Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 39) Show all publications
Tosic, M., Larsson, R., Jovanović, J., Lohner, T., Björling, M. & Stahl, K. (2019). A Computational Fluid Dynamics Study on Shearing Mechanisms in Thermal Elastohydrodynamic Line Contacts. Lubricants, 7(8), Article ID 69.
Open this publication in new window or tab >>A Computational Fluid Dynamics Study on Shearing Mechanisms in Thermal Elastohydrodynamic Line Contacts
Show others...
2019 (English)In: Lubricants, E-ISSN 2075-4442, Vol. 7, no 8, article id 69Article in journal (Refereed) Published
Abstract [en]

A computational fluid dynamics (CFD) model of the thermal elastohydrodynamically lubricated (EHL) line contact problem has been developed for the purpose of exploring the physical processes that occur inside a thin EHL film subjected to shearing motion. The Navier–Stokes equations are solved by using the finite volume method (FVM) in a commercial CFD software, ANSYS Fluent. A set of user-defined functions (UDF) are used for computing viscosity, density, heat source, temperature of moving surfaces and elastic deformation of the top roller according to well-established equations commonly used in the EHL theory. The cavitation problem is solved by taking into account multiphase mixture flow. The model combinations of Houpert and Ree–Eyring and of Tait and Carreau were used for modeling the non-Newtonian behavior of Squalane and the results were compared. Both rheological models suggest the existence of shear-band and plug-flow at high fluid pressure. Due to the differences in viscosity at GPa-level pressure, the chosen model has substantial influence on the computed shear stress and temperature distributions in the high-pressure region. This shows the importance of using correct rheology information in the whole range of pressure, temperature, and shear strain rate.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
EHL, TEHL, CFD, finite volume, non-Newtonian fluid, cavitation, rheology, fluent
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-75819 (URN)10.3390/lubricants7080069 (DOI)000482956800010 ()2-s2.0-85071170341 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-09-09 (johcin)

Available from: 2019-09-03 Created: 2019-09-03 Last updated: 2019-09-13Bibliographically approved
Hua, J., Björling, M., Grahn, M., Larsson, R. & Shi, Y. (2019). A smart friction control strategy enabled by CO2 absorption and desorption. Scientific Reports, 9(1), Article ID 13262.
Open this publication in new window or tab >>A smart friction control strategy enabled by CO2 absorption and desorption
Show others...
2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, no 1, article id 13262Article in journal (Refereed) Published
Abstract [en]

Intelligent control of friction is an attractive but challenging topic and it has rarely been investigated for full size engineering applications. In this work, it is instigated if it would be possible to adjust friction by controlling viscosity in a lubricated contact. By exploiting the ability to adjust the viscosity of the switchable ionic liquids, 1,8-Diazabicyclo (5.4.0) undec-7-ene (DBU)/ glycerol mixture via the addition of CO2, the friction could be controlled in the elastohydrodynamic lubrication (EHL) regime. The friction decreased with increasing the amount of CO2 to the lubricant and increased after partial releasing CO2. As CO2 was absorbed by the liquid, the viscosity of the liquid increased which resulted in that the film thickness increased. At the same time the pressure-viscosity coefficient decreased with the addition of CO2. When CO2 was released again the friction increased and it was thus possible to control friction by adding or removing CO2.

Place, publisher, year, edition, pages
Springer, 2019
National Category
Chemical Process Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Chemical Technology; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-76046 (URN)10.1038/s41598-019-49864-w (DOI)000485680900059 ()31519987 (PubMedID)2-s2.0-85072208170 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-09-18 (johcin)

Available from: 2019-09-18 Created: 2019-09-18 Last updated: 2019-10-25Bibliographically approved
Björling, M. & Shi, Y. (2019). DLC and Glycerol: Superlubricity in Rolling/Sliding Elastohydrodynamic Lubrication. Tribology letters, 67(1), Article ID 23.
Open this publication in new window or tab >>DLC and Glycerol: Superlubricity in Rolling/Sliding Elastohydrodynamic Lubrication
2019 (English)In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 67, no 1, article id 23Article in journal (Refereed) Published
Abstract [en]

