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Hultqvist, T., Vrček, A., Prakash, B., Marklund, P. & Larsson, R. (2019). Influence of lubricant pressure response on sub-surface stress in elastohydrodynamically lubricated finite line contacts. Journal of tribology, 141(3), Article ID 031502.
Open this publication in new window or tab >>Influence of lubricant pressure response on sub-surface stress in elastohydrodynamically lubricated finite line contacts
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2019 (English)In: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 141, no 3, article id 031502Article in journal (Refereed) Published
Abstract [en]

In order to adapt to increasingly stringent CO2 regulations, the automotive industry must develop and evaluate low cost, low emission solutions in the powertrain technology. This often implies increased power density and the use of low viscosity oils, leading to additional challenges related to the durability of various machine elements. Therefore, an increased understanding of lubricated contacts becomes important where oil viscosity-pressure and compressibility-pressure behaviour have been shown to influence the film thickness and pressure distribution in EHL contacts, further influencing the durability. In this work, a finite line EHL contact is analysed with focus on the oil compressibility- and viscositypressure response, comparing two oils with relatively different behaviour and its influence on subsurface stress concentrations in the contacting bodies. Results indicate that increased pressure gradients and pressure spikes, and therefore increased localized stress concentrations, can be expected for stiffer, less compressible oils, which under transient loading conditions not only affect the outlet but also the edges of the roller

Place, publisher, year, edition, pages
ASME Press, 2019
Keywords
Elastohydrodynamic lubrication; Finite line contacts; Sub-surface stress; Transient loading
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-71551 (URN)10.1115/1.4041733 (DOI)
Funder
Swedish Energy Agency, 41215-1
Note

Validerad;2018;Nivå 2;2018-12-07 (johcin)

Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-12-07Bibliographically 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
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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
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
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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
Dittes, N., Pettersson, A., Marklund, P., Lang, D. & Lugt, P. M. (2018). Dielectric Thermoscopy Characterization of Water Contaminated Grease. Tribology Transactions, 74(3), 60-73
Open this publication in new window or tab >>Dielectric Thermoscopy Characterization of Water Contaminated Grease
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2018 (English)In: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 74, no 3, p. 60-73Article in journal (Refereed) Published
Abstract [en]

The temperature dependence on the dielectric properties of water-contaminated grease is investigated in this article. The purpose of this investigation was to identify the dielectric properties that could be measured to differentiate varying levels of water contamination in calcium sulfonate complex (CaS-X) grease with three different test cells with the purpose of eventually developing a grease condition sensor. Measuring the change in dielectric constant over a small temperature change yielded useful estimations of water content and amount of grease where the added water content ranged from 0.22% to about 5.5%. Additionally, other parameters such as incomplete fill/coverage of the sensors were investigated as a prestudy. The results from this set of experiments show that the measurement has potential to be developed into a condition monitoring sensor in the future.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-65054 (URN)10.1080/10402004.2017.1333664 (DOI)000444573200001 ()2-s2.0-85045005667 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-04-16 (andbra)

Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2018-10-09Bibliographically approved
Hultqvist, T., Shirzadegan, M., Vrček, A., Baubet, Y., Prakash, B., Marklund, P. & Larsson, R. (2018). Elastohydrodynamic lubrication for the finite line contact under transient loading conditions. Tribology International, 127, 489-499
Open this publication in new window or tab >>Elastohydrodynamic lubrication for the finite line contact under transient loading conditions
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2018 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 127, p. 489-499Article in journal (Refereed) Published
Abstract [en]

Research related to elastohydrodynamic lubrication (EHL) has led to improved performance and durability of machine elements where non-conformal contact geometries interact. Only a relatively small portion of the EHL literature has, however, dealt with the lubricating performance of finite line contacts under non-steady conditions, commonly found in many practical applications. The purpose of this work has thus been to further understand the behaviour of finite line EHL contacts under transient conditions by studying a finite length roller subjected to a time varying load using a full-system finite element approach. The transient load was shown to initiate oscillations in the system, governed by waves of lubricant moving through the contact, affecting both pressure and film thickness throughout the contact.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Elastohydrodynamic lubrication, Finite line contacts, Transient loading, Finite elements
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-70211 (URN)10.1016/j.triboint.2018.06.035 (DOI)000442334100048 ()2-s2.0-85049452630 (Scopus ID)
Funder
Swedish Energy Agency, 41215-1
Note

Validerad;2018;Nivå 2;2018-08-06 (andbra)

Available from: 2018-08-06 Created: 2018-08-06 Last updated: 2018-09-10Bibliographically approved
Dittes, N., Pettersson, A., Sjödahl, M., Casselgren, J., Marklund, P. & Lugt, P. M. (2018). Optical Attenuation Characterization of Water Contaminated Lubricating Grease. Tribology Transactions, 61(4), 726-732
Open this publication in new window or tab >>Optical Attenuation Characterization of Water Contaminated Lubricating Grease
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2018 (English)In: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 61, no 4, p. 726-732Article in journal (Refereed) Published
Abstract [en]

Water-contaminated grease samples are investigated with attenuation spectra in the visible and near-infrared (NIR) regions in this article. The purpose of this investigation was to identify a model with optical attenuation spectra such that the water content of grease samples could be characterized with a simple measurement setup using common methodology from the field of instrumental chemistry. The ratio between two chosen wavelengths of light appears to approximate the water content of grease samples with an acceptable coefficient of determination using a methodology to show what can potentially be done to develop condition monitoring tools. To illustrate the outlined method, a prestudy of grease aging and oxidation levels is also investigated to show that other variables do not significantly change the measurement.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Applied Mechanics
Research subject
Machine Elements; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-67205 (URN)10.1080/10402004.2017.1404175 (DOI)000438157400015 ()2-s2.0-85044094152 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-08-09 (rokbeg)

