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Lyu, Y., Bergseth, E., Tu, M. & Olofsson, U. (2018). Effect of humidity on the tribological behaviour and airborne particle emissions of railway brake block materials. Tribology International, 118, 360-367
Open this publication in new window or tab >>Effect of humidity on the tribological behaviour and airborne particle emissions of railway brake block materials
2018 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 118, p. 360-367Article in journal (Refereed) Published
Abstract [en]

A pin-on-disc tribometer placed in a one-way ventilated chamber was used to investigate the effect of relative humidity on the tribology and airborne particle emission of three commercial railway brake block materials (grey cast iron, organic composite, and sintered). Cast iron showed the highest friction coefficient, particle emission and wear loss and organic composite exhibited the lowest. The generation of oxide layers on the worn cast iron surface resulted in a decrease in friction, particle emission and wear. Moisture adsorption by the organic composite leads to decreased friction coefficient and particle emission with increasing humidity. Relative humidity does not affect the friction coefficient of the sintered brake block, whose particle emission and wear loss significantly decline with increasing relative humidity.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Airborne particles, Brake block, Humidity, Pin-on-disc
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-218916 (URN)10.1016/j.triboint.2017.10.011 (DOI)000423004700035 ()2-s2.0-85032008346 (Scopus ID)
Note

QC 20171201

Available from: 2017-12-01 Created: 2017-12-01 Last updated: 2018-04-03Bibliographically approved
Cha, Y., Tu, M., Bergstedt, E., Carlsson, P., Lyu, Y., Olofsson, U., . . . Norman, M. (2018). Ombordmätningar av luftburna partiklar i X60 samt på citybanans plattformar. Kungliga Tekniska högskolan
Open this publication in new window or tab >>Ombordmätningar av luftburna partiklar i X60 samt på citybanans plattformar
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2018 (Swedish)Report (Other (popular science, discussion, etc.))
Place, publisher, year, edition, pages
Kungliga Tekniska högskolan, 2018
Series
TRITA-MMK, ISSN 1400-1179 ; 2018:02
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
The KTH Railway Group - Tribology
Identifiers
urn:nbn:se:kth:diva-221674 (URN)
Note

QC 20180122

Available from: 2018-01-19 Created: 2018-01-19 Last updated: 2018-03-13Bibliographically approved
Olofsson, U. & Lyu, Y. (2018). Open System Tribology in the Wheel-Rail Contact-A Literature Review. Applied Mechanics Review, 69(6), Article ID 060803.
Open this publication in new window or tab >>Open System Tribology in the Wheel-Rail Contact-A Literature Review
2018 (English)In: Applied Mechanics Review, ISSN 0003-6900, E-ISSN 1088-8535, Vol. 69, no 6, article id 060803Article, review/survey (Refereed) Published
Abstract [en]

The tiny contact zone (approximately 1 cm2) where steel wheel meets steel rail is fundamental to rail transport. This work is a comprehensive presentation of recent research in wheel-rail contact tribology. It stresses that, unlike gears or rolling bearings which are sealed contacts with reduced exposure to the surrounding environment, a wheel-rail contact is an open system that is exposed to dirt and particles as well as to applied and natural lubrication (the latter category includes rain, dew, and biological materials such as leaves). As an open system contact, it also radiates sound and airborne wear particles. These characteristics of an open system underscore the need for special studies of open system tribology. Areas requiring study include airborne particle emissions and the environmental effects of applied lubrication and friction modification. Given that adhesion, wear, and sound and particle emission are closely related in an open system, these should be studied together rather than independently.

Place, publisher, year, edition, pages
ASME Press, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-225341 (URN)10.1115/1.4038229 (DOI)000417654900004 ()2-s2.0-85034063407 (Scopus ID)
Funder
Swedish Transport Administration
Note

QC 20180403

Available from: 2018-04-03 Created: 2018-04-03 Last updated: 2018-04-03Bibliographically approved
Lyu, Y. (2018). Railway Open System Tribology. (Doctoral dissertation). Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>Railway Open System Tribology
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Tribology in the railway system is of increasing interest in the new railway era due to the demand for higher speed and load capacity. Since railway vehicles operate in an open environment, their performance depends greatly on temperature, humidity and natural and artificial contaminants. Meanwhile, the “feedback” of railway vehicles to the surroundings, such as noise and airborne particles, is of great importance to the human health and the environment. Therefore, this thesis aims to investigate the strong interaction between railway tribology and the open environment. The effects of temperatures from -35 °C to 20 °C, relative humidity from 40% to 85%, natural contaminants such as ice particles on friction, wear, noise and airborne particle emissions at the wheel–rail and wheel–block brake contacts have been investigated in both lab- and full-scale contexts.

