This theoretical study concentrates on the mathematical analysis of the motion of small (5–50 μm) spherical solid particles in the inlet zone of elastohydrodynamic point contacts, found in various machine elements as, for example, in ball bearings, in order to compute the particle trajectories in the fluid flow. Particles may collide on a moving element of the contact (e.g., a ball in a bearing) or bypass it. For those particles that collide on another element, a fluid and mechanical force analysis reveals if they will be entrapped and, possibly, cause surface damage, or temporarily or finally expelled. Particle rejection is associated with the risk of inlet blockage and fluid starvation, which may further cause film collapse and scuffing. The study gives useful evidence of the probabilities of particle entrapment or rejection, extending the concept to evaluate the probabilities of oil starvation, surface indentation, or both, under various operating conditions.

Issue Section:
Technical Papers
Keywords:
hydrodynamics, elasticity, mechanical contact, lubrication, indentation, surface topography, tribology
Topics:
Particulate matter, Probability
1.
Stokes
,
G. G.
,
1850
, “
On the Effect of the Internal Friction of Fluids on the Motion of Pendulums
,”
Proc. Cambridge Philos. Soc.
,
1
, pp.
104
–
106
.
2.
Jeffery
,
G. B.
,
1922
, “
The Motion of Ellipsoidal Particles Immersed in a Viscous Fluid
,”
Proc. R. Soc. London, Ser. A
,
102
, pp.
161
–
179
.
3.
Rubinow
,
S. I.
, and
Keller
,
J. B.
,
1961
, “
The Transverse Force on a Spinning Sphere Moving in a Viscous Fluid
,”
J. Fluid Mech.
,
11
, pp.
447
–
459
.
4.
Bretherton
,
F. P.
,
1962
, “
The Motion of Rigid Particles in a Shear Flow at Low Reynolds Number
,”
J. Fluid Mech.
,
14
, pp.
284
–
304
.
5.
Saffman
,
P. G.
,
1965
, “
The Lift on a Small Sphere in a Slow Shear Flow
,”
J. Fluid Mech.
,
22
, pp.
385
–
400
.
6.
Leal
,
L. G.
,
1979
, “
The Motion of Small Particles in Non-Newtonian Fluids
,”
J. Non-Newtonian Fluid Mech.
,
5
, pp.
33
–
78
.
7.
Leal
,
L. G.
,
1980
, “
Particle Motions in a Viscous Fluid
,”
Annu. Rev. Fluid Mech.
,
12
, pp.
435
–
476
.
8.
Brunn
,
P.
,
1976
, “
The Slow Motion of a Sphere in a Second-Order Fluid
,”
Rheol. Acta
,
15
(
3/4
), pp.
163
–
171
.
9.
Brunn
,
P.
,
1976
, “
The Behavior of a Sphere in Non-Homogeneous Flows of a Viscoelastic Fluid
,”
Rheol. Acta
,
15
(
11/12
), pp.
589
–
611
.
10.
Brunn
,
P.
,
1977
, “
Interaction of Spheres in a Viscoelastic Fluid
,”
Rheol. Acta
,
16
(
5
), pp.
461
–
475
.
11.
Drew
,
D. A.
,
1978
, “
The Force on a Small Sphere in Slow Viscous Flow
,”
J. Fluid Mech.
,
88
, pp.
393
–
400
.
12.
Sugihara-Seki
,
M.
,
1993
, “
The Motion of an Elliptical Cylinder in Channel Flow at Low Reynolds Numbers
,”
J. Fluid Mech.
,
257
, pp.
575
–
596
.
13.
Saville
,
D. A.
,
1977
, “
Electrokinetic Effects With Small Particles
,”
Annu. Rev. Fluid Mech.
,
9
, pp.
321
–
337
.
14.
Sayles
,
R. S.
, and
Ioannides
,
E.
,
1988
, “
Debris Damage in Rolling Bearings and Its Effects on Fatigue Life
,”
ASME J. Tribol.
,
110
, pp.
26
–
31
.
15.
Nikas
,
G. K.
,
2001
, “
Mathematical Analysis of the Entrapment of Solid Spherical Particles in Non-Conformal Contacts
,”
ASME J. Tribol.
,
123
(
1
), pp.
83
–
93
.
16.
Dai
,
F.
, and
Khonsari
,
M. M.
,
1993
, “
A Continuum Theory of a Lubrication Problem With Solid Particles
,”
ASME J. Appl. Mech.
,
60
, pp.
48
–
58
.
17.
Dwyer-Joyce, R. S., and Heymer, J., 1996, “The Entrainment of Solid Particles into Rolling Elastohydrodynamic Contacts,” Proc. of the 22nd Leeds-Lyon Symposium on Tribology, Tribology Series, 31, Elsevier, pp. 135–140.
18.
Kumar
,
A.
,
Schmid
,
S. R.
, and
Wilson
,
W. R. D.
,
1997
, “
Particle Behavior in Two-Phased Lubrication
,”
Wear
,
206
, pp.
130
–
135
.
19.
Nikas, G. K., Sayles, R. S., and Ioannides, E., 1998, “Effects of Debris Particles in Sliding/Rolling Elastohydrodynamic Contacts,” Proc. IMechE, Part J: J. Engineering Tribology, (ISSN 1350–6501), 212, No. J5, pp. 333–343.
20.
Nikas, G. K., 1999, “Theoretical Modelling of the Entrainment and Thermomechanical Effects of Contamination Particles in Elastohydrodynamic Contacts,” Ph.D. thesis, Imperial College, Mech. Eng. Dept., Tribology Section, London, England.
21.
Wan
,
G. T. Y.
, and
Spikes
,
H. A.
,
1988
, “
The Behavior of Suspended Solid Particles in Rolling and Sliding Elastohydrodynamic Contacts
,”
STLE Tribol. Trans.
,
31
(
1
), pp.
12
–
21
.
22.
Cusano
,
C.
, and
Sliney
,
H. E.
,
1982
, “
Dynamics of Solid Dispersions in Oil During the Lubrication of Point Contacts, Part I—Graphite
”
ASLE Trans.
,
25
(
2
), pp.
183
–
189
.
23.
Nikas
,
G. K.
,
Ioannides
,
E.
, and
Sayles
,
R. S.
,
1999
, “
Thermal Modeling and Effects From Debris Particles in Sliding/Rolling EHD Line Contacts—A Possible Local Scuffing Mode
,”
ASME J. Tribol.
,
121
(
2
), pp.
272
–
281
.
24.
Nikas
,
G. K.
,
2001
, “
An Advanced Model to Study the Possible Thermomechanical Damage of Lubricated Sliding-Rolling Line Contacts From Soft Particles
,”
ASME J. Tribol.
,
123
(
4
), pp.
828
–
841
.
Copyright © 2002
 by ASME
You do not currently have access to this content.