Low friction is one of the most important parameters for the development of machine components and machines with high efficiency. Many of the common machine components of today such as gears, rolling element bearings and cam-followers are defined by their non-conformal contacts leading to high-contact pressures, typically 1–4 GPa. The lubrication of such contacts is usually called elastohydrodynamic lubrication (EHL). Diamond-like carbon (DLC) coatings and glycerol have individually been shown to produce low friction in boundary, mixed and full film lubrication. A few studies have been conducted using both glycerol and DLC-coated surfaces to achieve even lower friction in pure sliding boundary-lubricated contacts. However, the literature is lacking studies of how the combination of glycerol and DLC performs in non-conformal rolling/sliding contacts where many common machine components operate. Such a study is presented in this article where a ball-on-disc test rig is used to investigate the performance of the combination of DLC and glycerol at pressures up to 1.95 GPa at various entrainment speeds and slide-to-roll ratios. The investigation shows that the DLC-glycerol combination provides very low friction values, in some cases, below the superlubricity threshold of 0.01, possibly shown for the first time at such high pressure in a non-conformal rolling/sliding contact. The low friction mechanism in full film lubrication is a combination of the low pressure-viscosity and high temperature-viscosity sensitivity of glycerol in combination with thermal insulation of the DLC coating and is presented as thermally assisted liquid superlubricity.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Traction, EHL, Coatings, friction reducing, Superlubricity, Friction, Thermal effects in EHL, DLC, Glycerol
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-72541 (URN)10.1007/s11249-019-1135-1 (DOI)000455190400002 ()2-s2.0-85059784212 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-01-25 (inah)

Available from: 2019-01-14 Created: 2019-01-14 Last updated: 2019-01-25Bibliographically approved
Björling, M., Habchi, W., Bair, S., Larsson, R. & Marklund, P. (2019). Erratum: Towards the true prediction of EHL friction (ed.). Tribology International, 133, 297-297
Open this publication in new window or tab >>Erratum: Towards the true prediction of EHL friction
Show others...
2019 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 133, p. 297-297Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-73121 (URN)10.1016/j.triboint.2018.10.018 (DOI)
Note

Erratum in: Tribology International, vol. 66, p.19-26, DOI:10.1016/j.triboint.2013.04.008

Available from: 2019-03-06 Created: 2019-03-06 Last updated: 2019-03-06Bibliographically approved
Hansen, J., Björling, M. & Larsson, R. (2019). Mapping of the lubrication regimes in rough surface EHL contacts. Tribology International, 131, 637-651
Open this publication in new window or tab >>Mapping of the lubrication regimes in rough surface EHL contacts
2019 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 131, p. 637-651Article in journal (Refereed) Published
Abstract [en]

Understanding film formation in rough surface elastohydrodynamically lubricated (EHL) contacts have been an ongoing pursuit in lubrication science for more than half a century. This study furthers that quest by establishing a single combined friction and electrical contact resistance map that forms a clear and comprehensive overview of the lubrication performance. A ball-on-disc machine was operated under a wide variety of heavily loaded rolling/sliding contact conditions. Results show that while sweeping the contact over the SRR- and entrainment speed-domain, the primary sweep direction significantly affects running-in and consequently the transition from full-film to the mixed lubrication regime. Such knowledge sheds new light into the mechanisms that governs EHL film formation and the concurrent interplay with the mixed lubricated friction coefficient.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Rough surface EHL, Friction, Stribeck curve, Running-in
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-71681 (URN)10.1016/j.triboint.2018.11.015 (DOI)000456766000062 ()2-s2.0-85057507855 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-12-05 (johcin)

Available from: 2018-11-20 Created: 2018-11-20 Last updated: 2019-02-21Bibliographically approved
Vrček, A., Hultqvist, T., Baubet, Y., Björling, M., Marklund, P. & Larsson, R. (2019). Micro-pitting and wear assessment of engine oils operating under boundary lubrication conditions. Tribology International, 129, 338-346
Open this publication in new window or tab >>Micro-pitting and wear assessment of engine oils operating under boundary lubrication conditions
Show others...
2019 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 129, p. 338-346Article in journal (Refereed) Published
Abstract [en]

Current state-of-the-art engine oils tend to enhance micro-pitting damage in rolling contacts under certain operating conditions. ZDDP anti-wear additive was shown to promote such behavior. However, in order to optimize an engine oil formulation for rolling contacts, further studies are needed to assess engine oils in terms of micro-pitting and wear damage. This investigation studies the micro-pitting and wear performance of a number of engine oils for rolling contacts in a ball-on-disc configuration under conditions prevalent in crankshaft roller bearing applications. Based on the results it was concluded that an engine oil containing higher blend of PAO base oil compared to the oil mixture of Group III and PAO has a lower tendency towards micro-pitting and wear.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-70731 (URN)10.1016/j.triboint.2018.08.032 (DOI)000447575600028 ()2-s2.0-85052642062 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-09-24 (inah)

