The Role of Surface Roughness on Lubrication: Numerical and Experimental Analyses

A special issue of Lubricants (ISSN 2075-4442).

Deadline for manuscript submissions: closed (30 June 2020) | Viewed by 6345

Special Issue Editor

Department of Mechanics, Mathematics and Management, Politecnico di Bari, 70126 Bari, Italy
Interests: applied mechanics; tribology; lubrication; contact mechanics; design
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In recent decades, lubrication science has increasingly focused on multi-scale phenomena with the specific aim to correlate what occurs at the micro-scale with the global tribological performance at the macro-scale. Massive research efforts on theoretical significance and engineering interest have occurred in this regard. However, our knowledge of multi-scale lubrication is still far from complete. Specifically, in spite of many analytical, numerical and experimental approaches, an exhaustive description of the role played by the micro-topography of the contacting solids in determining the lubrication performance is still missing. The so-called boundary and mixed lubrication regimes, which are crucially important for applicative and engineering reasons, are indeed marked by a poor theoretical knowledge.

This Special Issue aims to promote advances in this field, in particular, the role played by the roughness in lubrication. We invite authors to submit original research and review articles that will stimulate continuing effort to understand and improve our understanding of multiscale lubrication. We are particularly interested in contributions focusing on lubrication of macro-, micro-, and nano-systems. Potential topics include, but are not limited to the following:

  • Molecular Dynamics (MD) simulation;
  • Stochastic and/or deterministic solution of Reynolds equations for boundary and mixed lubrication;
  • Complementary approaches and the role of cavitation at the micro-scale;
  • The roles of slip length and hydrophobicity at the micro- and meso-scale;
  • Topographical micro-design in boundary and mixed lubrication;
  • The roles of lubricant and solid rheology in multi-scale lubrication;
  • Experimental characterization of tribological performance by means of innovative micro- and nano- tribometers; and
  • Experimental innovative tribo-experiments (e.g., ultrasonic, fluorescence techniques).

Dr. Carmine Putignano
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Lubricants is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Lubrication
  • Friction
  • Roughness
  • Numerical methods
  • Experiments

Published Papers (2 papers)

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Research

13 pages, 1503 KiB  
Article
Numerical Simulation of Static Seal Contact Mechanics Including Hydrostatic Load at the Contacting Interface
Lubricants 2021, 9(1), 1; https://doi.org/10.3390/lubricants9010001 - 23 Dec 2020
Cited by 6 | Viewed by 2645
Abstract
A finite element model of a static seal assembled in its housing has been built and is utilized to study how the seal deforms under varying loading conditions. The total contact load on the sealing surface is balanced by the sealed fluid pressure [...] Read more.
A finite element model of a static seal assembled in its housing has been built and is utilized to study how the seal deforms under varying loading conditions. The total contact load on the sealing surface is balanced by the sealed fluid pressure and the friction between the seal and the housing sidewall perpendicular to the sealing surface. The effect of the sealed fluid pressure between the sealing surfaces was investigated and the simulation showed that the surface profile is distorted due to the hydrostatic pressure. We study the distorted contact profile with varying sealed fluid pressure and propose five parameters to describe the corresponding contact pressure profile. One of these parameters, overshoot pressure, a measure of the difference between maximum contact pressure and the sealed fluid pressure, is an indicator of sealing performance. The simulations performed show different behaviors of the overshoot pressure with sealed fluid pressure for cosinusoidal and parabolic surfaces with the same peak to valley (PV) value. Full article
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27 pages, 3923 KiB  
Article
On Waviness and Two-Sided Surface Features in Thermal Elastohydrodynamically Lubricated Line Contacts
Lubricants 2020, 8(6), 64; https://doi.org/10.3390/lubricants8060064 - 13 Jun 2020
Cited by 5 | Viewed by 3241
Abstract
Machine components are designed to endure increasingly severe operating conditions due to the strive for improved energy efficiency of mechanical systems. Consequently, lubricated non-conformal contacts must rely on thin lubricant films where the influence of surface topography on the lubricating conditions becomes significant. [...] Read more.
Machine components are designed to endure increasingly severe operating conditions due to the strive for improved energy efficiency of mechanical systems. Consequently, lubricated non-conformal contacts must rely on thin lubricant films where the influence of surface topography on the lubricating conditions becomes significant. Due to the complexity of the multiphysical problem, approximate assumptions are often employed to facilitate numerical studies of elastohydrodynamically lubricated (EHL) contacts. In this work, the rough, time dependent, thermal EHL problem is solved with focus on two main analyses. The first analysis focuses on the influence of sinusoidal roughness and the difference between a thermal non-Newtonian approach and an isothermal Newtonian approach. The second analysis is focused on the lubricating mechanisms taking place when two-sided surface features overtake within the thermal EHL contact. The results indicate that the film thickness in the outlet of the contact may be significantly overestimated by an isothermal Newtonian approach and that differences in the high-pressure region may also occur due to viscosity variations in the inlet of the contact. Moreover, for the studied two-sided surface features, it became evident that not only the surface feature combination but also the overtaking position influence the film thickness and pressure variations significantly. Full article
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