Textured Surface Hydrodynamic Lubrication: Discussion

Scaraggi, Michele

doi:10.1007/s11249-012-0025-6

Cited by 34 publications

(36 citation statements)

References 14 publications

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“…i E(x ci ) = E(0): the BEM dilution assumption exactly holds in this case. This disruptive interference, remarkably, explains the success of the BTH in accurately predicting the average flow dynamics of common surface textures [23,26], for example, represented in figure 1b. (b) The polarization of two interacting circular superficial defects embedded in a homogeneous medium…”

Section: On the Bruggeman Effective Medium Approach Applied To Texturmentioning

confidence: 87%

“…The BTH theory has been successfully tested in a number of comparisons with both numerical [23,26,27] and experimental [26] results, showing, in particular, that both friction as well as supported load can be accurately calculated within the model. For a single thrust bearing pad, partially textured with square holes arranged in a square lattice, in figure 14 the cross-section pressure field is shown as a function of the contact position (along the sliding axis) as obtained from independent exact numerical calculations [20] (red dotted curves), and is compared with the predictions (with same texture area density but for circular holes) for the BTH [23] (dashed black line) and cBTH (solid line) theories.…”

Section: Discussionmentioning

confidence: 99%

“…successful comparative studies with both numerical [23,26] and experimental [26,27] results from independent investigations. However, there exist no theoretical arguments supporting the applicability of the BEM approach (which is well known to hold for defects that are randomly distributed in the conducting medium) to an ordered distribution of defects, in our case a lattice of flow conductivity defects.…”

Section: Introductionmentioning

confidence: 93%

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The friction of sliding wet textured surfaces: the Bruggeman effective medium approach revisited

Scaraggi

2015

Proc. R. Soc. A.

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ResearchCite this article: Scaraggi M. 2015 The friction of sliding wet textured surfaces: the Bruggeman effective medium approach revisited. Proc. R. Soc. A 471: 20140739. http://dx.The mean field fluid dynamics and the friction occurring in the wet sliding contact between inhomogeneous surfaces, characterized by a deterministically repeated pattern of microdefects, are modelled within the Bruggeman effective medium theory. By comparing with the results of an accurate numerical homogenization of the flow equations, and with asymptotic solutions, we discuss the validity of the mean field model and its limitations in relation to the occurrence of clustering and interference effects. Finally, an analytical upgrade to the Bruggeman approach, allowing for inclusion of the clustering effect, is presented and discussed.

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Section: On the Bruggeman Effective Medium Approach Applied To Texturmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 93%

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The friction of sliding wet textured surfaces: the Bruggeman effective medium approach revisited

Scaraggi

2015

Proc. R. Soc. A.

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“…We assume that the sliding contact takes place between the partially textured and plain parallel surfaces, under the iso-viscous rigid lubrication regime and isothermal conditions. An analytical model has been developed under these conditions, which accurately describes the texture hydrodynamics [20]. The theoretical model allows for the calculation of the average flow dynamics at the contact interface, in terms of the flow and the shear stress tensorial factors, provided that cavitation is absent or it has a negligible effect (as is usually the case of partial surface textures).…”

Section: Super-bearings With Enhanced Load Support and Low-frictionmentioning

confidence: 99%

“…Although being beneficial to friction reduction, it is shown that an isotropic lattice of circular dimples fails to redirect the lubricant flow because it provides isotropic conductivities [22]. On the other hand, striped superficial defects are well known to produce anisotropic flow redistribution [20,22]. In the case of texturing with micro-grooves extending all over the contact surface (total texturing), a friction increase has been experimentally reported.…”

Section: Super-bearings With Enhanced Load Support and Low-frictionmentioning

confidence: 99%

Non-Uniform Laser Surface Texturing of an Un-Tapered Square Pad for Tribological Applications

et al. 2017

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Femtosecond laser surface micro-texturing has emerged as a promising technology to enhance the tribological properties of different kinds of electromechanical devices. In this research paper, we have exploited the intrinsic flexibility and micrometric accuracy of femtosecond laser ablation to realize complex micro-structural modifications on the surface of a laboratory prototype of a steel thrust bearing (un-tapered) pad. The Bruggeman Texture Hydrodynamics theory (BTH) is employed for the design of the anisotropic and non-uniform texture maximizing the thrust load of the pad prototype. The preliminary experimental results, reported in this work, show that the non-uniform micro-texture largely affects the friction characteristics of the contact. In particular, in agreement with the BTH predictions, the tribo-system shows friction properties that are strongly sensitive to the direction of the sliding speed, as a consequence of the micro-fluid dynamics which are designed to occur only in a specific sliding direction. We suggest that the joint action of virtual prototyping (BTH lubrication theory) and ultrafast laser micro-prototyping can lead to unconventional and impressive results in terms of enhanced or tailored contact mechanics properties of the generic lubricated tribopair.

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Friction Reduction Induced by Elliptical Surface Patterns under Lubricated Conditions

et al. 2017

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Recording Stribeck-like curves is an efficient way to evaluate the frictional performance and efficiency of patterned surfaces. Elliptical patterns with varying area density and structural depth are fabricated by micro-coining on steel substrates (AISI 304). A ball-on-disc tribometer is used to perform unidirectional sliding experiments for the polished reference and the elliptical patterns dependent on the sliding velocity. In this study, a clear connection between structural parameters such as length of long and short axis, aspect ratio, and pitch with the frictional behavior can be found. Comparing patterns with comparable depth and area density underlines that elliptical patterns having larger individual features (increased length of both axes) separated by a larger pitch reduce the COF more significantly. The number of tribologically active individual elliptical structures, recirculation effects of the lubricant, as well as the pattern geometry that may lead to undesired edge effects and stress concentrations need to be taken into consideration to explain those findings. The sample with the smallest structural depth, the smallest area density, and the lowest aspect ratio (A1) leads to the maximum friction reduction (4-fold) for all velocities which underlines the enormous potential of elliptical structures in terms of friction reduction.

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Textured Surface Hydrodynamic Lubrication: Discussion

Cited by 34 publications

References 14 publications

The friction of sliding wet textured surfaces: the Bruggeman effective medium approach revisited

The friction of sliding wet textured surfaces: the Bruggeman effective medium approach revisited

Non-Uniform Laser Surface Texturing of an Un-Tapered Square Pad for Tribological Applications

Friction Reduction Induced by Elliptical Surface Patterns under Lubricated Conditions

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