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Journal ArticleDOI

Lubrication of Porous Journal Bearings

01 Jan 1972-Journal of Lubrication Technology (American Society of Mechanical Engineers)-Vol. 94, Iss: 1, pp 69-73
About: This article is published in Journal of Lubrication Technology.The article was published on 1972-01-01. It has received 63 citations till now. The article focuses on the topics: Lubrication & Air bearing.
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Journal ArticleDOI
TL;DR: In this article, the LIGA MEMs manufacturing method is used to fabricate a sample thrust bearing surface with a hexagonal array of positive asperities, which can have heights of 3-100 μm.
Abstract: Deterministic micro asperities show potential for enhancement of lubrication in conformal contacts as found in many bearing and seal designs. Several manufacturing methods have been proposed for deterministic micro asperities. Of these, laser texturing has emerged as the most viable option. This paper proposes the LIGA MEMs manufacturing method as an alternative. Using LIGA, surfaces with patterned micron sized surface features of arbitrary cross section (cylindrical, hex, triangular, etc.) can be fabricated from electroplated nickel, gel-cast silicon nitride, or plastic. The resulting asperities can be positive (protuberances) or negative (recesses) and can have heights (depths) from 1-1000 microns and be patterned over surface areas up to about 150 mm X150 mm. In this paper, the LIGA method is used to fabricate a sample thrust bearing surface with a hexagonal array of positive asperities. The resulting asperities are 550 μm in average diameter, 165 μm in edge-to-edge spacing and have heights of 3-100 μm. Surface metrology indicates submicron accuracy of form and 13 nm Ra roughness on the asperity tops (land). Tribology testing in a nonpressurized oil bath indicates full film conditions and shows a 14-22% reduction in friction coefficient for a thrust surface covered with the micro asperities. A model confirms the experimental trends and indicates the potential to further reduce the friction coefficient by about 60% through optimization of the asperity geometry and layout.

71 citations

Journal ArticleDOI
TL;DR: In this paper, a numerical solution for the hydrodynamic lubrication of finite porous journal bearings considering the flexibility of the liner is introduced, and the Brinkman-extended Darcy equations and the Stokes' equations are utilized to model the flow in the porous region and fluid film region, respectively.

42 citations

Journal ArticleDOI
TL;DR: In this article, a porous media model is developed which can be applied to thin film lubrication problems, where the microstructure of bearing surfaces is modeled as porous layers attached to the impermeable substrate.
Abstract: In this study, a porous media model is developed which can be applied to thin film lubrication problems. The microstructure of bearing surfaces is modeled as porous layers attached to the impermeable substrate. The Brinkman-extended Darcy equations and Stokes' equations are utilized to model the flow in the porous region and fluid film region, respectively. The stress jump boundary condition at the porous media/fluid film interface and effects of viscous shear are included in deriving the modified Reynolds equation. The present model can correct and modify a previous study based on the Darcy model with slip-flow effects or another based on the Brinkman-extended Darcy model with stress continuity at the porous media/fluid film interface. In the results, the effects of material properties: viscosity ratio (α i 2 ), thickness of porous layer (Δ i ), permeability (K,), stress jump parameter (β i ), on the velocity distributions, and performance of one-dimensional converging wedge problems are discussed.

35 citations

Journal ArticleDOI
TL;DR: In this article, a numerical simulation is presented for the thermo-hydrodynamic self-lubrication aspect analysis of porous circular journal bearing of finite length with sealed ends, which consists in analyzing the thermal effects on the behavior of circular porous journal bearings.

34 citations


Cites methods from "Lubrication of Porous Journal Beari..."

  • ...Thus, equations [1-5] in non-dimensional form are - Reynolds equations...

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  • ...made valuable contributions to this field [3-6]....

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Journal ArticleDOI
TL;DR: Theoretical study of porous slider bearing with couple stress fluid as lubricant is made and the lubrication qualities of couple stress fluids are examined in this article, where analytical expressions for load capacity, frictional force and the centre of pressure are derived.
Abstract: Theoretical study of porous slider bearing with couple stress fluid as lubricant is made and the lubrication qualities of couple stress fluid are examined. The lower surface is covered by a thin porous material and the upper one, having arbitrary shape, moves in its own plane with constant velocity. Analytical expressions for load capacity, frictional force and the centre of pressure are derived. It yields increase in, load capacity and ensures the decrease in coefficient of friction. The problem is also discussed in the context of various geometries viz, (1) Rayleigh step bearings and (2) inclined slider bearings. Bounds on flow rate, frictional coefficient, centre of pressure and time-height relation are obtained and compared with classical case, Gross [1]. Suitable design parameters are predicted for the efficient lubrication of slider bearings.

28 citations