A Theory of Lubrication by Microirregularities

Hamilton, Drew; Walowit, J. A.; Allen, Charles M.

doi:10.1115/1.3645799

Cited by 476 publications

(309 citation statements)

References 0 publications

Supporting

Mentioning

279

Contrasting

Unclassified

Order By: Relevance

“…In consequence, the pressure drop over the diverging region of the dimple is limited, and hence, the pressure rise over the converging region of the dimple is greater. This asymmetric pressure distribution over the dimple region makes the average gas pressure greater than the ambient atmospheric pressure [1,5]. As well as liquid lubrication, in the case of gas lubrication using surface texturing, the asymmetric pressure distribution in which the pressure rise over the converging region of the dimple is greater than the pressure drop over the diverging region of the dimple also appears in the dimple region under some conditions.…”

Section: Mechanism Of High Gas Pressure Generationmentioning

confidence: 99%

“…However, the pressure over the diverging region cannot be lower than the pressure at which cavities are formed in the liquid. Therefore, the pressure rise over the converging region is greater than the pressure drop over the diverging region, and then the pressure averaged over the whole surface becomes higher than the ambient pressure [1,5].…”

Section: Introductionmentioning

confidence: 99%

“…Many studies on surface texturing have achieved improvements in tribological performance of sliding surfaces [1][2][3][4][5][6][7]. Surface texturing is expected to have three effects on tribological performance.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mechanism of Levitation of a Slider with a Micro/Nanoscale Surface Structure on a Rotating Disk

et al. 2014

View full text Add to dashboard Cite

It has been previously reported that the friction between a partially polished diamond-coated surface and a metal surface was drastically reduced to zero in the atmosphere as relative speed was increased (Nakamori et al. in Diam Relat Mater 14:2122-2126, 2005. On the other hand, it has also been reported that laser-textured surfaces have good tribological performance in the case of gas lubrication (Kligerman and Etsion in Tribol Trans 44: [472][473][474][475][476][477][478] 2001). The surfaces in the aforementioned two cases have a micro/nanoscale structure. It is expected that both surfaces are levitated by a high-pressure gas film between sliding surfaces by the same mechanism. In the present work, the mechanism of high gas pressure generation is clarified by the performance of numerical simulations and by theoretical analysis. The following two features of pressure distributions on textured surfaces were found to induce high gas pressure. First, gas pressure increases in the direction of the counter surface's motion over the dimple region. Second, the pressure distribution over the flat region is convex upward, and hence, the high pressure obtained at the outlet of the dimple is maintained for a long distance in the flat region. The causes of such pressure distributions are herein explained analytically. The governing factor of pressure distributions and the optimal dimple location in the period of the repeated surface pattern are also discussed. Furthermore, the knowledge obtained here is utilized to design the surface structure to obtain high gas pressure.

show abstract

Section: Mechanism Of High Gas Pressure Generationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mechanism of Levitation of a Slider with a Micro/Nanoscale Surface Structure on a Rotating Disk

et al. 2014

View full text Add to dashboard Cite

show abstract

“…For many decades, considerable effort has been directed toward investigating the mechanisms of textured features from the perspective of hydrodynamic lubrication theory. The earliest and most important mechanism proposed is termed "micro wedge action" in this paper [1][2][3][4], which generates hydrodynamic pressure at the local convergent film shape of the textured features with cavitation at the divergent shape of the features. However, the validity of the load-carrying capacity that is developed by the micro wedge action is doubtful.…”

Section: Introductionmentioning

confidence: 99%

On the Magnitude of Load-Carrying Capacity of Textured Surfaces in Hydrodynamic Lubrication

2015

View full text Add to dashboard Cite

This paper investigates the magnitude of the load-carrying capacity enabled by textured feature in hydrodynamic lubrication. The numerical model is a two-dimensional fixed pad bearing with a single dimple. The Reynolds equation was numerically solved using the Elrod algorithm. Two boundary conditions at the inlet and outlet were compared: a periodic boundary condition and an atmospheric boundary condition. The load-carrying capacity for the atmospheric boundary condition is negative while that for the periodic boundary condition is positive when a dimple is located at the centre of the lubricated area. The atmospheric boundary condition, when a dimple is located on the inlet side and is opened to the outside, exhibits greater load-carrying capacity than that in the enclosed dimple case.

show abstract

“…It also has a major impact on applications involving thermal or electrical resistance, fluid dynamics, noise and vibration control, dimensional tolerance, and abrasive processes, among others. The theoretical analysis of rough surfaces in lubrication dates back to when Hamilton, Wallowit, and Allen (1966) developed a theory of hydrodynamic lubrication between two parallel surfaces with surface roughness on one or both of the surfaces. Tzeng and Saibel (1967) utilized the stochastic approach to study the effect of one-dimensional transverse surface roughness on a slider bearing.…”

Section: Introductionmentioning

confidence: 99%

Effect of Slip Velocity on Magnetic Fluid Lubrication of Rough Porous Rayleigh Step Bearing

Shukla¹,

Deheri²

2013

J MECH ENG SCI

View full text Add to dashboard Cite

This article aims to analyze the performance of a magnetic-fluid-based porous rough step bearing considering slip velocity. The Neuringer-Rosensweig model governs the fluid flow while the velocity slip is modeled by the method of Beavers and Joseph. The bearing surfaces are assumed transversely rough and the transverse surface roughness of the bearing surfaces is characterized by a stochastic random variable with non-zero mean, variance, and skewness. With the usual assumptions of hydrodynamic lubrication, the related stochastically averaged Reynolds' equation for the fluid pressure is solved with appropriate boundary conditions, which is then used to calculate the loadcarrying capacity. It is found that although the bearing suffers owing to transverse surface roughness, the performance of the bearing system can be improved to some extent by the positive effect of magnetization, considering the slip parameter at the minimum; at least in the case of negatively skewed roughness. A comparison of this paper with some established investigations indicates that here, the reduction of loadcarrying capacity due to porosity and slip velocity is comparatively less, especially, when negative variance occurs. In augmenting the performance of the bearing system, the step ratio plays a central role, even if the slip parameter is at the minimum.

show abstract

A Theory of Lubrication by Microirregularities

Cited by 476 publications

References 0 publications

Mechanism of Levitation of a Slider with a Micro/Nanoscale Surface Structure on a Rotating Disk

Mechanism of Levitation of a Slider with a Micro/Nanoscale Surface Structure on a Rotating Disk

On the Magnitude of Load-Carrying Capacity of Textured Surfaces in Hydrodynamic Lubrication

Effect of Slip Velocity on Magnetic Fluid Lubrication of Rough Porous Rayleigh Step Bearing

Contact Info

Product

Resources

About