Papers A and B investigated the effect of temperature, humidity and ice particles on the friction and wear at unoxidized and oxidized wheel–rail contacts. The results indicate that increasing humidity reduces the wear at unoxidized contacts. A decrease in temperature tends to intensify the wear until an ice layer has condensed on the wheel and rail surfaces at -25 °C. Ice particles encourage the generation of oxide flakes at the contacting path, largely inhibiting the wear process.

Paper C, which was a lab-scale test, studied the friction, wear and noise generation from pre-oxidized wheel–rail contact with varied surface features. Major results include that the wear regime transition from mild wear to severe wear is always accompanied by an increase in noise level of 10 dB and a broader bandwidth of noise.

Paper D was a validation of the major findings of paper C in a full-scale test, which also saw an increase in noise level as well as a broader bandwidth when the wheel–rail contact transformed from mild to severe wear.

Paper E studied the effect of humidity on the friction, wear and airborne particle emissions of three railway brake-block materials. The results show that cast iron generated the highest friction coefficient, wear and particle emission, and organic composite the lowest levels.

Paper F conducted a thorough literature review on the open system tribology at the wheel–rail contact. Commonly seen parameters such as temperature, humidity and natural and artificial contaminants on friction, wear, noise and particle emissions were investigated.

Abstract [sv]

Järnvägsfordonen arbetar i en öppen miljö, vars prestanda och livslängd i form av friktion och nötning beror på temperatur, luftfuktighet samt naturliga och konstgjorda föroreningar. Samtidigt är återkopplingen, som järnvägsfordon ger till omgivningen i form av buller och luftburna partiklar, av stor betydelse för människors hälsa. Därför är målsättningen med denna avhandling att undersöka den starka samverkan som finns mellan järnvägsfordon och den öppna miljön.

Effekten av, temperaturer från -35 °C till 20 °C, relativ fuktighet från 40 % till 85 % och naturliga föroreningar som snö, på friktion, slitage, buller och luftburna partikelutsläpp vid hjulräls- och hjulblockbromskontakter har undersökts, både i laboratorier och i full skala.

Manuskript A och B undersökte effekten av temperatur, luftfuktighet och snö på friktionen och nötning vid oxiderade och icke-oxiderade hjulrälskontakter. Resultaten visar att en ökad luftfuktighet, minskar nötningen vid icke-oxiderade kontakter. Minskning av temperaturen tenderar att intensifiera nötningen, tills is kondenseras på hjul- och rälsytorna vid -25 °C. Iskristallerna, ökar hastigheten på genereringen av oxidflingor i kontakten, och förhindrar i stor utsträckning nötningsprocessen.

Manuskript C, som är ett laboratorieprov, studerade friktionen, nötningen och ljudgenerering från föroxiderade hjulrälskontakter med varierande yttopografi. Viktiga resultat, är att övergången, från mild nötning till svår nötning, alltid åtföljs av en ökad ljudnivå och en ökning av ljudets bandbredd.

Manuskript D är en fullskalevalidering av huvudresultatet från Manuskript C, vilket också uppvisade en ökning av ljudnivån om hjulrälskontakten gick från mild till svår nötning åtföljt av en ökning av ljudets bandbredd.

Manuskript E studerade effekten av luftfuktighet på friktion, nötning och luftburna nötningspartiklar av tre olika blockbromsmaterial. Resultaten visar att gjutjärn genererade den högsta friktionskoefficienten, nötningsnivån och halten av partikelutsläpp. Blockbromsar tillverkade av organisk komposit, uppvisade den lägsta nivån för alla tre uppmätta parametrar.

Manuskript F redovisar en litteraturgenomgång, hur det öppna systemet, påverkar tribologin i hjul-järnvägskontakten. Parametrar som temperatur, fuktighet, naturliga och konstgjorda föroreningar på friktion, slitage, buller och partikelutsläpp diskuterades i detalj.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2018. p. 50
Series
TRITA-ITM-AVL ; 2018:6
Keywords
Wheel; Rail; Brake; Environmental conditions; Tribology; Noise; Particle, Hjul; Räl; Broms; Miljöförhållanden; Tribologi; Ljud; Partiklar
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Design
Identifiers
urn:nbn:se:kth:diva-225339 (URN)978-91-7729-710-9 (ISBN)
Public defence
2018-04-27, Gladan, Brinellvägen 85, Stockholm, 11:04 (English)
Supervisors
Available from: 2018-04-03 Created: 2018-04-03 Last updated: 2018-05-15Bibliographically approved
Wahlström, J., Matějka, V., Lyu, Y. & Söderberg, A. (2017). Contact pressure and sliding velocity maps of the friction, wear and emission from a low-metallic/cast-iron disc brake contact pair. Tribology in Industry, 39(4), 460-470
Open this publication in new window or tab >>Contact pressure and sliding velocity maps of the friction, wear and emission from a low-metallic/cast-iron disc brake contact pair
2017 (English)In: Tribology in Industry, ISSN 0354-8996, Vol. 39, no 4, p. 460-470Article in journal (Refereed) Published
Abstract [en]

