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Publications (10 of 194) Show all publications
Lyu, Y., Leonardi, M., Wahlström, J., Gialanella, S. & Olofsson, U. (2020). Friction, wear and airborne particle emission from Cu-free brake materials. Tribology International, 141, Article ID 105959.
Open this publication in new window or tab >>Friction, wear and airborne particle emission from Cu-free brake materials
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2020 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 141, article id 105959Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-261640 (URN)10.1016/j.triboint.2019.105959 (DOI)2-s2.0-85072165886 (Scopus ID)
Note

QC 20191011

Available from: 2019-10-09 Created: 2019-10-09 Last updated: 2019-10-11Bibliographically approved
Lyu, Y., Leonardi, M., Ma, J., Wahlström, J., Gialanella, S. & Olofsson, U. (2019). A PIN-ON-DISC STUDY ON THE FRICTION, WEAR AND AIRBORNE PARTICLE EMISSION FROM RECYCLED BRAKE PAD MATERIAL. In: : . Paper presented at Eurobrake 2019.
Open this publication in new window or tab >>A PIN-ON-DISC STUDY ON THE FRICTION, WEAR AND AIRBORNE PARTICLE EMISSION FROM RECYCLED BRAKE PAD MATERIAL
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2019 (English)Conference paper, Published paper (Refereed)
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-254058 (URN)
Conference
Eurobrake 2019
Funder
EU, Horizon 2020, 17182
Note

QC 20190624

Available from: 2019-06-20 Created: 2019-06-20 Last updated: 2019-06-24Bibliographically approved
Lyu, Y., Bergseth, E., Wahlström, J. & Olofsson, U. (2019). A pin-on-disc study on the tribology of cast iron, sinter and composite railway brake blocks at low temperatures. Wear, 48-52
Open this publication in new window or tab >>A pin-on-disc study on the tribology of cast iron, sinter and composite railway brake blocks at low temperatures
2019 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, p. 48-52Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Brake blocks, Composite, Pin-on-disc, Railway, Temperature, Tribology
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-246451 (URN)10.1016/j.wear.2019.01.110 (DOI)000464582200006 ()2-s2.0-85061381732 (Scopus ID)
Note

QC 20190320

Available from: 2019-03-20 Created: 2019-03-20 Last updated: 2019-05-14Bibliographically approved
Perricone, G., Alemani, M., Wahlström, J. & Olofsson, U. (2019). A proposed driving cycle for brake emissions investigation for test stand. Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering
Open this publication in new window or tab >>A proposed driving cycle for brake emissions investigation for test stand
2019 (English)In: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering, ISSN 0954-4070, E-ISSN 2041-2991Article in journal (Refereed) Published
Abstract [en]

Particulate matter emission factors from vehicle brakes are difficult to assess directly from the field. Moreover, there is a lack of a standardized cycle and test stand for evaluating brake emissions. For these reasons, a test cycle was developed from real driving data collected from a car. This new test cycle was implemented on an inertia disc brake dynamometer appositely designed for brake particle emission studies. Results reveal that, for the brake system used as an example, the obtained emission factors for the urban driving conditions studied are comparable to EURO 6 regulations in terms of particle number and comparable to EURO 4 levels in terms of mass with brake emission factors equal to 4.37–6.46 × 1011 particles/km and 44–48 mg/km, respectively.

Place, publisher, year, edition, pages
Sage Publications, 2019
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-254158 (URN)10.1177/0954407019841222 (DOI)2-s2.0-85064091423 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, 324385
Note

QC 20190624

Available from: 2019-06-20 Created: 2019-06-20 Last updated: 2019-06-24Bibliographically approved
Thibblin, A. & Olofsson, U. (2019). A test rig for evaluating thermal cyclic life and effectiveness of thermal barrier coatings inside exhaust manifolds. Paper presented at 9 April 2019 through 11 April 2019. SAE technical paper series, 2019-April(April)
Open this publication in new window or tab >>A test rig for evaluating thermal cyclic life and effectiveness of thermal barrier coatings inside exhaust manifolds
2019 (English)In: SAE technical paper series, ISSN 0148-7191, Vol. 2019-April, no AprilArticle in journal (Refereed) Published
Abstract [en]

