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Schnabel, Stephan
Publications (10 of 12) Show all publications
Martin del Campo Barraza, S., Schnabel, S., Sandin, F. & Marklund, P. (2019). Detection of particle contaminants in rolling element bearings with unsupervised acoustic emission feature learning. Tribology International, 132, 30-38
Open this publication in new window or tab >>Detection of particle contaminants in rolling element bearings with unsupervised acoustic emission feature learning
2019 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 132, p. 30-38Article in journal (Refereed) Published
Abstract [en]

The detection of contaminants in the lubricant of rolling element bearings using acoustic emission signals is a challenging problem, in particular at high rotational speeds. This problem calls for new analysis methods beyond the conventional amplitude- and frequency-based methods. Feature learning is successfully used in the machine learning field to characterize complex signals. Here we use an unsupervised feature learning approach to distinguish acoustic emission signals. We investigate the repetition rates of features identified with shift-invariant dictionary learning and find that the signature of contaminated lubricant is significantly stronger than the effect on conventional condition indicators like the RMS and the enveloped RMS at rotational speeds above 300 rpm and up to 3000 rpm.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Acoustic emission, Contamination, Dictionary learning, Unsupervised feature learning
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)10.1016/j.triboint.2018.12.007 (DOI)000456758700004 ()2-s2.0-85058395512 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-01-03 (svasva)

Available from: 2017-04-21 Created: 2017-04-21 Last updated: 2019-05-14Bibliographically 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
Schnabel, S., Marklund, P. & Larsson, R. (2017). Elastic Waves of a Single Elasto-Hydrodynamically Lubricated Contact. Tribology letters, 65(1), Article ID 5.
Open this publication in new window or tab >>Elastic Waves of a Single Elasto-Hydrodynamically Lubricated Contact
2017 (English)In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 65, no 1, article id 5Article in journal (Refereed) Published
Abstract [en]

Elastic waves are widely used for condition monitoring of rolling element bearings through vibration or acoustic emission measurements . While vibration signals are understood to a high degree due to many scientific investigations as well as a long history of usage in the field, acoustic emission signals of rolling element bearings are poorly understood. Therefore, this investigation presents simulation studies and measurements of a single elasto-hydrodynamically lubricated (EHL) contact. In this investigation the EHL contact is a ball bouncing on a lubricated plate. The simulation based on Green’s function and the measurements based on a accelerometer to some extent agree. A shift of zero frequencies towards higher frequencies when compared to Hertzian reference measurements was determined for an infinite plate setup. Taking boundary restrictions into account, elastic waves of a Hertzian contact and an EHL contact only differ by a damping of higher resonances which is most likely caused by the EHL film.

Place, publisher, year, edition, pages
Springer, 2017
Keywords
EHL contact, EHL, Hertz contact, Elastic waves, Acoustic emission, Green’s function, Ball impact, Bouncing ball
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Fluid Mechanics and Acoustics Applied Mechanics
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-60962 (URN)10.1007/s11249-016-0785-5 (DOI)000397039300005 ()2-s2.0-85000443041 (Scopus ID)
Funder
VINNOVA, 198503
Note

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

Available from: 2016-12-07 Created: 2016-12-07 Last updated: 2018-12-14Bibliographically approved
Schnabel, S., Marklund, P., Larsson, R. & Golling, S. (2017). The Detection of Plastic Deformation in Rolling Element Bearings by Acoustic Emission. Tribology International, 110, 209-215
Open this publication in new window or tab >>The Detection of Plastic Deformation in Rolling Element Bearings by Acoustic Emission
2017 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 110, p. 209-215Article in journal (Refereed) Published
Abstract [en]

The detection of plastic deformation caused by particle contamination in rolling element bearings using acoustic emission is reliable at low speeds as shown in several studies. However, there are no studies at greater speeds of the detection of plastic deformation by acoustic emission in rolling element bearings. The acoustic emission signals of rolling element bearings have, however, been shown to be dominated by transient force signals which are elastic waves caused by transient forces acting at the raceway surface. The results of the test showed a dominance of transient force signals at elevated speeds, which masks signals caused by plastic deformation and prohibits the detection of particle contamination, while at low rotational speed plastic deformation is detected by acoustic emission.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Applied Mechanics
Research subject
Machine Elements; Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-62088 (URN)10.1016/j.triboint.2017.02.021 (DOI)000398871700023 ()2-s2.0-85013782176 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-03-09 (andbra)

