| 1. |
- Bergseth, Ellen, 1979-, et al.
(författare)
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A Wear Detection Parameter for the Wheel–Rail Contact Based on Emitted Noise
- 2019
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Ingår i: Tribology Transactions. - : Informa UK Limited. - 1040-2004 .- 1547-397X. ; 62:3, s. 496-503
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Tidskriftsartikel (refereegranskat)abstract
- This article describes how a wheel–rail wear detection parameter based on noise was developed by running a rapid transit train instrumented with microphones in a depot with a small curve radius. This full-scale test made use of previous knowledge gained from lab-scale tests. The lab- and full-scale tests showed that noise could be used as an indicator of wear transition, when normal wear turns into severe or catastrophic wear. This transition was accompanied by a significant increase in sound pressure and a broader sound pressure amplitude spectrum; that is, a narrow initial amplitude distribution in the normal wear regime and a broader distribution in the severe wear regime. The measured noise from the inner/low and outer/high rails was analyzed in conjunction with the wear from the outer wheel and comparisons were made between cleaned (exposed to severe wear) and lubricated (no wear) rail. Based on those analyses, a wear detection parameter criterion was developed for this specific train. This wear parameter has been implemented in a real-time condition monitoring system so that warnings of the risk for severe wear could be sent to the maintenance department. Validation of the wear parameter and challenges linked to open system conditions are discussed in this article.
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| 2. |
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| 3. |
- Dizdar, Senad, et al.
(författare)
-
Grey Cast Iron Brake Discs Laser Cladded with Nickel-Tungsten Carbide-Friction, Wear and Airborne Wear Particle Emission
- 2020
-
Ingår i: Atmosphere. - Basel : MDPI. - 2073-4433. ; 11:6
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Tidskriftsartikel (refereegranskat)abstract
- Airborne wear particle emission has been investigated in a pin-on-disc tribometer equipped with particle analysis equipment. The pins are cut out from commercial powder metallurgy automotive brake pads as with and without copper content. The discs are cut out from a commercial grey cast iron automotive brake disc as cut out and as in addition to a laser cladded with a powder mix of Ni-self fluxing alloy + 60% spheroidized fused tungsten carbide and then fine-ground. Dry sliding wear testing runs under a contact pressure of 0.6 MPa, sliding velocity of 2 m/s and a total sliding distance of 14,400 m. The test results show both wear and particle emission improvement by using laser cladded discs. The laser cladded discs in comparison to the reference grey cast iron discs do not alter pin wear substantially but achieves halved mass loss and quartered specific wear. Comparing in the same way, the friction coefficient increases from 0.5 to 0.6, and the particle number concentration decreases from over 100 to some 70 (1/cm(3)) and the partition of particles below 7 mu m is approximately halved.
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| 4. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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A Friction, Wear and Emission Tribometer Study of Non-Asbestos Organic Pins Sliding Against AlSiC MMC Discs
- 2018
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Ingår i: Tribology in Industry. - : Faculty of Engineering, University of Kragujevac. - 0354-8996 .- 2217-7965. ; 40:2, s. 274-282
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Tidskriftsartikel (refereegranskat)abstract
- The friction, wear and particle emission from an AlSiC MMC brake disc/non-asbestos organic brake pad system is studied using a pin-on-disc tribometer. The results show that this unconventional AlSiC MMC brake disc system presents friction performance as good as a conventional cast iron brake disc system. During braking, brake pad materials are transferred to the brake disc surface to form a protective third body tribo-layer, resulting in a negative specific wear rate of the brake disc. A higher contact load is likely to make it easier to generate the tribo-layer. The tribo-layer also seems to depend on the disc surface grinding features and the contact temperature during braking. By reusing an AlSiC MMC disc where the tribo-layer is already formed, the airborne emission in terms of mass is about 50% lower and in terms of number about the same as the conventional brake contact pair under a similar braking condition. Further full-scale studies are suggested to determine the validity of the findings.