Particulate matter with an aerodynamic diameter less than 10 µm (PM10) from car disc brakes contribute up to 50% of the total non-exhaust emissions from road transport in the EU. These emissions come from the wear of the pad and rotor contact surfaces. Yet few studies have reported contact pressures and offered sliding speed maps of the friction, wear, and particle emission performance of disc brake materials at a material level. Such maps are crucial to understanding material behaviour at different loads and can be used as input data to numerical simulations. A low-metallic pad and grey cast-iron rotor contact pair commonly used today in passenger car disc brakes was studied using a pin-on-disc tribometer at twelve contact pressure and sliding speed combinations. Maps of the coefficient of friction, specific wear rate, particle number, and mass rate are presented and discussed.

Place, publisher, year, edition, pages
Faculty of Engineering, University of Kragujevac, 2017
Keywords
Disc brake, Emissions, Friction, Maps, Pin-on-disc, Wear
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-223091 (URN)10.24874/ti.2017.39.04.05 (DOI)2-s2.0-85038439180 (Scopus ID)
Note

QC 20180214

Available from: 2018-02-14 Created: 2018-02-14 Last updated: 2018-02-14Bibliographically approved
Silvergren, S., Olofsson, U., Andersson, M., Lyu, Y., Norman, M., Sanchez, G. G., . . . Tu, M. (2017). Ombordmätningar av partiklar och koldioxid i X60B förarhytter. KTH Royal Institute of Technology
Open this publication in new window or tab >>Ombordmätningar av partiklar och koldioxid i X60B förarhytter
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2017 (Swedish)Report (Other (popular science, discussion, etc.))
Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2017. p. 24
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-222151 (URN)
Note

QC 20180205

Available from: 2018-02-01 Created: 2018-02-01 Last updated: 2018-02-05Bibliographically approved
Lyu, Y., Wahlström, J., Matějka, V. & Söderberg, A. (2017). Ranking of conventional and novel disc brake materials with respect to airborne particle emissions. In: Eurobrake 2017: . Paper presented at Eurobrake 2017.
Open this publication in new window or tab >>Ranking of conventional and novel disc brake materials with respect to airborne particle emissions
2017 (English)In: Eurobrake 2017, 2017Conference paper, Published paper (Refereed)
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Design
Identifiers
urn:nbn:se:kth:diva-223387 (URN)
Conference
Eurobrake 2017
Note

QC 20180226

Available from: 2018-02-20 Created: 2018-02-20 Last updated: 2018-02-26Bibliographically approved
Höjer, M., Bergseth, E., Olofsson, U., Nilsson, R. & Lyu, Y. (2016). A noise related track maintenance tool for severe wear detection of wheel-rail contact. Civil-Comp Proceedings, 110
Open this publication in new window or tab >>A noise related track maintenance tool for severe wear detection of wheel-rail contact
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2016 (English)In: Civil-Comp Proceedings, ISSN 1759-3433, Vol. 110Article in journal (Refereed) Published
Abstract [en]

An on-board measurement system has been developed that in real time identifies the probability for occurrence and also the exact location of severe wear in the wheelrail contact. Noise generated by the wheel-rail contact is a troublesome side effect both when railway vehicles negotiate curves and run on straight tracks. The concept behind this project is to use this noise as an indicator of the transition from the mild wear regime to the severe/catastrophic wear regime that implies high maintenance cost. At first tribometers were used in a laboratory study to investigate the relationships between wear and the emitted noise. Wear transitions from mild to severe wear were always accompanied by an increase in sound pressure of about 10 dB. The transitions also changed the sound pressure amplitude distribution from a narrow banded to a broader banded distribution. Secondly a full scale test in a small radius curve in a depot was carried out using a metro train, type C20. In agreement with the laboratory tests, the same kind of transfer from mild to severe wear was identified on the full scale tests in the depot. In addition, the sound pressure changed significantly, both in amplitude and in distribution, when transferring from mild to severe wear. By comparing the noise from the inner wheel-rail contact to noise from the outer wheel-rail contact a wear detection parameter for the outer wheel-rail contact is suggested. The third part of this project involves validation of the maintenance tool by operating the instrumented train in normal metro traffic, while at the same time collecting wear particles and making replicate casts of the rail at critical locations in the metro. Further comparison with weather data and a maintenance log has also been performed. © Civil-Comp Press, 2016.