Available from: 2017-02-20 Created: 2017-02-20 Last updated: 2018-09-13Bibliographically approved
Schnabel, S., Golling, S., Marklund, P. & Larsson, R. (2017). The influence of contact time and event frequency on acoustic emission signals. Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, 231(10), 1341-1349
Open this publication in new window or tab >>The influence of contact time and event frequency on acoustic emission signals
2017 (English)In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 231, no 10, p. 1341-1349Article in journal (Refereed) Published
Abstract [en]

Studies of acoustic emissions (AE) of rotating machine elements is often performed under a constant speed. There are few investigations on speed and contact time dependency of acoustic emission signals, even though some investigations have reported difficulties at elevated rotational speeds. Simplified experiments are, therefore, presented in this article to increase the understanding of the time dependency of acoustic emission signals. Hertzian impacts and tensile tests are used to study contact time, the time duration of an event and offset time, the time between events and accordingly the event frequency. The results of these model experiments indicate an indirect quadratic proportionality of acoustic emission amplitudes and contact time (umax∝1/(tc2)">u max ∝1/(t 2 c ) umax∝1/(tc2) ), as well as a proportional relationship between the root mean square and event frequency (RMS∝fevent∝1/toffset">RMS∝f event ∝1/t offset  RMS∝fevent∝1/toffset ). The relationship between contact time and the root mean square of acoustic emission signals is strongly dependent on the damping of the system

Place, publisher, year, edition, pages
Sage Publications, 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-62114 (URN)10.1177/1350650117693176 (DOI)000412739600008 ()2-s2.0-85031315259 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-10-16 (svasva)

Available from: 2017-02-22 Created: 2017-02-22 Last updated: 2018-03-09Bibliographically approved
Martin-del-Campo, S., Sandin, F., Schnabel, S., Marklund, P. & Delsing, J. (2016). Exploratory Analysis of Acoustic Emissions in Steel using Dictionary Learning. In: IEEE Ultrasonics Symposium 2016, Tours France, September 18-21, 2016: . Paper presented at IEEE Ultrasonics Symposium 2016, Tours France, September 18-21, 2016. Piscataway, NJ: IEEE conference proceedings, Article ID 7728825.
Open this publication in new window or tab >>Exploratory Analysis of Acoustic Emissions in Steel using Dictionary Learning
Show others...
2016 (English)In: IEEE Ultrasonics Symposium 2016, Tours France, September 18-21, 2016, Piscataway, NJ: IEEE conference proceedings, 2016, article id 7728825Conference paper, Published paper (Refereed)
Abstract [en]

Analysis of acoustic emissions (AE) from steel deformation is a challenging condition monitoring problem due to the high frequencies and data rates involved, and the difficulty to separate signals from noise. The problem to characterize and identify different AE sources calls for methods that goes beyond conventional time and frequency domain analysis. Feature learning is common in the field of machine learning and is successfully used to approximate and classify other kinds of complex signals. Former studies show that AE classification results depend on the choice of predefined features that are extracted from the raw AE signal, but little is known about feature learning in this context. Here we use dictionary learning and sparse coding to optimize a set of shift-invariant features to the AE signal measured in a steel tensile strength test. The specimen undergoes elastic and plastic deformation and eventually cracks. We investigate the learned features and their repetition rates and use principal component analysis (PCA) to illustrate that the resulting sparse AE code is useful for classification of the three strain stages, without reference to the signal amplitude. Therefore, feature learning is a potentially useful approach to the AE analysis problem, which also opens up for further studies of automated methods for anomaly detection in AE.

