An Analysis of Tribochemical Reactions on Boundary Lubrication Regimes

1999 ◽  
pp. 303-315
Author(s):  
Satoshi Matsunuma
Keyword(s):  
Boundary Lubrication ◽  
Tribochemical Reactions ◽  
Lubrication Regimes

scholarly journals The Influence of Pulling Up on Micropitting Location for Gears with Interference Fit Connections of Their Conical Surface

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1224
Author(s):  
Layue Zhao ◽  
Yimin Shao ◽  
Minggang Du ◽  
Yang Yang ◽  
Jixuan Bian
Keyword(s):  
Boundary Lubrication ◽  
Gear Tooth ◽  
Sliding Contact ◽  
Conical Surface ◽  
Dynamic Loads ◽  
Interference Fit ◽  
Bending Fatigue ◽  
Lubrication Regimes ◽  
Surface Fatigue ◽  
Reducing Gear

Micropitting is a surface fatigue phenomenon that occurs in Hertzian type of rolling and sliding contact that operates in elastohydrodynamic or boundary lubrication regimes and can progress both in terms of depth and extent. If micropitting continues to propagate, it may result in reducing gear tooth accuracy, increasing dynamic loads and noise. Eventually, it can develop into macropitting and other modes of gear failure such as flank initiated bending fatigue. Micropitting has become a particular problem in the gear surface fatigue. Usually micropitting initiates in the dedendum of the driver and driven at the asperities on the surface. However, the authors found for some gears with interference fit connections of their conical surface, micropitting on the pinion occurs in the addendum. This study attempted to find the reason using a 3D–TCA method based on ISO/TR 15144-1 to predict the micropitting and try to understand the key influence likely to affect micropitting location.

Tribochemical reactions of dibenzyl and diphenyl disulphides in boundary lubrication

Wear ◽  
1997 ◽  
Vol 205 (1-2) ◽  
pp. 71-76 ◽  
Author(s):  
S. Plaza ◽  
L.R. Comellas ◽  
L. Starczewski
Keyword(s):  
Boundary Lubrication ◽  
Tribochemical Reactions

Analysis of the Contribution of Adhesion and Ploughing to Shoe-Floor Lubricated Friction in the Boundary Lubrication Regime

2011 ◽  
Author(s):  
Caitlin Moore ◽  
Kurt Beschorner ◽  
Pradeep L. Menezes ◽  
Michael R. Lovell
Keyword(s):  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
Ambient Conditions ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Material Hardness ◽  
Lubrication Layer ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Pin On Disk

Slip and fall accidents cost billions of dollars each year. Shoe-floor-lubricant friction has been shown to follow the Stribeck effect, operating primarily in the boundary and mixed-lubrication regimes. Two of the most important factors believed to significantly contribute to shoe-floor-lubricant friction in the boundary lubrication regime are adhesion and ploughing. Experiments were conducted using a pin-on-disk tribometer to quantify adhesion and ploughing contributions to shoe-floor friction in dry and lubricated conditions. The coefficient of friction between three shoe materials and two floor materials of different hardness and roughness were considered. Experiments were conducted under six lubricants for a sliding speed of 0.01 m/sec at ambient conditions. It was found that the contribution of adhesion and ploughing to shoe-floor-lubricant friction was significantly affected by material hardness, roughness, and lubricant properties. Material hardness and roughness are known to affect adhesion, with increased hardness or increased roughness typically resulting in decreased adhesion. The smoothest shoe material, while also being the hardest, resulted in the greatest adhesional contribution to friction. The roughest material, while also being the softest, resulted in the lowest adhesional contributions under dry conditions. Canola oil consistently resulted in the lowest percent of full adhesion and water consistently resulted in the highest percent of full adhesion, presumably due to the thickness, of the boundary lubrication layer. Ploughing contribution was dependent upon the hardness of the shoe and floor materials. A positive correlation was found between the shoe and floor hardness ratio and ploughing coefficient of friction.

