Mixed Elastohydrodynamic Lubrication in a Partial Journal Bearing—Comparison Between Deterministic and Stochastic Models

The analysis of the mixed lubrication phenomena in journal and axial bearings represents nowadays the next step towards a better understanding of these devices, subjected to more and more severe operating conditions. While the theoretical bases required for an in-depth analysis of the mixed-lubrication regime have long been established, only small-scale numerical modeling was possible due to computing power limitations. This led to the appearance of averaging models, thus making it possible to generalize the trends observed in very small contacts, and to include them in large-scale numerical analyses. Unfortunately, a lack of experimental or numerical validations of these averaging models is observed, so that their reliability remains to be demonstrated. This paper proposes a deterministic numerical solution for the hydrodynamic component of the mixed-lubrication problem. The model is applicable to small partial journal bearings, having a few centimeters in width and diameter. Reynolds' equation is solved on a very thin mesh, and pad deformation due to hydrodynamic pressure is taken into account. Deformation due to contact pressure is neglected, which limits the applicability of the model in those cases where extended contact is present. The results obtained with this deterministic model are compared to the stochastic solution proposed by Patir and Cheng, in both hydrodynamic and elastohydrodynamic regimes. The rough surfaces used in this study are numerically generated (Gaussian) and are either isotropic or oriented, having different correlation lengths. It is shown that the stochastic model of Patir and Cheng correctly anticipates the influence of roughness over the pressure field, for different types of roughness. However, when compared to the smooth surface solution, the correction introduced by this model only partially compensates for the differences observed with a deterministic analysis.

[1]  Chih Lin,et al.  A mixed-TEHD analysis and experiment of journal bearings under severe operating conditions , 2002 .

[2]  H. Cheng,et al.  Application of Average Flow Model to Lubrication Between Rough Sliding Surfaces , 1979 .

[3]  Herbert S. Cheng,et al.  Effect of Surface Topography on Contact Fatigue in Mixed Lubrication , 2003 .

[4]  Dong Zhu,et al.  Mixed Lubrication Analyses by a Macro-Micro Approach and a Full-Scale Mixed EHL Model , 2004 .

[5]  Ning Ren,et al.  Contact Simulation of Three-Dimensional Rough Surfaces Using Moving Grid Method , 1993 .

[6]  N. S. Rao,et al.  Thermohydrodynamic Analysis of Submerged Oil Journal Bearings Considering Surface Roughness Effects , 1997 .

[7]  Richard F. Salant,et al.  Inter-asperity cavitation and global cavitation in seals:: an average flow analysis , 2002 .

[8]  William R. D. Wilson,et al.  Partial Hydrodynamic Lubrication With Large Fractional Contact Areas , 1998 .

[9]  Dong Zhu,et al.  Effects of Rough Surface Topography and Orientation on the Characteristics of EHD and Mixed Lubrication in Both Circular and Elliptical Contacts , 2001 .

[10]  Hui Wang,et al.  A computer model of mixed lubrication in point contacts , 2001 .

[11]  Henry Peredur Evans,et al.  Simulation of Elastohydrodynamic Contacts Between Rough Surfaces , 1992 .

[12]  Yuan-zhong Hu,et al.  Effect of surface roughness parameters on mixed lubrication characteristics , 2006 .

[13]  Chengwei Wu,et al.  An Average Reynolds Equation for Partial Film Lubrication With a Contact Factor , 1989 .

[14]  Nadir Patir,et al.  A numerical procedure for random generation of rough surfaces , 1978 .

[15]  Qian Wang,et al.  A Mixed-TEHD Model for Journal-Bearing Conformal Contact—Part II: Contact, Film Thickness, and Performance Analyses , 1997 .

[16]  H. Cheng,et al.  An Average Flow Model for Determining Effects of Three-Dimensional Roughness on Partial Hydrodynamic Lubrication , 1978 .

[17]  Henry Peredur Evans,et al.  Micro-Elastohydrodynamic Lubrication of an Elliptical Contact With Transverse and Three-Dimensional Sinusoidal Roughness , 1989 .

[18]  Qian Wang,et al.  A Mixed-TEHD Model for Journal-Bearing Conformal Contacts—Part I: Model Formulation and Approximation of Heat Transfer Considering Asperity Contact , 1997 .

[19]  Richard F. Salant,et al.  An Average Flow Model of Rough Surface Lubrication With Inter-Asperity Cavitation , 2001 .

[20]  K. Johnson.  Contact Mechanics: Frontmatter , 1985 .

[21]  R. Bosma,et al.  The Influence of Longitudinal and Transverse Roughness on the Elastohydrodynamic Lubrication of Circular Contacts , 1988 .

[22]  Xiaolan Ai,et al.  The effects of surface texture on EHL point contacts , 1996 .

[23]  Michel Fillon,et al.  Relevance of the thermoelastohydrodynamic model in the analysis of a plain journal bearing subjected to severe operating conditions , 2004 .

[24]  A. Love.  The Stress Produced in a Semi-Infinite Solid by Pressure on Part of the Boundary , 1929 .

[25]  Xiaofei Jiang,et al.  A mixed elastohydrodynamic lubrication model with asperity contact , 1999 .

[26]  Sy-Wei Lo.  A Study on Flow Phenomena in Mixed Lubrication Regime by Porous Medium Model , 1994 .

[27]  Dong Zhu,et al.  Virtual Texturing: Modeling the Performance of Lubricated Contacts of Engineered Surfaces , 2005 .

[28]  Shangwu Xiong,et al.  Finite element method for mixed elastohydrodynamic lubrication of journal‐bearing systems , 2004 .

[29]  Leon M Keer,et al.  An Efficient Method of Analyzing the Effect of Roughness on Fatigue Life in Mixed-EHL Contact , 2003 .

[30]  Dong Zhu,et al.  A Full Numerical Solution to the Mixed Lubrication in Point Contacts , 2000 .