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE conference proceedings, 2016
Series
Proceedings - IEEE Ultrasonics Symposium, ISSN 1948-5719
Keywords
Dictionary Learning, Acoustic Emission
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Industrial Electronics; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-59776 (URN)10.1109/ULTSYM.2016.7728825 (DOI)000387497400452 ()2-s2.0-84996567218 (Scopus ID)978-1-4673-9897-8 (ISBN)978-1-4673-9898-5 (ISBN)
Conference
IEEE Ultrasonics Symposium 2016, Tours France, September 18-21, 2016
Available from: 2016-10-16 Created: 2016-10-16 Last updated: 2019-05-14Bibliographically approved
Schnabel, S. (2016). High Frequency Elastic Wave Emission Caused by a Single Elastohydrodynamically Lubricated Contact: Fundamental sources and Principles. (Doctoral dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>High Frequency Elastic Wave Emission Caused by a Single Elastohydrodynamically Lubricated Contact: Fundamental sources and Principles
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Elastohydrodynamically lubricated (EHL) contacts are fundamental for severalrotating machine elements. For example gears, rolling element bearingsand lubricated chain drives work due to the principle of EHL. All of these machineelements require maintenance and, as condition based maintenance hasincreased in industry, the need for monitoring techniques has also increased. Inorder to avoid incorrect condition indications, since the 60’s researchers haveimproved signal processing of existing monitoring tools and developed newtechniques as a complement to these existing tools. In the past two decadesacoustic emission has been identified as a new complementary tool for monitoringof rolling element bearings and investigated intensively by several researchgroups. However, most of the investigations were carried out at lowrotational speeds. Furthermore, most of the investigations used simple signalprocessing methods like activation counts (AC) or trend analysis of the rootmean square signal (RMS). One reason for using simple experimental conditionsand signal processing methods is the complexity of a rolling elementbearing itself. A rolling element bearing consists of several EHL contacts andeach contact has different operational conditions (film thickness, slide to rollratio, contact pressure, entrainment speed). The measured signal is the summationof all EHL contacts. This complexity is one reason why the high frequencyemissions of an EHL contact are still not fully understood. Therefore, an investigationof the acoustic emission of a single EHL contact was here carriedout within the framework of a PhD project.In this thesis simplified experiments were used to represent either a single EHLcontact or elements of an EHL contact. Both acoustic emissions of tensile testsand ball impacts on a solid plate were studied and analyzed with respect totheir significance for EHL contacts. For all investigations carried out in thisthesis an absolute calibration method developed by McLaskey and Glaser wasused. This calibration method was validated for boundary restricted systems,where a good agreement for zero frequencies was found, however, unsatisfying agreement was discovered for resonances of a boundary restricted system. Theinvestigation found elastic waves in boundary restricted systems consist of twofundamental types. Zero frequencies will be enhanced for cases were excitationsource and elastic wave are independent, while an interaction of sourceand elastic wave results in a pure resonance problem.Furthermore, the time dependency of acoustic emission signals was investigated.As mentioned previously most existing investigations are carried outat low and constant rotational speed. The dependency of acoustic emissionsignals and speed is reported in literature as well as difficulties with acousticemission measurements at elevated rotational speeds. By using ball impactswith different ball sizes and tensile tests with different displacement speeds thetime dependency was analyzed with respect to excitation time (contact time ofball impact) and event frequency (amount of dislocation movement and planeslip movements in a certain time frame). Thereby an indirect quadratic proportionalitybetween acoustic emission amplitude and contact time was found.This proportional relationship is also valid for RMS signals with short averagingwindows if system damping is low. For event frequency and RMS signalsthe results of the tensile tests suggest a direct proportional relationship.Furthermore, Hertzian and EHL contact impacts were studied and compared.Thereby it was observed that the overall amplitude of the signal increases forEHL contacts in comparison to Hertzian contacts. In addition the third zerofrequency disappears, which is most likely due to cavitation effects. Furthermore,the results show a shift of the first and second zero frequency towardshigher frequencies, which is caused by the localised deformation of EHL contactsas a result of the solidification of the lubricant. This behaviour of zerofrequencies was in line with simulation results. However, the agreement betweensimulation and measurement for the location of zero frequencies and thesignal amplitude was not satisfying. This mismatch was most likely caused bythe assumption of the global contact force acting at a single point, causing aperfect elastic deformation in the simulation. Additionally, for the findings regardingzero frequencies, a change in the excitation of resonances above thefirst zero frequency in boundary restricted systems was also found, comparingHertzian and EHL impacts.Finally, full scale tests on a complete rolling element bearing were carried outduring the PhD project to validate findings of the single contact experiments.Magnetite contaminated rolling element bearings and their acoustic emissionsignals were investigated with respect to the use of sulfur additives, contaminationand rotational speed. These tests were executed at varying speed forsingle measurements and constant speed for continuous measurement recording. The results of the full scale tests showed good agreement with previousresults of the component tests, such as bouncing ball and tensile tests. Transientforces are the main source of signals for well lubricated rolling elementbearings or bearings at high rotational speed, while acoustic emission signalsof contaminated bearings at low rotational speed were dominated by plasticdeformation signals. Furthermore, it was found that sulfur additives reducethe plastic deformation signal by up to 70% in comparison to contaminatedbearings lubricated with plain grease.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2016
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-343 (URN)978-91-7583-686-7 (ISBN)978-91-7583-687-4 (ISBN)
Public defence
2016-10-21, E632, Luleå tekninska universitet, Luleå, 09:00
Opponent
Available from: 2016-09-26 Created: 2016-09-26 Last updated: 2018-01-10Bibliographically approved
Schnabel, S., Marklund, P., Minami, I. & Larsson, R. (2016). Monitoring of Running-in of an EHL contact using Contact Impedance (ed.). Tribology letters, 63(3), Article ID 35.
Open this publication in new window or tab >>Monitoring of Running-in of an EHL contact using Contact Impedance
2016 (English)In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 63, no 3, article id 35Article in journal (Refereed) Published
Abstract [en]