Investigation of the wear of engine journal bearings approaching severe lubrication conditions using a microabrasion tester

2019 ◽  
Vol 233 (12) ◽  
pp. 1939-1949 ◽  
Author(s):  
Andys Hernández-Peña ◽  
Leonardo I Farfan-Cabrera ◽  
Ezequiel A Gallardo-Hernández
Keyword(s):  
Boundary Lubrication ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Mineral Oil ◽  
Constant Load ◽  
Journal Bearings ◽  
Engine Operation ◽  
Lubrication Regimes ◽  
Actual Use ◽  
Steel Balls

Ideally, engine journal bearings are expected to operate under hydrodynamic lubrication regime to limit wear and promote minimal friction by sliding. Nevertheless, engine journal bearings fail since wear caused by severe conditions in actual engine operation, such as start/stop, misalignment, lubricant degradation, overheating, and debris contamination, producing a transition from hydrodynamic to mixed and boundary lubrication regimes and wear increased in both engine journal bearings and crankshaft. Thus, this work aims to study the influence of boundary lubrication, engine mineral oil aging, and debris contamination on wear of engine journal bearings. An adapted microscale abrasion tester using a ball-on-concave flat configuration was used to reproduce boundary lubrication under controlled conditions. Steel balls having a similar surface than crankshafts and concave flat samples cut from actual engine journal bearings were tested. The tests were run under boundary lubrication at a constant load, speed, and sliding distance at 26 ℃ and 100 ℃ using separately clean fresh and aged engine mineral oil, and then, tests were conducted using the oils contaminated with hard abrasive particles. The engine mineral oil was degraded by a laboratory aging process approaching oxidation of an engine mineral oil used in actual use conditions. Oxidation, additives depletion and changes in viscosity were evaluated. The wear volumes and scar morphologies of engine journal bearing samples were analyzed. The results suggested that high temperature was the main contributor for wear increase in engine journal bearings, while oil aging and debris did not influence considerably on the wear. However, the oils contaminated with hard particles produced a wear decrease in engine journal bearing samples but increased wear in rotary balls.

scholarly journals Theoretical and Experimental Investigation on Friction in Lubricated Line Contacts with Different Materials and Textures in Presence of Wear

2016 ◽  
Vol 681 ◽  
pp. 142-154 ◽  
Author(s):  
Francesca Di Puccio ◽  
Enrico Ciulli
Keyword(s):  
Surface Roughness ◽  
Experimental Investigation ◽  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Flat Surface ◽  
Surface Conditions ◽  
Lubrication Regimes ◽  
Line Contacts ◽  
Lubrication Conditions ◽  
Theoretical Procedure

An experimental investigation on the friction coefficient in line contacts under mixed and boundary lubrication regimes is described. Rectangular contacts between cylindrical specimens and the flat surface of discs of different material and surface roughness combinations were analyzed. Very low Stribeck numbers have been considered, resulting also in low dimensionless film thickness, so that the morphology of the surfaces and the material had a remarking role. In this work, the theoretical procedure for assessing the friction coefficient in the tested cases is described and compared to experimental results. Additionally, wear effects obtained in boundary lubrication conditions are shown. The surface conditions are put in relation with some particular trends of the friction coefficient obtained for certain combinations of materials and roughness.

Paper 12: Modes of Lubrication in Human Joints

1966 ◽  
Vol 181 (10) ◽  
pp. 45-54 ◽  
Author(s):  
D. Dowson
Keyword(s):  
Articular Cartilage ◽  
Synovial Fluid ◽  
Boundary Lubrication ◽  
Bearing Material ◽  
Modes Of Operation ◽  
Basic Properties ◽  
Lubrication Regimes ◽  
Basic Characteristics ◽  
Human Joints ◽  
Lubrication Conditions

The various lubrication regimes encountered in engineering are listed and the basic characteristics of each regime described. This survey covers hydrodynamic, elastohydrodynamic, mixed, and boundary lubrication conditions. The geometric, kinematic, and loading conditions in human joints are examined, and the basic properties of synovial fluid and articular cartilage, as the lubricant and bearing material respectively, noted. An assessment of the hydrodynamic, boundary, weeping, and elastohydrodynamic modes of operation which have been proposed as explanations of the performance of human joints is presented.

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