Hydrodynamic Lubrication of Surfaces with Asymmetric Microdimple

Han, Jing; Fang, Liang; Sun, Jinhua; Wang, Yanqing; Ge, Shirong; Zhu, Hua

doi:10.1080/10402004.2011.584364

Cited by 38 publications

(32 citation statements)

References 19 publications

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“…The elasto-hydrodynamic lubrication (EHL) modelling results showed that a larger hydrodynamic lifting effect generated with converging sloped bottom dimples than the flat bottom one [43]. Unanimous conclusions were achieved by another modelling work [44] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 3 were generated from an experimental and numerical work by Shen and Khonsari in 2013 [45]. The aim of their work was to check the lubrication effectiveness of dimples with various internal structures.…”

Section: Introductionmentioning

confidence: 71%

The use of anisotropic texturing for control of directional friction

Lu¹,

Wood²,

Gee

et al. 2017

Tribology International

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This paper presents a study on the influence of anisotropically shaped texture arrays on friction behaviour of an oil lubricated sliding contact, especially on directional friction control based on the diverging and converging characteristics of the textures. Experiments have been conducted on a TE77 reciprocating cylinder-on-plate test rig, where steel rollers were used to slide against steel plate samples with or without textures. A mineral base oil was used to lubricate the contacts. Three geometries of dimples were designed and laser textured on the steel plate samples with varied 3-dimensional features, including Square Flat (SF), Square slope (SS) and Triangular Flat (TF) shapes representing the shape in x-y (top view) and x-z (side view) planes respectively. These shapes were chosen to vary the converging and diverging properties of the lubricated contacts depending on the sliding direction. Relatively large dimple sizes (side length ~ and depth ~ ) have been used in this study to enable observation of the effect and easy control of the texturing process. The texture density has been kept at as most literature suggested. The large dimple sizes resulted that the dimples were not be fully covered by the contact area, i.e. the dimple sides were bigger than the Hertzian contact width of the roller-flat contacts. This has eliminated the 'lift' or 'load bearing' effect discussed in most papers thus focuses on other effects investigated in this study. The results show that beneficial effects of the anisotropic textures present in all lubrication regimes including the boundary, mixed and hydrodynamic lubrications, especially under prevailing boundary lubrication conditions. Using high sampling rate for the friction data during the tests, it was able to study local friction effect due to individual dimple array especially at their leading and trailing edges. The results show that a local friction reduction is observed at the leading while an increase at the trailing edge. Overall directional friction effect of the anisotropic textures has been observed that the converging shape in both y-z plane and the x-y plane reduces friction. Furthermore, it was found that the triangular shape dimples have a greater local frictional response at each dimple array, while the sloped bottom square dimples have a more significant overall directional fricition effect.

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Section: Introductionmentioning

confidence: 71%

The use of anisotropic texturing for control of directional friction

Lu¹,

Wood²,

Gee

et al. 2017

Tribology International

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“…Deterministically-controlled surface shape, known as texturing, has only recently been shown to improve the friction characteristics of parallel sliding surfaces [3,4]. Additional studies have shown that microtextured surfaces can reduce friction compared to flat plates both numerically [5][6][7][8][9][10] and experimentally [11][12][13][14][15][16][17][18][19]. Multiple mechanisms have been suggested for this, across the different lubrication regimes.…”

Section: Introductionmentioning

confidence: 95%

Shear stress characteristics of microtextured surfaces in gap-controlled hydrodynamic lubrication

Johnston

King

Ewoldt

2015

Tribology International

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“…However, it is known that the inertial forces become significant when the gap height rises. To evaluate this, the Modified Reynolds Number has been introduced in the literature [24][25][26]. This number explicitly compares the viscous force of the gap fluid shear with the inertial forces.…”

Section: ∂ ∂X ρH 3 12ηmentioning

confidence: 99%

Experimental Studies of Lubricant Flow and Friction in Partially Filled Gaps

2018

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Starved lubrication is an important strategy for minimizing the amount of lubricant needed, and also inevitably occurs during idling and fail-safe lubrication. In this regime, however, the flow of the lubricant and the related friction coefficients are yet to be fully understood. This research aims to make fundamental contributions to the understanding of contact mechanics of partially lubricated contacts. Recent experiments with a pin-on-disk tribometer examined the microscopic behavior of partially filled gaps. Using a new experimental setup on a macroscale, new insights into partially filled gaps with rough surfaces were gained. This work presents the systematic analyses of the lubricant flow, friction coefficients, and other variables over a wide range of friction parameters. Distinct friction behaviors were observed, and similar effects occur on both the micro and macroscale. The experimental results show that a typical Stribeck characteristic is visible regarding not only the relative velocity, but also regarding the lubricant filling level in the gap. The fluid exhibits a variety of flow patterns for various velocities and viscosities. The patterns relate to different friction regimes, such as dry friction and mixed lubrication. It is concluded that the filling level is a valid parameter for regulating the transition from dry friction to hydrodynamic lubrication. These findings are quantified regarding the filling level and it is shown that for the identification of the friction regimes the filling level is an independent parameter in addition to the established parameters like speed, viscosity and pressure.

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Hydrodynamic Lubrication of Surfaces with Asymmetric Microdimple

Cited by 38 publications

References 19 publications

The use of anisotropic texturing for control of directional friction

The use of anisotropic texturing for control of directional friction

Shear stress characteristics of microtextured surfaces in gap-controlled hydrodynamic lubrication

Experimental Studies of Lubricant Flow and Friction in Partially Filled Gaps

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