Running-in is an important process for elasto-hydrodynamic lubricated contacts, which affect both service life and operating performance. However, the possibilities of monitoring running-in are still poor. Therefore, the properties of electrical contact impedance as a monitoring tool were studied by using an in-house made ball on disc apparatus. The contact impedance was monitored during run-in experiments with different initial surface roughness of the discs, different slide-to-roll ratios and with pure or additive containing paraffinic oil. The relationship between surface roughness parameters, contact resistance and contact capacitance was investigated. While the contact resistance seems to be affected by the parameter Rz, the contact capacitance seems more dependent on Rq. In addition, the experiments showed that surface active additives do not necessarily need to influence the contact impedance.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-11283 (URN)10.1007/s11249-016-0727-2 (DOI)000382392200006 ()2-s2.0-84980348005 (Scopus ID)a37dc38a-d673-4f61-9b7e-958fa055c66e (Local ID)a37dc38a-d673-4f61-9b7e-958fa055c66e (Archive number)a37dc38a-d673-4f61-9b7e-958fa055c66e (OAI)
Note

Validerad; 2016; Nivå 2; 20160809 (stesch)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Schnabel, S. (2014). Monitoring of wear in elasto- hydrodynamic lubricated contacts: Running-in and failure propagation (ed.). (Licentiate dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Monitoring of wear in elasto- hydrodynamic lubricated contacts: Running-in and failure propagation
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Alternative title[sv]
Övervakning av nötning i elastohydrodynamiska smörjda kontakter : Inkörning och felutveckling
Abstract [en]