Available from: 2018-01-09 Created: 2018-01-09 Last updated: 2018-12-14Bibliographically approved
Söderfjäll, M., Larsson, R., Marklund, P. & Almqvist, A. (2018). Texture-induced effects causing reduction of friction in mixed lubrication for twin land oil control rings. Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, 232(2), 166-178
Open this publication in new window or tab >>Texture-induced effects causing reduction of friction in mixed lubrication for twin land oil control rings
2018 (English)In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 232, no 2, p. 166-178Article in journal (Refereed) Published
Abstract [en]

Piston rings are responsible for a major part of the frictional losses in a heavy-duty diesel engine. Such losses can be reduced by applying texture, such as dimples, on the cylinder liner surface. This paper investigates the effect of such texture on the friction between a land of the oil control ring and a textured cylinder liner via numerical simulation. A simulation model considering inertia and mixed lubrication together with a mass-conserving cavitation model is developed. The model is used to determine the dimple parameters that yield the lowest amount of friction for a specific oil control ring of a heavy-duty diesel engine

Place, publisher, year, edition, pages
Sage Publications, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-63889 (URN)10.1177/1350650117709152 (DOI)000424781600008 ()2-s2.0-85042864633 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-02-12 (svasva)

Available from: 2017-06-12 Created: 2017-06-12 Last updated: 2018-03-14Bibliographically approved
Schnabel, S., Golling, S., Marklund, P. & Larsson, R. (2017). Absolute Measurement of Elastic Waves Excited by Hertzian Contacts in Boundary Restricted Systems. Tribology letters, 65(1), Article ID 7.
Open this publication in new window or tab >>Absolute Measurement of Elastic Waves Excited by Hertzian Contacts in Boundary Restricted Systems
2017 (English)In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 65, no 1, article id 7Article in journal (Refereed) Published
Abstract [en]

In most applied monitoring investigations using acoustic emission, measurements are carried out relatively, even though that limits the use of the extracted information. The authors believe acoustic emission monitoring can be improved by instead using absolute measurements. However, knowledge about absolute measurement in boundary restricted systems is limited. This article evaluates a method for absolute calibration of acoustic emission transducers and evaluates its performance in a boundary restricted system. Absolute measured signals of Hertzian contact excited elastic waves in boundary restricted systems were studied with respect to contact time and excitation energy. Good agreement is shown between measured and calculated signals. For contact times short enough to avoid interaction between elastic waves and initiating forces, the signals contain both resonances and zero frequencies, whereas for longer contact times the signals exclusively contained resonances. For both cases, a Green’s function model and measured signals showed good agreement.

Place, publisher, year, edition, pages
Springer, 2017
Keywords
Hertz contact, Elastic waves, Acoustic emission, Green’s function, Boundary restricted system, Condition monitoring
National Category
Applied Mechanics Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-60934 (URN)10.1007/s11249-016-0790-8 (DOI)000397039300007 ()2-s2.0-85000359790 (Scopus ID)
Funder
VINNOVA, 198503
Note

Validerad; 2017; Nivå 2; 2016-12-19 (andbra)

Available from: 2016-12-06 Created: 2016-12-06 Last updated: 2018-12-14Bibliographically approved
Strömbergsson, D., Marklund, P., Edin, E. & Zeman, F. (2017). Acoustic emission monitoring of a mechanochemical surface finishing process. Tribology International, 112, 129-136
Open this publication in new window or tab >>Acoustic emission monitoring of a mechanochemical surface finishing process
2017 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 112, p. 129-136Article in journal (Refereed) Published
Abstract [en]

Acoustic emission monitoring of cutting machining operations is an established researched area, though monitoring non-removal finishing processes is less studied.

This work presents an initial investigation on Acoustic emissions potential of an mechanochemical superfinishing process. Conclusions are drawn from the monitoring signal regarding the resulting surface friction characteristics, composition and possible runnability issues.

Monitoring data was collected from tests performed at Applied Nano Surfaces' testing laboratory. Test series with varying parameters enabled a correlation analysis between the monitoring data, surface friction characteristics and tribofilm formation. Increasing tool wear tests were monitored to find early runnability warning.

Results shows Acoustic emissions indication potential when the finishing process has achieved the intended friction reduction, tribofilm deposition as well as runnability issues identification.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-62937 (URN)10.1016/j.triboint.2017.03.031 (DOI)000401217100015 ()2-s2.0-85017199001 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-04-18 (rokbeg)

Available from: 2017-04-07 Created: 2017-04-07 Last updated: 2018-09-13Bibliographically approved
Martin del Campo Barraza, S., Schnabel, S., Sandin, F. & Marklund, P. (2017). Detection of particle contaminants in rolling element bearings with unsupervised acoustic emission feature learning. Tribology International
Open this publication in new window or tab >>Detection of particle contaminants in rolling element bearings with unsupervised acoustic emission feature learning
2017 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464Article in journal (Other academic) In press
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Machine Elements; Industrial Electronics
Identifiers
urn:nbn:se:ltu:diva-63112 (URN)
Available from: 2017-04-21 Created: 2017-04-21 Last updated: 2018-12-12
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-3157-4632

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