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| 5. |
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| 6. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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A pin-on-disc study on the tribology of cast iron, sinter and composite railway brake blocks at low temperatures
- 2019
-
Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; , s. 48-52
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Tidskriftsartikel (refereegranskat)abstract
- Most freight wagons in the EU use cast iron brake blocks. Cast iron brake blocks have a stable braking capability in different environmental conditions, but wear down the wheel tread quickly. Therefore, there is a need to understand the tribology of other brake block materials. A pin-on-disc tribometer placed in a temperature-controlled chamber is used to investigate the tribology of cast iron, sinter and composite railway brake blocks at low ambient temperatures. Pins made from different brake blocks are tested with discs made from steel wheels. Both friction coefficient and wear are evaluated at five different temperatures from + 10 to − 30 °C. The cast iron block demonstrated the greatest wear at − 10 and − 20 °C, due to the ductile-to-brittle transition at low temperatures. The worn graphite from cast iron is likely to become a solid lubricant, reducing the friction at − 10 and − 20 °C. For the composite brake block, a gradual decrease in friction with decreasing temperature was found. The sinter brake block was not sensitive to changes in ambient temperature. The sliding speed in the current study is relatively low and further study at higher speed is suggested in order to evaluate the tribological performance of different brake blocks.
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| 7. |
- Lyu, Yezhe, 1987-
(författare)
-
Abrasive Wear of Compacted Graphite Cast Iron with Added Tin
- 2019
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Ingår i: Metallography, Microstructure, and Analysis. - : Springer. - 2192-9262 .- 2192-9270. ; 8:1, s. 67-71
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Tidskriftsartikel (refereegranskat)abstract
- The abrasive wear behavior of traditional compacted graphite cast iron (CGI) and compacted graphite cast iron with 0.1% tin addition (CGI-Sn) is studied using a pin-on-disk tribometer. The microstructures of these two CGIs were observed by optical microscopy and scanning electron microscopy. The results show that Sn reduces the average size of vermicular graphite and promotes the generation of pearlite. Sn narrows the average lamellar spacing of pearlite. In the wear tests, CGI-Sn yields a decreased wear loss by 16.5% compared with CGI. Both CGI and CGI-Sn show typical abrasive worn morphology, while CGI presents a more severe wear condition in which large fragmentations can be seen. Under the current test condition, Sn is likely to improve the abrasive wear resistance of compacted graphite iron. Further studies of the specific working conditions are needed, such as testing against frictional material in braking systems, to check the validity of the findings.
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| 8. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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Characterization of ultrafine particles from hardfacing coated brake rotors
- 2023
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Ingår i: Friction. - : Tsinghua University. - 2223-7690 .- 2223-7704. ; 11:1, s. 125-140
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Tidskriftsartikel (refereegranskat)abstract
- Automotive brake rotors are commonly made from gray cast iron (GCI). During usage, brake rotors are gradually worn off and periodically replaced. Currently, replaced brake rotors are mostly remelted to produce brand-new cast iron products, resulting in a relatively high energy consumption and carbon footprint into the environment. In addition, automotive brakes emit airborne particles. Some of the emitted particles are categorized as ultrafine, which are sized below 100 nm, leading to a series of health and environmental impacts. In this study, two surface treatment techniques are applied, i.e., high-velocity oxygen fuel (HVOF) and laser cladding (LC), to overlay wear-resistant coatings on conventional GCI brake rotors in order to refurbish the replaced GCI brake rotor and to avoid the remelting procedure. The two coating materials are evaluated in terms of their coefficient of friction (CoF), wear, and ultrafine particle emissions, by comparing them with a typical GCI brake rotor. The results show that the CoF of the HVOF disc is higher than those of the GCI and LC discs. Meanwhile, HVOF disc has the lowest wear rate but results in the highest wear rate on the mating brake pad material. The LC disc yields a similar wear rate as the GCI disc. The ultrafine particles from the GCI and LC discs appeared primarily in round, chunky, and flake shapes. The HVOF disc emits unique needle-shaped particles. In the ultrafine particle range, the GCI and HVOF discs generate particles that are primarily below 100 nm in the running-in period and 200 nm in the steady state. Meanwhile, the LC disc emitted particles that are primarily ∼200 nm in the entire test run.
