One of the main interests of gas foil bearings lies in their superior rotordynamic characteristics compared with conventional bearings. A numerical investigation on the stability limit and on the unbalanced response of foil bearings is presented in this paper. The main difficulty in modeling the dynamic behavior of such bearings comes from the dry friction that occurs within the foil structure. Indeed, dry friction is highly nonlinear and is strongly influenced by the dynamic amplitude of the pressure field. To deal with these nonlinearities, a structural dynamic model has been developed in a previous work. This model considers the entire corrugated foil and the interactions between the bumps by describing the foil bearing structure as a multiple degrees of freedom system. It allows the determination of the dynamic friction forces at the top and at the bottom of the bumps by simple integration of ordinary differential equations. The dynamic displacements of the entire corrugated sheet are then easily obtained at each time step. The coupling between this structural model and a gas bearing prediction code is presented in this paper and allows performing full nonlinear analyses of a complete foil bearing. The bearing stability is the first investigated problem. The results show that the structural deflection enhances the stability of compliant surface bearings compared with rigid ones. Moreover, when friction is introduced, a new level of stability is reached, revealing the importance of this dissipation mechanism. The second investigated problem is the unbalanced response of foil bearings. The shaft trajectories depict a nonlinear jump in the response of both rigid and foil bearings when the value of the unbalance increases. Again, it is evidenced that the foil bearing can support higher mass unbalance before this undesirable step occurs.

1.
Chen
,
M. H.
,
Howarth
,
R.
,
Geren
,
B.
,
Theylacker
,
J. C.
, and
Soyars
,
W. M.
, 2001, “
Application of Foil Bearings to Helium Turbocompressor
,”
Proceedings of the 30th Turbomachinery Symposium
, Texas A&M University,
Houston, TX
, September 17–20.
2.
Braun
,
M. J.
,
Choy
,
F. K.
,
Dzodzo
,
M.
, and
Hsu
,
J.
, 1996, “
Steady-State and Transient Dynamic Simulation of a Continuous Foil Bearing
,”
STLE Tribol. Trans.
1040-2004,
39
(
2
), pp.
322
329
.
3.
Heshmat
,
H.
,
Walowit
,
J. A.
, and
Pinkus
,
O.
, 1983, “
Analysis of Gas-Lubricated Foil Journal Bearings
,”
ASME J. Lubr. Technol.
0022-2305,
105
, pp.
647
655
.
4.
Heshmat
,
H.
,
Walowit
,
J. A.
, and
Pinkus
,
O.
, 1983, “
Analysis of Gas-Lubricated Compliant Thrust Bearings
,”
ASME J. Lubr. Technol.
0022-2305,
105
, pp.
638
646
.
5.
Walowit
,
J. A.
, and
Anno
,
J. N.
, 1975,
Modern Developments in Lubrication Mechanics
,
Applied Science
,
London, UK
, Chap. 7.
6.
Peng
,
Z. C.
, and
Khonsari
,
M. M.
, 2004, “
Hydrodynamic Analysis of Compliant Foil Air Bearings With Compressible Air Flow
,”
ASME J. Tribol.
0742-4787,
126
, pp.
542
546
.
7.
Peng
,
Z. C.
, and
Khonsari
,
M. M.
, 2004, “
On the Limiting Load-Carrying Capacity of Foil Bearings
,”
ASME J. Tribol.
0742-4787,
126
, pp.
817
818
.
8.
Iordanoff
,
I.
, 1999, “
Analysis of an Aerodynamic Compliant Foil Thrust Bearing: Method for a Rapid Design
,”
ASME J. Tribol.
0742-4787,
121
, pp.
816
822
.
9.
San Andres
,
L.
, 1995, “
Turbulent Flow Foil Bearings for Cryogenic Applications
,”
ASME J. Tribol.
0742-4787,
117
, pp.
185
195
.
10.
Kim
,
T. H.
, and
San Andres
,
L.
, 2005, “
Heavily Loaded Gas Foil Bearings: A Model Anchored to Test Data
,” ASME Paper No. GT 2005-68486.