Keywords
Maintenance, Noise, Wear, Wheel-rail contact, Acoustic noise, Firing (of materials), Wear of materials, Wheels, Critical location, Full scale tests, Laboratory studies, Maintenance tools, On-board measurements, Track maintenance, Wheel-rail contacts, Vehicle wheels
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-186741 (URN)2-s2.0-84964334415 (Scopus ID)
Note

QC 20160527

Available from: 2016-05-27 Created: 2016-05-13 Last updated: 2017-11-30Bibliographically approved
Lyu, Y., Sun, Y. & Yang, Y. (2016). Non-Vacuum Sintering Process of WC/W2C Reinforced Ni-Based Coating on Steel. Metals and Materials International, 22(2), 311-318
Open this publication in new window or tab >>Non-Vacuum Sintering Process of WC/W2C Reinforced Ni-Based Coating on Steel
2016 (English)In: Metals and Materials International, ISSN 1598-9623, E-ISSN 2005-4149, Vol. 22, no 2, p. 311-318Article in journal (Refereed) Published
Abstract [en]

Ni-based composite coatings containing varied contents of tungsten carbides on low carbon steel were fabricated. Effects of sintering temperature and tungsten carbides contents on the surface, interface, microstructure and wear resistance of the coatings were investigated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Vickers microhardness tester, bulk hardness tester and pin-on-disc tribometer. The results indicated that with appropriate sintering temperature (1230 degrees C), smooth coating surfaces can be achieved. Favorable interfaces about 200 mu m can be got that both the chemical composition and property of the interfacial region showed gradual transitions from the substrates to the coatings. Microstructure of the coatings consists of tungsten carbides and M7C3/M23C6 in the matrix. With excessive sintering temperature, tungsten carbides tend to dissolve. Ni-based coatings containing tungsten carbides showed much higher level of bulk hardness and wear resistance than ISO Fe360A and ASTM 1566 steels. With increasing contents of tungsten carbides from 25% to 40%, bulk hardness of Ni-based coatings gradually increased. Ni-based coating with 35% tungsten carbides performed the best wear resistance.

Place, publisher, year, edition, pages
KOREAN INST METALS MATERIALS, 2016
Keywords
coating, sintering, scanning electron microscopy (SEM), X-ray diffraction, wear
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:kth:diva-184546 (URN)10.1007/s12540-016-5462-6 (DOI)000371651300020 ()2-s2.0-84961191244 (Scopus ID)
Note

QC 20160406

Available from: 2016-04-06 Created: 2016-04-01 Last updated: 2017-11-30Bibliographically approved
Lyu, Y., Bergseth, E. & Olofsson, U. (2016). The effect of Subzero temperature and snow on the tribology of wheel-rail contact. Civil-Comp Proceedings, 110
Open this publication in new window or tab >>The effect of Subzero temperature and snow on the tribology of wheel-rail contact
2016 (English)In: Civil-Comp Proceedings, ISSN 1759-3433, Vol. 110Article in journal (Refereed) Published
Abstract [en]

The wheel-rail system operates in an open environment where the weather condition varies constantly. In this laboratory study, an investigation using a pin-on-disc tribometer placed in a temperature-controlled room was conducted to examine the effect of subzero temperature and snow on friction and wear at the wheel-rail contact. In temperature range from 3 to-15 °C (without snow) friction and wear were dominated by low temperature brittleness, which led to an increase in friction and wear. When temperature decreased down to-25 °C, an ice layer condensed on the pin and disc surfaces, which then melted during sliding and acted as a lubricant, leading to the sharp decrease of friction and wear. When snow crystals were added into the contact they melted into water droplets during sliding because of pressure melting and reduced the friction and wear following the boundary lubrication mechanism. With increasing temperature from-25 to 3 °C, friction performed monotonously decreasing because of the increasing thickness of the water layer. A large area of oxide flakes generated on the worn surfaces also significantly protected the contacting wheels and rails from severe wear. © Civil-Comp Press, 2016.

Keywords
Brittleness, Friction, Oxides, Pearlite, Pin-on-disc, Precipitation, Saturation vapour pressure, Snow, Steel, Temperature, Wear, Wheel-rail contact, Fracture mechanics, Plasticity, Precipitation (chemical), Tribology, Vehicle wheels, Wear of materials, Wheels, Boundary lubrications, Increasing temperatures, Monotonously decreasing, Pin on disc, Pin on disc tribometer, Saturation vapour pressures, Sub-zero temperatures, Wheel-rail contacts
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-186771 (URN)2-s2.0-84964381125 (Scopus ID)
Note

QC 20160530

Available from: 2016-05-30 Created: 2016-05-13 Last updated: 2017-11-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7560-6232

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