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| 9. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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Effect of humidity on the tribological behaviour and airborne particle emissions of railway brake block materials
- 2018
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Ingår i: Tribology International. - : Elsevier. - 0301-679X .- 1879-2464. ; 118, s. 360-367
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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Effect of Tin on Microstructure and Mechanical Properties of Compacted Graphite Iron
- 2015
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Ingår i: International Journal of Cast Metals Research. - : Maney Publishing. - 1364-0461 .- 1743-1336. ; 28:5, s. 263-268
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Tidskriftsartikel (refereegranskat)abstract
- This experiment investigated the effect of tin in an amount up to 0.121 wt.% on the microstructure and mechanical properties of compacted graphite iron (CGI). Graphite and matrix evolution was emphasized with the help of scanning electron microscopy. The results indicate that Sn in experimental range reduces graphite size. Pearlite quantity would increase with the increasing Sn and reaches over 95% when Sn is greater than 0.057 wt.%. Sn helps to narrow the lamellar spacing of pearlite from sorbitic pearlite (320 nm) to troostitic pearlite (83 nm) when Sn increases from 0.003 wt.% to 0.057 wt.%. Appropriate Sn addition promotes the tensile strength and impact toughness and the samples containing 0.057 wt.% Sn perform the highest values of 410.7 MPa and 9.11 J/cm2, respectively. Elongation declines with increasing Sn content because of the emergence of more pearlite. Samples containing excessive Sn experience sharply deterioration in mechanical properties due brittle cementite.
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| 11. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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Friction, wear and airborne particle emission from Cu-free brake materials
- 2020
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Ingår i: Tribology International. - : Elsevier. - 0301-679X .- 1879-2464. ; 141
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Tidskriftsartikel (refereegranskat)abstract
- Cu is required to be abated in brake pads due to its toxicity. There are on the market several Cu-free brake pads. These Cu-free brake pads are only evaluated regarding their friction and wear performance, whereas, their airborne particle emissions are not considered. A pin-on-disc tribometer is used to evaluate the friction, wear and airborne particle emission from two Cu-free commercial brake pads used in the Europe. Moreover, a commercial brake pad containing Cu is evaluated as a reference. The results indicate that Cu-free brake pads yield comparable coefficient of friction as the Cu-contained brake pad. All three brake materials result in similar wear to the mating brake rotor. Cu-free brake pads generate more airborne particles than Cu-contained brake pad.
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| 12. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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On black carbon emission from automotive disc brakes
- 2020
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Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502 .- 1879-1964. ; 148
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Tidskriftsartikel (refereegranskat)abstract
- Black carbon, as a series of light-absorbing carbonaceous material, contributes significantly to current global warming. Black carbon has always been considered a product of incomplete combustion of fossil fuels and vegetation. In the road transport sector, combustion exhaust is thought to be the primary source of black carbon. This study uses a pin-on-disc tribometer to simulate automotive disc brake system and investigate its black carbon emission. The results verified the existence of black carbon emission from disc brake system. Brake pad surface treatment and graphite content also have strong influence on black carbon emission of disc brake contact. A scorched brake material features lower black carbon and particulate matter emissions than non-scorched brake materials. Meanwhile, high graphite content in the brake material tends to expedite black carbon emission. Black carbon emission shows a proportional correlation with PM1 levels from disc brake system. The fraction of black carbon in PM1 depends on the surface condition and graphite content of the brake materials. Future studies on the emission levels of black carbon under different traffic conditions and morphology of non-exhaust black carbon is suggested, which is essential for the enactment of relevant legislations and reduce its impact on global warming.
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| 13. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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On the Microstructure and Wear Resistance of Fe-based Composite Coatings Processed by Plasma Cladding with B4C Injection
- 2015
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 41:9, s. 10934-10939
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Tidskriftsartikel (refereegranskat)abstract
- Fe-based composite coatings were fabricated on Q235 steel substrate by plasma cladding. B4C particles were injected at the center and edge of the melting pool as strengthening phase. Scanning electron microscopy and pin-on-disc tribometer were applied to study the microstructure and wear resistance of the coatings. The results showed that the central injected B4C particles dissolved during plasma cladding and cementite generated. Edge injected B4C particles remained and performed metallurgical bonding with the metal matrix. With Fe-based coating containing edge injected B4C particles, wear resistance increased largely and the wear rate became 1/8 of the Q235 substrate. Afterwards, Fe-based coatings with edge injected B4C particles were prepared on real pieces of 50 picks and 12 chutes, which were taken into field probations. Average service lives of the coated picks and chutes increased 3.4 times and 5.6 times, respectively, compared with the conventional 16Mn and 42CrMo pick and chute components.
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| 14. |
- Lyu, Yezhe, 1987-, et al.