Elasto-hydrodynamic lubricated (EHL) contacts can be found in various machine elements or systems, like rolling element bearings, cam followers or gear transmissions. The service life of these elements and systems are depending to some extent on the performance of EHL contacts. Today most tribological contacts are lubricated with the same type of lubricant throughout the entire service life. However operating conditions can change over the components service life and the contacts will therefore require different lubricant properties. In order to expend the service life of the component, the lubrication of the tribological contacts has to be optimized based on the current operating conditions. A future vision is to develop machine elements which can adopt to the actual operating condition, so called triboactive systems. A first step of necessary research in order to develop such systems is presented in this work.In order to enable operation dependent lubrication the mechanism of monitoring techniques and their interaction with different operating conditions have to be investigated. In this work the effect of surface topography, slide to roll ratio and additives on the running-in and the monitoring by contact impedance were studied. Characteristic dependences between the surface parameter Rq and the contact capacitance and between the surface parameter Rz and the contact resistance were found. Further tests with iron oxide (FE3O4) contaminated bearings, monitored by vibration and acoustic emission were carried out. Premature failure due to iron oxide contamination is the most common problem for rolling element bearings operating in mining environment. Thereby the effect of iron oxide contamination on the vibration and acoustic emission monitoring for two different types of greases were investigated. It was found that a simple RMS analysis of the vibration and acoustic emission signals enables the detection of improvements of contaminated contacts by lubrication. Both vibration and acoustic emission from the investigated bearings were reduced by adding extreme pressure additives (EP) to the contaminated contacts.Monitoring of the lubrication condition is necessary to generate information about the current performance of the tribological contact. However, in order to improve the performance of tribological contacts by changes of the lubricant or additives, the effect of such additives on the lubrication condition and the performance of the tribological contact need to be studied more in detail. The presented running-in tests in this work showed that EP additives are only favourable in the very first stage of running-in. The advantage of EP additives for running-in increases with increased surface roughness and increased slide to roll ratio.Another advantage of EP additives was observed during the tests with iron oxide contaminants. The use of EP additives reduced the acoustic emissions of the tribological contact by 70% and reduced the increase of surface roughness of the raceways by as much as 60%. Furthermore the tests indicate a lower wear rate for contaminated EHL contacts lubricated with greases containing EP additives in comparison to plain grease without EP additives, in case of iron oxide contaminated EHL contacts.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2014. p. 94
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-18264 (URN)7a818354-c5a0-45d2-8f34-6069a864a386 (Local ID)978-91-7439-854-0 (ISBN)978-91-7439-855-7 (ISBN)7a818354-c5a0-45d2-8f34-6069a864a386 (Archive number)7a818354-c5a0-45d2-8f34-6069a864a386 (OAI)
Note
Godkänd; 2014; 20131128 (stesch); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Stephan Schnabel Ämne: Maskinelement/Machine Elements Uppsats: Monitoring of Wear in Elasto-Hydrodynamic Lubricated Contacts Running-in and Failure Propagation Examinator: Bitr professor Pär Marklund, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: PhD Lars-Erik Stacke, AB SKF, Tool R&D, Knowledge & Simulation Tools, Göteborg Tid: Fredag den 28 februari 2014 kl 10.00 Plats: E231, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-01-10Bibliographically approved
Schnabel, S., Marklund, P. & Larsson, R. (2014). Study of the short-term effect of Fe3O4 particles in rolling element bearings: Observation of vibration, friction and change of surface topography of contaminated angular contact ball bearings (ed.). Paper presented at . Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, 228(10), 1063-1070
Open this publication in new window or tab >>Study of the short-term effect of Fe3O4 particles in rolling element bearings: Observation of vibration, friction and change of surface topography of contaminated angular contact ball bearings
2014 (English)In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 228, no 10, p. 1063-1070Article in journal (Refereed) Published
Abstract [en]

The harsh environment rolling element bearings are exposed to in iron-mining industries is replicated in a laboratory scale in this work. Bearings (SKF 7204BEP) were tested both with and without magnetite oxide (Fe3O4) contamination. In order to study the interaction between contaminants and extreme pressure additives, the rolling element bearings were lubricated with two different greases: Grease without extreme pressure and grease containing sulphur-based extreme pressure additives. Further, the effect of the contamination–additive interaction on rolling bearing performance and monitoring signals (vibration and acoustic emission) was investigated. The obtained results indicate an advantage of extreme pressure additive in case of the investigated operating conditions. Furthermore, the use of extreme pressure additives decreased wear, surface roughness, vibration and acoustic emission for both test durations of 24 h and 168 h. The decrease of the acoustic emissions and the surface roughness parameter Rq in case of the tests with a duration of 168 h as high as 70% and 60%, respectively using extreme pressure additives in comparison with the plain grease was observed. The major cause for this reduction seems to be the interaction between contaminants and extreme pressure additives.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-12855 (URN)10.1177/1350650114526582 (DOI)000341997000005 ()c00e9ce2-029e-4bae-a0ff-cc1dc8bf3a7a (Local ID)c00e9ce2-029e-4bae-a0ff-cc1dc8bf3a7a (Archive number)c00e9ce2-029e-4bae-a0ff-cc1dc8bf3a7a (OAI)
Note
Validerad; 2014; 20140321 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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