods in Lubrication,” Tribology Series, D. Dowson, ed., 37, Elsever, Amsterdam.
10.
Venner
,
C. H.
, and
Lubrecht
,
A. A.
,
1994a
, “
Numerical Simulation of a Transverse Ridge in a Circular EHL Contact, Under Rolling/Sliding
,”
ASME J. Tribol.
,
116
, pp.
751
–
761
.
11.
Venner, C. H., and Lubrecht, A. A., 1994, “Numerical Simulation of Waviness in a Circular EHL Contact, Under Rolling/Sliding,” Proc. 20th Leeds-Lyon Symposium on Tribology, D. Dowson et al., ed., Elsevier Tribology Series, 30, pp. 259–272.
12.
Morales Espejel, G. E., 1993, “Elastohydrodynamic Lubrication of Smooth and Rough Surfaces,” PhD. thesis, University of Cambridge, Department of Engineering.
13.
Greenwood
,
J. A.
, and
Morales Espejel
,
G. E.
,
1994
, “
The Behavior of Transverse Roughness in EHL Contacts
,”
Proc. Inst. Mech. Eng.
,
208
, pp.
121
–
132
.
14.
Venner, C. H., Couhier, F., Lubrecht, A. A., and Greenwood, J., 1997 “Amplitude Reduction of Waviness in Transient EHL Line Contacts,” Proc. 23rd Leeds-Lyon Tribology Conference, D. Dowson et al., ed., Elsevier Tribology Series, 32, pp. 103–112.
15.
Hooke
,
C. J.
,
1997
, “
Surface Roughness Modification in Elastohydrodynamic Line Contacts Operating in the elastic Piezoviscous Regime
,”
Proc. Inst. Mech. Eng., Part J: J. Eng. Tribol.
,
212
, pp.
145
–
162
.
16.
Masen
,
M. A.
,
Venner
,
C. H.
,
Lugt
,
P. M.
, and
Trip
,
J. H.
,
2002
, “
Effects of Surface Micro-Geometry on the Lift-Off Speed of an EHL Contact
,”
STLE Tribol. Trans.
,
45
(
1
), pp.
21
–
30
.
17.
Glovnea
,
R. P.
, and
Spikes
,
H. A.
,
2000
, “
The Influence of Lubricant on Film Collapse Rate in High Pressure Thin Film Behavior During Sudden Halting of Motion
,”
STLE Tribol. Trans.
,
43
(
4
), pp.
731
–
739
.
18.
Glovnea
,
R. P.
, and
Spikes
,
H. A.
,
2001
, “
Elastohydrodynamic Film Formation at the Start up of the Motion
,”
Proc. Inst. Mech. Eng., Part J: J. Eng. Tribol.
,
215
, pp.
125
–
138
.
19.
Glovnea
,
R. P.
, and
Spikes
,
H. A.
,
2001
, “
Elastohydrodynamic Film Collapse During Rapid Decelaration—Part I: Experimental Results
,”
ASME J. Tribol.
,
123
, pp.
254
–
261
.
20.
Glovnea
,
R. P.
, and
Spikes
,
H. A.
,
2001
, “
Elastohydrodynamic Film Collapse During Rapid Deceleration—Part II: Theoretical Analysis and Comparison of Theory to Experiment
,”
ASME J. Tribol.
,
123
, pp.
262
–
267
.
21.
Zhao
,
J.
,
Sadeghi
,
F.
, and
Hoeprich
,
M. H.
,
2001
, “
Analysis of EHL Circular Contact Start Up: Part I—Mixed Contact Model With Pressure and Film Thickness Results
,”
ASME J. Tribol.
,
123
, pp.
67
–
74
.
22.
Zhao
,
J.
,
Sadeghi
,
F.
, and
Hoeprich
,
M. H.
,
2001
, “
Analysis of EHL Circular Contact Start Up: Part II Thermal Model with Surface Results
,”
ASME J. Tribol.
,
123
, pp.
75
–
82
.
23.
Zhao
,
J.
, and
Sadeghi
,
F.
,
2003
, “
Analysis of EHL Circular Contact Shut Down
,”
ASME J. Tribol.
,
125
, pp.
76
–
90
.
24.
Holmes, M. J. A., Evans, H. P., and Snidle, R. W., 2002, “Comparison of Transient EHL Calculations With a Start Up Experiment,” Proc. 29th Leeds-Lyon Symposium on Tribology, Elseviers Tribology Series, D. Dowson et al., eds., 41, pp. 79–89.
25.
Holmes, M. J. A., Evans, H. P., and Snidle, R. W., 2002, “Comparison of Transient EHL Calculations With a Shut-Down Experiment,” Proc. 29th Leeds-Lyon Symposium on Tribology, Elseviers Tribology Series, D. Dowson et al., eds., 41, pp. 91–99.
26.
Wynant, Y. H., and Venner, C. H. 1997, “Analysis of an EHL Circular Contact Incorporating Rolling Element Vibration,” Proc. 23rd Leeds-Lyon Symposium on Tribology, D. Dowson et al., ed., Elseviers Tribology Series, 32, pp. 445–456.
27.
Wynant, Y. H., 1998, “Contact Dynamics in the field of Elastohydrodynamic Lubrication,” PhD. thesis, University of Twente, Enschede, The Netherlands, ISBN 90-36512239.
28.
Wijnant
,
Y. H.
,
Venner
,
C. H.
, and
Larsson
,
R.
, and
Eriksson
,
P.
,
1999
, “
Effects of Structural Vibrations on the Film Thickness in an EHL Circular Contact
,”
ASME J. Tribol.
,
121
,
259
–
264
.
29.
Wensing, J. A., 1998, “On the Dynamics of Ball Bearings,” PhD. thesis, University of Twente, Enschede, The Netherlands, ISBN 90-36512298.
30.
Dowson, D., and Higginson, G. R., 1966, Elasto-Hydrodynamic Lubrication, The Fundamentals of Roller and Gear Lubrication, Pergamon Press, Oxford, Great Britain.
31.
Roelands, C. J. A., 1966, “Correlational Aspects of the Viscosity-Temperature-Pressure Relationship of Lubricating Oils,” Ph.D. thesis, Technical University Delft, Delft, The Netherlands, (V.R.B., Groningen, The Netherlands).
32.
Venner
,
C. H.
, and
Morales Espejel
,
G. E.
,
1999
, “
Amplitude Reduction of Small Amplitude Waviness in Transient EHL Line Contacts
,”
Proc. Inst. Mech. Eng., Part J: J. Eng. Tribol.
,
213
, pp.
487
–
504
.
33.
Newmark
,
N. M.
,
1959
, “
A Method of Computation for Structural Dynamics
,”
J. Eng. Mech. Div.
,
85
, pp.
76
–
94
.
Copyright © 2004
 by ASME
You do not currently have access to this content.