(författare)
-
On the relationships among wheel–rail surface topography, interface noise and tribological transitions
- 2015
-
Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 338-339, s. 36-46
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Tidskriftsartikel (refereegranskat)abstract
- Noise from the wheel-rail interface is a troublesome side effect when railway vehicles negotiate rail curves and straight tracks. A laboratory study using two pin-on-disc tribometers to simulate the pure sliding process in a wheel-rail contact investigated the relationships between surface topographies, tribological aspects and emitted noise. The influence of five different initial surface topographies manufactured by polishing and grinding (transverse and circular) was studied. Polished samples yielded the highest friction coefficient and wear rate because of strong adhesion. Samples with manufacturing traces vertical to the sliding direction produced the lowest friction coefficient and wear rate, and were dominated by ploughing and abrasion. Samples with manufacturing marks parallel to the sliding direction exhibited a medium level in both fiction coefficient and wear rate; the wear mechanism was combined ploughing-adhesion. Noise emission followed the same pattern as the friction coefficients: the highest sound pressure levels occurred for the polished samples and the lowest for the samples with transverse manufacturing marks. 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.
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| 15. |
- Lyu, Yezhe, 1987-
(författare)
-
Railway Open System Tribology
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 16. |
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| 17. |
- Lyu, Yezhe, 1987-, et al.
(författare)
-
Recycling of worn out brake pads impact on tribology and environment
- 2020
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Disc brake systems are widely used on commercial vehicles for braking. The brake pads are usually replaced by new ones before being totally worn out. Current methods to deal with the replaced brake pads include landfill and combustion, resulting in a huge waste of resources and increase of CO2 footprint. From a sustainable point of view, this study aims to evaluate the feasibility of recycling replaced brake pads by addressing a protocol recycling procedure. The results show that the recycled brake pads yield similar friction, wear and airborne particle emission to virgin brake pads. A streamlined life cycle assessment is conducted to compare the environmental impacts between producing virgin brake pads and recycling replaced brake pads. Energy consumption and CO2 footprint of the recycled brake pads are 36% and 34% less than virgin brake pads, indicating that recycling could be a promising method of handling replaced brake pads.
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| 18. |
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| 19. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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Tribology and airborne particle emission of laser-cladded fe-based coatings versus non-asbestos organic and low-metallic brake materials
- 2021
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Ingår i: Metals. - : MDPI AG. - 2075-4701. ; 11:11
-
Tidskriftsartikel (refereegranskat)abstract
- Laser cladding is a promising surface treatment for refurbishing worn-out cast-iron brake rotors. Previous studies on laser-cladded brake rotors have demonstrated their extensively higher wear and greater airborne particle emissions, compared with traditional cast iron rotors. In order to overcome this, a commercial non-asbestos organic (NAO) brake material is tested against Fe-based laser-cladded and traditional cast-iron brake rotors. Two low-metallic brake pad materials are also tested as references. The materials’ coefficients of friction, specific wear rates and particle number concentrations are evaluated. The results indicate that the NAO brake material showed lower wear and had fewer particle emissions than the low-metallic brake materials when deployed against both cast iron and laser-cladded brake rotors. The NAO/laser-cladding friction pairing showed wear, particle concentration and fraction of fine particles (sub 1 µm) equivalent to those of the low-metallic/cast-iron friction pairing, creating significant potential for application in refurbishing worn-out cast-iron brake rotors.
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| 20. |
- Lyu, Yezhe, 1987-, et al.
(författare)
-
TRIBOLOGY OF THREE RAILWAY BRAKE BLOCK MATERIALS TESTED AGAINST RAILWAYWHEEL AT LOW TEMPERATURES
- 2018
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Konferensbidrag (refereegranskat)abstract
- Three railway brake block materials, i.e. cast iron, sintered and organic composite, were tested against railway wheel at10, 3, -10, -20 and -30 °C using a pin-on-disc tribometer with regards to the friction and wear performance. At -10 and -20 °C, cast iron tests yielded very high wear losses both on pin and disc samples and low friction coefficient. The largeamount of graphite worn off from the cast iron sample acted as a lubricant. Friction and wear of sintered material arenot sensitive to the change of temperature. Disc sample tested against organic composite at -30 °C showed negativewear loss, indicating that materials were added onto the surface.
