Micro Textures in Concentrated-Conformal-Contact Lubrication: Effect of Distribution Patterns

Abstract

Micro-scale textures may be engineered into surfaces for lubrication performance improvement. It is expected that a carefully chosen texture helps retain lubricant and enhances the hydrodynamic effect at the interface. The concept of model-based virtual texturing enables textured surfaces to be generated and ''tested'' through numerical simulations. This paper reports virtual texturing and simulation of a group of textured surfaces in a lubricated concentrated contact. The focus of the study is on the selection of texture distribution patterns based on their lubrication performance. Patterns of fishbone, sinusoidal, triangular, and honeycomb distributions have been investigated. The effects of texture direction, orientation angle, feature continuity, and aspect ratio are also studied. The results indicate that, for the given material and geometry system under the given conditions in the present work, the textures generating the strongest hydrodynamic lifting are short grooves with a small aspect ratio and sinusoidal waves of a small wavelength/amplitude ratio propagating in the motion direction.

Lubricated MEMS: effect of boundary slippage and texturing

“…The primary parameters of the lubricated sliding contact are given as follows: sliding velocity U is 1 m/s (the corresponding Reynolds number R e is 1 [23,25,29,31,33], and the critical shear stresses range from 0 to 1,000 Pa, reasonable values based on literature [34][35][36][37][38]. All parameters and the range in which they are varied for all cases investigated in the present study are summarized in Table 1.…”

“…The range of Reynolds numbers tested is from 0.001 to 20. In the following simulations, the critical shear stresses range from 0-1,000 Pa, reasonable values based on literature [17][18][41][42][43] are used, and the slip coefficient α varies from 0 to 0.1 m 2 s/kg (the corresponding slip length is 1x10 -4 m) based on the results published in literature [25,28,31,37]. All parameters and the range in which they are varied for all cases investigated in the present study are summarized in Table 1.…”

“…As noted, most of the results from the literature review show that there is a little effect of the texture shape on the tribological performances of the LST (laser surface textured) surfaces. In addition, based on recent publications [37,38], in relation to the orientation effect of the texture on sliding surfaces, it was stated that for noncircular texture shapes, which are similar to what is used in this study, the strongest hydrodynamic load support is offered when its main axis is perpendicular to the sliding direction.…”

“…During the past decade, with the development of advanced experimental techniques, numerous experiments have shown that boundary slip can occur at both a hydrophobic surface [14,18,[35][36][37][38] and a hydrophilic surface [15,16,38,39]. For most hydrophilic surfaces, however, no slip occurs.…”

“…Bayada and Meurisse [36], using a relatively simple simulation, demonstrated that the pressure distribution induced by deterministic roughness is smaller than that induced by the artificial slip. Rao [37] employed an artificial slip on a stationary surface having a single-groove at a slider and a journal bearing and derived the pressure, the shear stress, stiffness and damping coefficients. The modified Reynolds equation based on the slip length model was solved.…”