Thermal Barrier Coatings (TBCs) may be used on the inner surfaces of exhaust manifolds in heavy-duty diesel engines to improve the fuel efficiency and prolong the life of the component. The coatings need to have a long thermal cyclic life and also be able to reduce the temperature in the substrate material. A lower temperature of the substrate material reduces the oxidation rate and has a positive influence on the thermo-mechanical fatigue life. A test rig for evaluating these properties for several different coatings simultaneously in the correct environment was developed and tested for two different TBCs and one oxidation-resistant coating. Exhausts were redirected from a diesel engine and led through a series of coated pipes. These pipes were thermally cycled by alternating the temperature of the exhausts. Initial damage in the form of cracks within the top coats of the TBCs was found after cycling 150 times between 50°C and 530°C. Temperature calculations showed that, besides evaluating the thermal cyclic life, the test method has the potential to provide a quick ranking of coating materials with respect to thermal insulation by measuring the temperature on the outer surface of the coated pipes. One of the major advantages of the presented test method compared to other methods described in the literature is that it ranks the thermal cyclic life and thermal properties of different coatings under realistic conditions in the correct environment. More cycles and higher temperatures are recommended for future tests, to accelerate the test, as well as evaluate whether the initial cracks in the TBCs will lead to spallation.

Place, publisher, year, edition, pages
SAE International, 2019
Keywords
Automobile engine manifolds, Coated materials, Cracks, Diesel engines, Exhaust manifolds, Oxidation resistance, Thermal fatigue, Thermal insulation, Heavy-duty diesel engine, Lower temperatures, Oxidation resistant coating, Realistic conditions, Substrate material, Temperature calculation, Thermal barrier coating (TBCs), Thermo mechanical fatigues (TMF), Thermal barrier coatings
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:kth:diva-255936 (URN)10.4271/2019-01-0929 (DOI)2-s2.0-85064705377 (Scopus ID)
Conference
9 April 2019 through 11 April 2019
Note

QC 20190816

Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-16Bibliographically approved
Perricone, G., Matĕjka, V., Alemani, M., Wahlström, J. & Olofsson, U. (2019). A Test Stand Study on the Volatile Emissions of a Passenger Car Brake Assembly. Atmosphere, 10(5), Article ID 263.
Open this publication in new window or tab >>A Test Stand Study on the Volatile Emissions of a Passenger Car Brake Assembly
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2019 (English)In: Atmosphere, ISSN 2073-4433, E-ISSN 2073-4433, Vol. 10, no 5, article id 263Article in journal (Refereed) Published
Abstract [en]

Brake-related airborne particulate matter contributes to urban emissions in the transport sector. Recent research demonstrated a clear dependence of the number of ultra-fine particles on the disc brake temperature. Above the so-called transition temperature, the number of ultra-fine particles increases dramatically (several magnitudes). As for exhaust emissions, part of the emissions released during braking can be in the volatile fraction. For this reason, a disc brake test stand specifically designed for aerosol research was equipped with three different aerosol sampling instruments: (i) a standard cascade impactor, (ii) a cascade impactor operating at high temperature with a heated sampling line, and (iii) a standard cascade impactor with a thermodenuder. Tests with a brake assembly representative of European passenger vehicles were executed, and the concentration of released airborne particles was determined. The results showed a decrease by several magnitudes in the concentration (in the size range of below 200 nm) using the cascade impactor operating at 180 °C with the sampling line heated to 200 °C. A further decrease in the concentration of airborne particles with size fractions below 200 nm was measured using a standard cascade impactor with a thermodenuder heated to 300 °C.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-254155 (URN)10.3390/atmos10050263 (DOI)000472677600037 ()
Funder
EU, FP7, Seventh Framework Programme, 324385
Note