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| 21. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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Wear between wheel and rail:A pin-on-disc study of environmental conditions and iron oxides
- 2015
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Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 328-329, s. 277-285
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Tidskriftsartikel (refereegranskat)abstract
- Railways operate in an open environment where temperature, humidity, and the oxidation conditions are subjected to change. An experimental investigation used a pin-on-disc machine to examine the influence of environmental conditions and iron oxides on the wear performance of the wheel-rail contact. The wear mechanisms were analyzed using scanning electron microscopy and found to be highly dependent on the environmental conditions. On clean contacts, adhesive wear is predominant under low-moisture conditions, becoming more serious with decreasing temperature. With high moisture and at room temperature (i.e., 20. °C and 10. °C) oxide flakes would self-produce and protect the pins from severe wear, as oxidative wear is the main wear mechanism. Samples experienced a transformation of the wear mechanism from adhesive to oxidative with increasing humidity on clean contacts. Complex three-body wear in abrasion form has been determined to dominate oxidized contacts. Under dry conditions, pins underwent severe wear appearing as delamination at 20. °C and crushed wear debris at 3. °C. Raising the moisture level helps the pins to avoid severe wear.
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| 22. |
- Ma, Jijie, et al.
(författare)
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A Comparison of Airborne Particles Generated from Disk Brake Contacts : Induction Versus Frictional Heating
- 2020
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Ingår i: Tribology letters. - : SPRINGER/PLENUM PUBLISHERS. - 1023-8883 .- 1573-2711. ; 68:1
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Tidskriftsartikel (refereegranskat)abstract
- Volatile emissions of vehicle brakes relate to the high temperature of the brake friction pair. However, as a passive parameter of braking applications, temperature is usually studied together with other parameters such as sliding speed and load. Heating tests that increase the friction pair temperature with an induction heater instead of friction are proposed in this study to imitate the rise in temperature in friction tests. Non-friction airborne particles produced solely by the high temperature in heating tests were studied in comparison with friction tests. The results confirmed the existence of non-friction airborne particles and they can represent about 4.5% of the total airborne particles in friction tests. The high-temperature behaviour as well as the composition of the non-friction airborne particles is also presented.
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| 23. |
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| 24. |
- Olofsson, Ulf, 1962-, et al.
(författare)
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A pendulum RIG study on airborne transmission and migration of particles from artificial football turf
- 2019
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Ingår i: Proceedings of 10th International Scientific Conference BALTTRIB 2019. - : Vytautas Magnus University. - 2424-5089. ; , s. 126-131
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Konferensbidrag (refereegranskat)abstract
- Artificial football turf is today an increasingly common playing surface for athletics and kids. Its environmental impact is much debated, which is ranked as the second most common source of micro-plastic migration into nature. There are also concerns regarding the spread of inhalable airborne particles, originating from the wear between the football shoe-artificial turf contact. In this study a British pendulum rig is used to simulate the contact between football shoe stud and the artificial turf. The test rig is placed in a clean room environment, to ascertain if there are measurable levels of airborne particles generated in different sizes. The particle concentration was measured for airborne particles in size between 0.3 to 10 μm. In addition, migration studies of micro-plastics were also performed using the same test set up. Three commonly used rubber granule infill materials are tested in this study: SBR, TPE and EPDM. The results show that EPDM generates more airborne particles than the other two materials. Measurable levels of airborne wear particles were noted in the range from 0.3-10 μm. For the migration studies of micro-plastics, TPE generated the largest number of migrated particles.
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| 25. |
- Olofsson, Ulf, 1962-, et al.
(författare)
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A pin-on-disc study of airborne wear particle emissions from studded tyre on concrete road contacts
- 2018
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Ingår i: Wear. - Amsterdam : Elsevier Ltd. - 0043-1648 .- 1873-2577. ; 410-411, s. 165-172
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Tidskriftsartikel (refereegranskat)abstract
- Studded tyres wear surfaces of winter roads, generating inhalable airborne particles. In this study, four concrete road materials and two stud geometries were investigated in terms of wear, road material hardness and airborne particle concentration. The sliding contact between studded tyres and road materials was studied using a pin-on-disc machine in a clean chamber. The results show that the normal load and the stud size have a large influence on the wear and particle emission. It was found that the wear and particle concentration are inversely proportional to the hardness of the aggregate in the road material and proportional to the sliding distance. The particle size distribution has peaks at 0.2 µm, 1 µm and 2 µm.
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| 26. |
- Olofsson, Ulf, 1962-, et al.
