| 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)
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Grey Cast Iron Brake Discs Laser Cladded with Nickel-Tungsten Carbide-Friction, Wear and Airborne Wear Particle Emission
- 2020
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Ingår i: Atmosphere. - Basel : MDPI. - 2073-4433 .- 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. |
- Hjelm, Rikard, et al.
(författare)
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Airborne Wear Particles from Dry Clutches
- 2022
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 13:10
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Tidskriftsartikel (refereegranskat)abstract
- A significant part of non-exhaust particle emissions in cities comes from the wear of vehicle components. Several studies on airborne particles from the wear of disc brakes and tires have been completed. However, few publications can be found in the scientific literature regarding airborne emissions from dry clutches used in road vehicles. With this in mind, this preliminary study designs a clutch tribometer for the generation of airborne wear particles in a controlled environment. The number concentration and the size distribution of airborne wear particles generated from a typical dry clutch used in passenger cars are investigated. The tests are run at a constant rotational speed, and normal load. The results show that the particle number concentration from dry clutches exhibits a running-in period and a steady state, similar to the particle emissions from disc brake contact. A significant number of nanoparticles (aerodynamic diameter < 100 nm) are emitted from the dry clutch contact.
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| 5. |
- Hjelm, Rikard, et al.
(författare)
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Ultrafine particle emissions from dry clutches : number concentration, size distribution and chemical composition
- 2024
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Ingår i: Environmental Science. - : Royal Society of Chemistry (RSC). - 2634-3606. ; 4:1, s. 35-42
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Tidskriftsartikel (refereegranskat)abstract
- Non-exhaust sources, such as brakes, tyres, roads, and clutches, emit a large portion of airborne particles in road transportation, from ultrafine to coarse sizes. While airborne wear particle emissions from brakes and road-tyre contacts have been studied extensively, emissions from clutches have been overlooked. A preliminary study using a novel test rig has indicated that dry clutches also emit airborne wear particles. This paper presents a multi-method for the assessment of ultrafine particles from dry clutches regarding the number concentration, size distribution and chemical composition. The results show that ultrafine particles are emitted both during run-in and at the steady state, featuring a bi-modal size distribution. Elementary analysis shows that the particles consist of several elements, predominately iron, silicon, and sulfur. It can be concluded from this study that ultrafine particles are always generated when the clutch is operated. Clutches in automobiles are shown to produce ultrafine particles, consisting of several metallic elements, which become airborne.
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| 6. |
- Höjer, M., et al.
(författare)
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A noise related track maintenance tool for severe wear detection of wheel-rail contact
- 2016
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Ingår i: Civil-Comp Proceedings. - 1759-3433. ; 110
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- 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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| 8. |
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| 9. |
- 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
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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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| 10. |
- Lyu, Yezhe, 1987-
(författare)
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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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