QC 20190624

Available from: 2019-06-20 Created: 2019-06-20 Last updated: 2019-07-29Bibliographically approved
Bergseth, E., Höjer, M., Lyu, Y., Nilsson, R. & Olofsson, U. (2019). A Wear Detection Parameter for the Wheel–Rail Contact Based on Emitted Noise. Tribology Transactions, 62(3), 496-503
Open this publication in new window or tab >>A Wear Detection Parameter for the Wheel–Rail Contact Based on Emitted Noise
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2019 (English)In: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 62, no 3, p. 496-503Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
Railway, noise, condition monitoring, wear, wheel–rail contact
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Vehicle Engineering
Research subject
The KTH Railway Group - Tribology; Machine Design
Identifiers
urn:nbn:se:kth:diva-249942 (URN)10.1080/10402004.2019.1576957 (DOI)000466145500001 ()2-s2.0-85064477098 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme
Note

QC 20190522

Available from: 2019-04-23 Created: 2019-04-23 Last updated: 2019-05-22Bibliographically approved
Ma, J., Hedlund-Åström, A., Olofsson, U., Lyu, Y., Leonardi, M. & Wahlström, J. (2019). ECO DESIGN OF BRAKE PADS WITH RECYCLED FRICTION MATERIALS. In: : . Paper presented at Eurobrake 2019.
Open this publication in new window or tab >>ECO DESIGN OF BRAKE PADS WITH RECYCLED FRICTION MATERIALS
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2019 (English)Conference paper, Published paper (Refereed)
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-254061 (URN)
Conference
Eurobrake 2019
Funder
EU, Horizon 2020, 17182
Note

QC 20190624

Available from: 2019-06-20 Created: 2019-06-20 Last updated: 2019-06-24Bibliographically approved
Lin, J., Bergstedt, E., Lindholm, P., Shi, Z. & Olofsson, U. (2019). In situ measurement of gear tooth profile during FZG gear micropitting test. SURFACE TOPOGRAPHY-METROLOGY AND PROPERTIES, 7(1), Article ID 015018.
Open this publication in new window or tab >>In situ measurement of gear tooth profile during FZG gear micropitting test
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2019 (English)In: SURFACE TOPOGRAPHY-METROLOGY AND PROPERTIES, ISSN 2051-672X, Vol. 7, no 1, article id 015018Article in journal (Refereed) Published
Abstract [en]

According to the GFKT-C/8.3/90 FZG gear micropitting test procedure, the average value of gear tooth profile deviation is used as the failure criterion. Typically, gear tooth profile deviation is measured using a gear measuring machine. In order to do that during the FZG gear test, the gears tested have to be disassembled from, and assembled to the test rig. This process is tedious, time-consuming and is likely to add uncertainty to the testing results. An in situ gear tooth profile measurement method has been developed and applied in FZG gear micropitting tests. The tooth profile of the tested gear was measured in-situ in the gearbox before, during and after each load stage of the gear micropitting test. An algorithm was developed to fit the measured profile to its theoretical shape. Furthermore, a tooth profile change evaluation algorithm was developed for monitoring the evolution of the tooth profile during the duration of the test. The whole methodology was exemplified with a wrought gear test case run to pitting damage.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2019
Keywords
gear, micropitting test, tooth profile, FZG
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-247824 (URN)10.1088/2051-672X/ab0637 (DOI)000460459900001 ()
Note

QC 20190327

Available from: 2019-03-27 Created: 2019-03-27 Last updated: 2019-03-27Bibliographically approved
Lin, J., Bergstedt, E., Lindholm, P., Shi, Z. & Olofsson, U. (2019). In situ measurement of gear tooth profile during FZG gear micropitting test (vol 7, 015018, 2019). SURFACE TOPOGRAPHY-METROLOGY AND PROPERTIES, 7(2), Article ID 029601.
Open this publication in new window or tab >>In situ measurement of gear tooth profile during FZG gear micropitting test (vol 7, 015018, 2019)
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2019 (English)In: SURFACE TOPOGRAPHY-METROLOGY AND PROPERTIES, ISSN 2051-672X, Vol. 7, no 2, article id 029601Article in journal (Refereed) Published
Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2019
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-252370 (URN)10.1088/2051-672X/ab0f92 (DOI)000467482900001 ()
Note

QC 20190613

Available from: 2019-06-13 Created: 2019-06-13 Last updated: 2019-06-13Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2489-0688

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