11.
Kim
,
T. H.
, and
San Andres
,
L.
, 2005, “
Analysis of Gas Foil Bearings With Piecewise Linear Elastic Supports
,” ASME Paper No. WTC 2005-63397.
12.
Ku
,
C. P.
, and
Heshmat
,
H.
, 1992, “
Compliant Foil Bearing Structural Stiffness Analysis—Part I: Theoretical Model Including Strip and Variable Bump Foil Geometry
,”
ASME J. Tribol.
0742-4787,
114
, pp.
394
400
.
13.
Carpino
,
M.
, and
Talmage
,
G.
, 2003, “
A Fully Coupled Finite Element Formulation for Elastically Supported Foil Journal Bearings
,”
STLE Tribol. Trans.
1040-2004,
46
(
4
), pp.
560
565
.
14.
Carpino
,
M.
, and
Talmage
,
G.
, 2006, “
Prediction of Rotor Dynamic Coefficients in Gas Lubricated Foil Journal Bearings With Corrugated Sub-Foils
,”
STLE Tribol. Trans.
1040-2004,
49
, pp.
400
409
.
15.
Carpino
,
M.
, and
Talmage
,
G.
, 2007, “
Sub-Foil Stiffness Effects in Gas Lubricated Foil Journal Bearings
,”
Proceedings of the STLE Conference
, Philadelphia, May 6–10.
16.
Le Lez
,
S.
,
Arghir
,
M.
, and
Frene
,
J.
, 2007, “
Static and Dynamic Characterization of a Bump-Type Foil Bearing Structure
,”
ASME J. Tribol.
0742-4787,
129
, pp.
75
83
.
17.
Le Lez
,
S.
,
Arghir
,
M.
, and
Frene
,
J.
, 2007, “
A New Bump-Type Foil Bearing Structure Analytical Model
,”
ASME J. Eng. Gas Turbines Power
0742-4795,
129
(
4
), pp.
1047
1057
.
18.
Le Lez
,
S.
,
Arghir
,
M.
, and
Frene
,
J.
, 2007, “
A New Foil Bearing Dynamic Structural Model
,”
Proceedings of the STLE/ASME International Joint Tribology Conference
, ASME Paper No. IJTC2007-44110.
19.
Petrov
,
E. P.
, and
Ewins
,
D. J.
, 2004, “
Generic Friction Models for Time-Domain Vibration Analysis of Bladed Disks
,”
ASME J. Turbomach.
0889-504X,
126
, pp.
184
192
.
20.
Arghir
,
M.
,
Le Lez
,
S.
, and
Frene
,
J.
, 2006, “
The Finite Volume Solution of the Compressible Reynolds Equation—Linear and Non Linear Analysis of Gas Bearings
,”
Proc. Inst. Mech. Eng., Part J: J. Eng. Tribol.
1350-6501,
220
, pp.
617
627
.
21.
Ruscitto
,
D.
,
Mc Cormick
,
J.
, and
Gray
,
S.
, 1978, “
Hydrodynamic Air Lubricated Compliant Surface Bearing for an Automotive Gas Turbine Engine I-Journal Bearing Performance
,”
NASA
, Technical Report No. CR-135368.
22.
Adams
,
M. L.
, 2001,
Rotating Machinery Vibration
,
Dekker
,
New York
.
23.
Carpino
,
M.
, and
Talmage
,
G.
, 2006, “
Prediction of Rotor Dynamic Coefficients in Gas Lubricated Foil Journal Bearings With Corrugated Sub-Foils
,”
STLE Tribol. Trans.
1040-2004,
49
, pp.
400
409
.
24.
Le Lez
,
S.
,
Arghir
,
M.
, and
Frêne
,
J.
, 2008, “
Non Linear Dynamic Analysis of Foil Bearings
,”
Proceedings of the ISROMAC Conference
,
Honolulu, HI
, February 17–22, Paper No. ISROMAC12-2008-20082.
You do not currently have access to this content.