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Effect of humidity on the tribological behaviour and airborne particle emissions of railway brake block materials
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).ORCID iD: 0000-0001-7560-6232
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).ORCID iD: 0000-0003-2489-0688
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. Vol. 118, p. 360-367
Keyword [en]
Airborne particles, Brake block, Humidity, Pin-on-disc
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
URN: urn:nbn:se:kth:diva-218916DOI: 10.1016/j.triboint.2017.10.011ISI: 000423004700035Scopus ID: 2-s2.0-85032008346OAI: oai:DiVA.org:kth-218916DiVA, id: diva2:1161858
Note

QC 20171201

Available from: 2017-12-01 Created: 2017-12-01 Last updated: 2018-04-03Bibliographically approved
In thesis
1. Railway Open System Tribology
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
Keyword
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

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Lyu, YezheOlofsson, Ulf

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