(författare)
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Laser Cladding Treatment for Refurbishing Disc Brake Rotors : Environmental and Tribological Analysis
- 2021
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Ingår i: Tribology letters. - New York : Springer Nature. - 1023-8883 .- 1573-2711. ; 69:2
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, grey cast iron disc brake rotors are refurbished by adding a surface layer through laser cladding. Current methods to deal with replaced rotors mainly include remelting, with a minority fraction disposed in landfill. Both approaches result in a huge waste of resources and an increase in CO2 footprint. From a sustainable point of view, this study aims to evaluate the feasibility of refurbishing brake rotors by a combined environmental and tribological performance approach. A streamlined life cycle assessment is conducted to compare the environmental impacts between producing virgin grey cast iron brake rotors and refurbishing replaced brake rotors by laser cladding. It turns out that the energy consumption and CO2 footprint of the laser cladding refurbished brake rotors are 80% and 90% less than the virgin brake rotors. The results show that the refurbished brake rotor yields higher friction compared to the original cast iron utilizing the same pad material. The wear and particle emissions of the disc brake contact are in this study higher for the laser-cladded one compared to the original cast iron one.
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| 27. |
- Olofsson, Ulf, et al.
(författare)
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Open System Tribology in the Wheel-Rail Contact-A Literature Review
- 2018
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Ingår i: Applied Mechanics Review. - : ASME Press. - 0003-6900 .- 1088-8535 .- 2379-0407. ; 69:6
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Forskningsöversikt (refereegranskat)abstract
- 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.
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| 28. |
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| 29. |
- Tu, Minghui, et al.
(författare)
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A comparison of airborne wear particle emission models based on metro station measurements
- 2019
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Ingår i: Proceedings of 10th International Scientific Conference BALTTRIB 2019. - : Vytautas Magnus University. - 2424-5089. ; , s. 150-157
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Konferensbidrag (refereegranskat)abstract
- The main sources of non-exhaust particles around metro systems are the wear from wheel-rail contact, brake contact and the contact between mechanical parts in electric power systems. In order to predict the PM10 levels on underground metro platforms, the relation among time, train frequency and PM10 level should be investigated. Two types of particle emission models have previously been published to determine the PM10 level on underground train platform; these are the linear model and the conservation model. The aim of this study is to compare the results from the two models with a set of field measurements PM10. In 2016, a set of field measurements are performed on four underground metro platforms in Stockholm. The predicted PM10 values from the two models are compared with the measurement data. The accuracy of the two models is analysed and the behaviours of the two models in high and low train frequency regions are separately discussed.
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| 30. |
- Wahlström, Jens, PhD/Docent, 1979-, et al.
(författare)
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A Study of the Effect of Brake Pad Scorching on Tribology and Airborne Particle Emissions
- 2020
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Ingår i: Atmosphere. - : MDPI. - 2073-4433. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- Non-exhaust wear emissions from disc brakes affect the air quality in cities throughout the world. These emissions come from the wear of the contact surfaces of both the pads and disc. The tribological and emissions performance of disc brakes strongly depend on the contact surface characteristics of the pads and discs. The surfaces of conventional pads are scorched by heating it to several hundred degrees to make the resin carbonize down to a few millimetres deep into the pad. This is done to have a shorter run-in period for new pads. It is not known how scorching will affect the amount of airborne particle emissions. Therefore, the aim of the present study is to investigate how pad scorching influence the airborne particle emissions. This is done by comparing the pin-on-disc tribometer and inertia dyno bench emission results from a Cu-free friction material run against a grey cast iron disc. Three types of modified friction material surfaces have been tested: scorched, extra-scorched and rectified. The results show that the level of scorching strongly affects the airborne particle emissions in the initial phase of the tests. Even if the scorched layer is removed (rectified) before testing, it seems like it still has a measurable influence on the airborne particle emissions. The results from the tribometer tests are qualitatively in line with the inertia dyno bench test for about the first forty brake events; thereafter, the airborne particle emissions are higher for the scorched pads. It can be concluded that it seems that the level of scorching has an adverse influence on both the tribological performance and level of particle emissions.
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| 31. |
- Wahlström, Jens, et al.
(författare)
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Contact pressure and sliding velocity maps of the friction, wear and emission from a low-metallic/cast-iron disc brake contact pair
- 2017
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Ingår i: Tribology in Industry. - : Faculty of Engineering, University of Kragujevac. - 0354-8996 .- 2217-7965. ; 39:4, s. 460-470
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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