scholarly journals A mixed lubrication model incorporating measured surface topography. Part 1: Theory of flow factors

2009 ◽  
Vol 224 (4) ◽  
pp. 335-351 ◽  
Author(s):  
F Sahlin ◽  
R Larsson ◽  
A Almqvist ◽  
P M Lugt ◽  
P Marklund
Keyword(s):  
Surface Topography ◽  
Mixed Lubrication ◽  
Theory Of Flow

Changes in Surface Topography with Running-In

1968 ◽  
Vol 183 (16) ◽  
pp. 57-65 ◽  
Author(s):  
R. Østvik ◽  
H. Christensen
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Surface Topography ◽  
Mixed Lubrication ◽  
Contact Conditions ◽  
Line Contacts

The paper will describe the results of an experimental study of changes in surface roughness and contact conditions as running-in and wear take place. Line contacts under conditions of mixed lubrication in both sliding and sliding with rolling have been studied.

Effect of Surface Topography on Mixed Lubrication Film Under Transient Conditions

2009 ◽  
Author(s):  
Ivan Krupka ◽  
Martin Hartl ◽  
Petr Svoboda
Keyword(s):  
Surface Topography ◽  
Film Formation ◽  
Surface Damage ◽  
Mixed Lubrication ◽  
Real Surface ◽  
Transient Conditions ◽  
Lubrication Film ◽  
Lubricated Contacts ◽  
Start Up ◽  
Ball Surface

Surface topography plays an important role in the efficiency of lubricated contacts formed between highly loaded machine parts. Gears, rolling bearings, cam and followers etc. subjected to high loads and/or slow speeds are operated under mixed lubrication when lubrication film is not able to completely separate rubbing surfaces. Such an effect becomes even more serious under transient conditions that bring the risk of the surface damage because of asperities interactions. This paper focuses on the effects of both artificially produced and real roughness features on mixed lubrication film formation during start up motion of non-conformal contacts operated under rolling/sliding conditions. The observation of the effects of surface dents artificially produced on the ball surface helped to understand better the behavior of real surface topography. It was found that the presence of shallow surface features can help to separate mixed lubricated rubbing surfaces more efficiently than it could be suggested from the results obtained with smooth surfaces.

Load-Carrying Properties of Metal Dialkyl Dithiophosphates: Application of Electron Probe Microanalysis

1968 ◽  
Vol 183 (16) ◽  
pp. 35-49
Author(s):  
E. S. Forbes ◽  
K. G. Allum ◽  
H. B. Silver
Keyword(s):  
Surface Layer ◽  
Surface Topography ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Mixed Lubrication ◽  
Wear Scar ◽  
Element Content ◽  
Extreme Pressure ◽  
Load Carrying ◽  
Dialkyl Dithiophosphates

The surface topography and the nature of the surface layer of wear scars obtained with Bi(III), Pb(II), Cd(II), Ni(ll), and Zn(II) di-(4-methylpentyl-2) dithiophosphates, using the four-ball machine, have been studied using an electron probe microanalysis (EPMA) technique. The results show that the nature of the dithiophosphate markedly affects the surface topography, element content, and distribution of the wear scar in both the extreme pressure and mixed lubrication or antiwear regions. The implication of these EPMA results on the load-carrying mechanism of metal dialkyl dithiophosphates is discussed.

Load Distribution Analysis of Journal Bearings Operating Under Mixed Lubrication Conditions

1992 ◽  
Author(s):  
A. Ramamohana Rao ◽  
P. V. Mohanram
Keyword(s):  
Surface Topography ◽  
Journal Bearings ◽  
Mixed Lubrication ◽  
Radius Of Curvature ◽  
Distribution Analysis ◽  
Wear Process ◽  
Wear Life ◽  
Limiting Load ◽  
Asperity Contacts

Abstract When the lubricant film that separates two loaded members becomes thin enough, the asperities on the surfaces begin to interfere. Hydrodynamic journal bearings invariably experience this phenomenon during starting and stopping which is called mixed lubrication. In this case, a part of the applied load is carried by the hydrodynamic action of the fluid film and the remainder through asperity contacts. The part of the load supported by the asperities is significant in that it determines the wear life of the bearing to a large extent. In this work, analytical procedures for the determination of these two components of load based on statistical nature of surface topography have been developed. An algorithm for the estimation of limiting load from wear consideration has been presented. The effect of variation of typical surface topography parameters which undergo change during wear process viz. standard deviation of profile sum, combined radius of curvature of asperities, on hydro-dynamic and asperity load supporting capabilities and true area of contact has been discussed. The computations have been illustrated with experimental data.

Surface Texturing Effect, Characterization and Optimization for Boundary and Mixed Lubrication

2011 ◽  
Author(s):  
B. Podgornik ◽  
M. Sedlacˇek
Keyword(s):  
Surface Topography ◽  
Research Work ◽  
Surface Texturing ◽  
Considerable Change ◽  
Mixed Lubrication ◽  
Design Parameters ◽  
Textured Surfaces ◽  
Tribological Behaviour ◽  
Cavity Depth ◽  
Lubricated Contacts

Under boundary and mixed lubrication surface roughness and topography have significant influence on the tribological behaviour of contact surfaces, where even a small change in surface topography can lead to a considerable change in tribological behaviour. In recent years an effort for better controlling friction and wear has been focused also on the surface topography modification, especially on surface texturing. The aim of the present research work was to investigate the possibility of using roughness parameters kurtosis and skewness as design parameters for optimizing texturing pattern in boundary and mixed lubricated contacts. Results of the investigation performed on groove and dimple textured surfaces under low load low sliding speed conditions confirm correlation between kurtosis and skewness parameters and coefficient of friction. For textured surfaces increase in kurtosis and more negative skewness, obtained by reducing cavity size, increasing cavity depth and decreasing texturing density were found to yield lower friction. Furthermore, kurtosis and skewness were recognized as suitable parameters for textured surfaces optimization. Through virtual texturing effect of different texturing parameters on kurtosis and skewness parameters can be identified and then optimized to result in reduced friction under boundary and mixed lubrication.

Influence of surface functional parameters on friction behavior and elastic–plastic deformation of grinding surface in mixed lubrication state

2018 ◽  
Vol 233 (6) ◽  
pp. 870-883 ◽  
Author(s):  
Bin Zhao ◽  
Song Zhang ◽  
Jianfeng Li
Keyword(s):  
Surface Roughness ◽  
Surface Topography ◽  
Mixed Lubrication ◽  
Surface Model ◽  
Roughness Parameters ◽  
Solid Contact ◽  
Friction Behavior ◽  
Surface Roughness Parameters ◽  
Simulation And Experiment ◽  
Friction Performance

Mixed lubrication is a common lubrication regime in sliding contact and has received much attention in recent research. The influences of surface topography on friction performance in this lubrication state are significant owing to the coexistence of fluid–solid contact and solid–solid contact conditions. First, an accuracy surface model is built based on wavelet transform results. Then, the average Reynolds equation is revised for a grinding surface to be used in simulation. Third, four surface roughness parameters ( Sa, Sbi, S ci, and Svi) are selected to characterize surface topography. Additionally, the impacts on the solid–solid contact area, friction coefficient, and surface flattening are investigated. Finally, optimizations of surface roughness parameters directed toward energy saving and sliding stability are conducted and verified. Simulation and experiment methods are jointly applied to guarantee the accuracy of this research. The result of this study can provide theoretical support for machining contact surfaces.

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