Available from: 2018-09-03 Created: 2018-09-03 Last updated: 2018-11-01Bibliographically approved
Vrček, A., Hultqvist, T., Baubet, Y., Björling, M., Marklund, P. & Larsson, R. (2019). Micro-Pitting and Wear Assessment of PAO vs Mineral-Based Engine Oil Operating under Mixed Lubrication Conditions: Effects of Lambda, Roughness Lay and Sliding Direction. Lubricants, 7(5), Article ID 42.
Open this publication in new window or tab >>Micro-Pitting and Wear Assessment of PAO vs Mineral-Based Engine Oil Operating under Mixed Lubrication Conditions: Effects of Lambda, Roughness Lay and Sliding Direction
Show others...
2019 (English)In: Lubricants, E-ISSN 2075-4442, Vol. 7, no 5, article id 42Article in journal (Refereed) Published
Abstract [en]

Under certain operating conditions, rolling contacts have been shown to experience some challenges when lubricated with engine oils containing zinc dialkyldithophosphate (ZDDP) anti-wear additive. In order to better understand the main damage mechanisms during various operating conditions, further studies are needed. This article studies micro-pitting and wear damages of bearing steel surfaces under mixed lubrication conditions in a ball-on-disc setup, lubricated with different engine oils. Based on the results, micro-pitting and wear damage is shown to be highly case-dependent. In general, PAO-based engine oil tends to eliminate micro-pitting damage compared to mineral-based engine oil at less severe lubricating conditions. Moreover, a critical lambda was found for both oils, where the highest micro-pitting damage was observed. 

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
micro-pitting, ZDDP, mild wear, surface-initiated fatigue
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-75059 (URN)10.3390/lubricants7050042 (DOI)000470959700003 ()2-s2.0-85066431252 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-06-27 (johcin)

Available from: 2019-06-27 Created: 2019-06-27 Last updated: 2019-06-27Bibliographically approved
Björling, M., Habchi, W., Bair, S., Larsson, R. & Marklund, P. (2018). Correction to: Friction reduction in elastohydrodynamic contacts by thin-layer thermal insulation (ed.) [Letter to the editor]. Tribology letters, 66(4), 1-1
Open this publication in new window or tab >>Correction to: Friction reduction in elastohydrodynamic contacts by thin-layer thermal insulation
Show others...
2018 (English)In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 66, no 4, p. 1-1Article in journal, Letter (Refereed) Published
Abstract [en]

The original version of this article unfortunately contained a mistake. The correct information is given below. [ABSTRACT FROM AUTHOR]  Copyright of Tribology Letters is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-71140 (URN)10.1007/s11249-018-1079-x (DOI)
Available from: 2018-10-08 Created: 2018-10-08 Last updated: 2018-10-08Bibliographically approved
Hansen, J., Björling, M. & Larsson, R. (2018). Improved performance by ionic additives in hydrocarbon base fluids for mixed-rolling/sliding contacts. In: : . Paper presented at The 18th Nordic Symposium on Tribology – NORDTRIB, Uppsala, Sverige, June 18-21.
Open this publication in new window or tab >>Improved performance by ionic additives in hydrocarbon base fluids for mixed-rolling/sliding contacts
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:ltu:diva-75805 (URN)
Conference
The 18th Nordic Symposium on Tribology – NORDTRIB, Uppsala, Sverige, June 18-21
Available from: 2019-09-02 Created: 2019-09-02 Last updated: 2019-09-02
Hansen, J., Björling, M., Minami, I. & Larsson, R. (2018). Performance and mechanisms of silicate tribofilm in heavily loaded rolling/sliding non-conformal contacts. Tribology International, 123, 130-141
Open this publication in new window or tab >>Performance and mechanisms of silicate tribofilm in heavily loaded rolling/sliding non-conformal contacts
2018 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 123, p. 130-141Article in journal (Refereed) Published
Abstract [en]

Lubricant performance is vital as heavy-duty gear manufacturers increase power density in their efforts towards increased efficiency. In this work, a recently developed ionic liquid is introduced as a multifunction additive for use in hydrocarbon base fluid. A ball-on-disc tribological test machine was used to evaluate friction and wear in heavily loaded mixed rolling/sliding conditions. The novel multifunctional additive is benchmarked against conventional axle-gear oil additives, and results shows excellent tribological performance in terms of friction and wear. Post-test surface analysis of the wear scars revealed a silicate based tribofilm derived from the novel ionic additive, contrary to conventional phosphorous and/or sulfur based. The silicate tribofilm is correlated to a significantly increased wear resistance and vastly improved running-in performance.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-67928 (URN)10.1016/j.triboint.2018.03.006 (DOI)000431161600014 ()2-s2.0-85043594654 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-03-20 (andbra)

Available from: 2018-03-14 Created: 2018-03-14 Last updated: 2018-06-11Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4271-0380

Search in DiVA

Show all publications