In designing of engine bearings for automobiles, we need to establish a mixed lubrication model that considers the solid-to-solid contact between journal surfaces and bearing surfaces with microgroove. However, as far as we know, there is no literature treating such problems. This paper describes theoretical modeling for microgrooved bearings under the mixed lubrication conditions with experimental verifications and prediction of performance in the actual engine bearings. In this modeling, a sectional shape of the microgrooved bearing was approximated to be a circular sectional shape. Contact pressure between the journal surfaces and the bearing surfaces with microgroove was calculated using the Hertzian contact model and the effects of elastic deformation of bearing surface due to hydrodynamic and contact pressures were considered. A numerical calculation model was developed to predict bearing performance under the mixed lubrication condition in microgrooved journal bearings. Oil film thickness distributions, hydrodynamic and contact pressure distributions, and real contact area between the journal surfaces and the bearing surfaces with microgroove were obtained simultaneously by the theoretical model. Moreover, friction coefficients under mixed lubrication conditions were determined by the theoretical model and the calculated results were compared with experimental results using test rig. The calculated results successfully agreed with the experimental results and the applicability of the model was verified. Moreover, the model was applied to predict the performance of engine bearings. In the numerical results, real contact area occurred relative widely under low-speed conditions when engine was started but friction loss was not excessive because of low shearing velocity. On the other hand, under high-speed engine conditions, the friction loss was large in spite of narrow real contact area because of high shearing velocity. Under both low-speed and high-speed conditions, the real contacts will occur severely at the edge of the bearing in the axial direction and at the bearing angles from 50 deg to 110 deg in circumferential direction. In addition, an appropriate design of the microgrooved bearing was examined under mixed lubrication conditions. In the design of the microgrooves, a cooling effect and an enough amount of oil flow to the contact area are needed. As the results from parametric studies using present theoretical model, an influence of the depth of the microgroove was the largest on the cooling effect and the enough amount of oil flow. In the case of typical operation condition, it was found that $1.0 μm$ of the groove depth was the most appropriate.

1.
,
Y.
,
Hashizume
,
Y.
, and
Kimura
,
Y.
, 1996, “
Performance of Plain Bearings With Circumferential Microgrooves
,”
Tribol. Trans.
1040-2004,
39
(
1
), pp.
81
86
.
2.
Patir
,
N.
, and
Cheng
,
H. S.
, 1978, “
An Average Flow Model for Determining Effects of Three-Dimensional Roughness on Partial Hydrodynamic Lubrication
,”
ASME J. Lubr. Technol.
0022-2305,
100
(
1
), pp.
12
16
.
3.
Christensen
,
H.
, and
Tonder
,
K.
, 1973, “
The Hydrodynamic Lubrication on Rough Journal Bearings
,”
ASME J. Lubr. Technol.
0022-2305,
95
, pp.
166
172
.
4.
Watanabe
,
K.
,
Hashizume
,
K.
,
Kimura
,
Y.
,
Ozasa
,
T.
,
Noda
,
T.
, and
Masuda
,
Y.
, 2000, “
A Study of Microgrooved Bearing Performance by Using Numerical Analysis
,” SAE Technical Paper No. 2000-01-1338.
5.
Oh
,
K. P.
, and
Goenka
,
P. K.
, 1985, “
,”
ASME J. Lubr. Technol.
0022-2305,
107
, pp.
389
395
.
6.
Dobrica
,
M. B.
,
Fillon
,
M.
, and
Maspeyrot
,
P.
, 2006, “
Mixed Elastohydrodynamic Lubrication in Partial Journal Bearings—Comparison Between Deterministic and Stochastic Models
,”
ASME J. Tribol.
0742-4787,
128
, pp.
778
788
.
7.
Zhu
,
D.
,
Cheng
,
H. S.
,
Arai
,
T.
, and
Hamai
,
K.
, 1992, “
A Numerical Analysis for Piston Skirt in Mixed Lubrication—Part I: Basic Modeling
,”
ASME J. Tribol.
0742-4787,
114
, pp.
553
562
.
8.
Wang
,
Q.
, and
Cheng
,
H. S.
, 1995, “
A Mixed Lubrication Model for Journal Bearings With a Soft Coating—Part I: Contact and Lubrication Analysis
,”
Tribol. Trans.
1040-2004,
38
, pp.
654
662
.
9.
Lundberg
,
G.
, 1939, “
Elastische Berührung zweier Halbräume
,”
Forsch. Geb. Ingenieurwes.
0367-2204,
10
(
5
), pp.
201
211
.
10.
Hertz
,
H.
, 1881, “
Über die Berührung fester elastischer Körper
,”
J. Reine Angew. Math.
0075-4102,
92
, pp.
156
171
.
11.
Fenner
,
D. N.
,
Mclvor
,
J. D. C.
,
Conway-Jones
,
J. M.
, and
Xu
,
H.
, 1993, “
The Effect of Compliance on Peak Oil Film Pressure in Connecting Rod Bearings
,”
Thin Films in Tribology
,
Elsevier Science Publishers B.V.
, pp.
149
156
.
12.
Zienkiewicz
,
O. C.
, 1977,
Finite Element Methods in Engineering Science
, 3rd ed.,
McGraw-Hill
,
New York
.
13.
Ozasa
,
T.
, 2006, “
Mass Conserving Elastohydrodynamic Lubrication Model of Engine Bearings Having Regular Striations
,”
Trans. Jpn. Soc. Mech. Eng., Ser. C
0387-5024,
72
(
721
), pp.
3030
3037
.