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  • 1.
    Abbasi, Saeed
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Nanostructured particles in/outside compartment of running train, an on board measurement2013Report (Other academic)
  • 2.
    Abbasi, Saeed
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Non-exhaust Nano particle emission in Rail traffic2010Conference paper (Refereed)
  • 3.
    Abbasi, Saeed
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Towards elimination of airborne particles from rail traffic2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Since the investigation of wear particles from rail transport started in the late 1910s, the high mass concentrations of these particles have prompted concern among researchers interested in air quality. However, effective action has yet to be taken because relevant knowledge is still missing. This thesis provides knowledge of airborne wear particles originating from rail transport. Some aspects of their characteristic parameters, such as size, mass concentration, number concentration, and morphology, were investigated in the field and in laboratory tests. We also discuss means to mitigate non-exhaust emissions, as well as the advantages and disadvantages of various test set-ups in the seven appended journal papers:Paper A reviews recent studies of exhaust and non-exhaust emissions from rail vehicles. The results, measurements, adverse health effects, and proposed or applied solutions presented in this literature are summarized in this paper.Paper B summarizes the results of field tests we conducted. The effects of curve negotiation and braking under different real conditions were investigated in a field test in which on-board measurements were made. The elemental composition and morphology of the particles emitted and their potential sources were also investigated.Paper C describes how a pin-on-disc machine can be used to reproduce real operating conditions during mechanical train braking in a controlled laboratory setting. The results were validated by comparing the field test results with the results of laboratory studies.Paper D presents comprehensive results of laboratory studies of airborne particles from different braking materials. A new index is introduced in this paper, which can be used as a quantitative metric for assessing airborne wear particle emission rates.Paper E describes the effects of using various friction modifiers and lubricants on the characteristics of airborne particles from wheel–rail contact under lubricated and unlubricated conditions.Paper F reports work to simulate thermoelastic instability in the cast-iron braking material. We simulated the fluctuation of the flash temperature by considering the temperature dependency of the material properties and the transformation of the contact state due to thermomechanical phenomena and wear.Paper G reviews new full- and sub-scale measurements of non-exhaust emissions from ground transport. The advantages and disadvantages of on-board measurements, pin-on-disc tests, dynamometer tests, and test rig studies are discussed in this paper.

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    Thesis
  • 4.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Ekstrand-Hammarström, Barbara
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI),.
    Bergström, Ulrika
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI),.
    Bucht, Anders
    Deptartment of Public Health and Clinical Medicine, Umeå University Hospital, Umeå, 901 89, Sweden.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Jansson, Anders
    Department of Applied Environmental Science, Stockholm University, Stockholm, 106 91, Sweden.
    Biological response in lung cells by brake dust from a novel set-up to generate one sourcewear particles2013Conference paper (Refereed)
  • 5.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Jansson, Anders
    Stockholm University, Applied Environmental Science, Stockholm, Sweden.
    Olander, Lars
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Services Engineering.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    A pin-on-disc study of the rate of airborne wear particle emissions from railway braking materials2012In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 284, p. 18-29Article in journal (Refereed)
    Abstract [en]

    The current study investigates the characteristics of particles generated from the wear of braking materials, and provides an applicable index for measuring and comparing wear particle emissions. A pin-on-disc tribometer equipped with particle measurement instruments was used. The number concentration, size, morphology, and mass concentration of generated particles were investigated and reported for particles 10 nm-32 mu m in diameter. The particles were also collected on filters and investigated using EDS and SEM. The effects of wear mechanisms on particle morphology and changes in particle concentration are discussed. A new index, the airborne wear particle emission rate (AWPER), is suggested that could be used in legislation to control non-exhaust emissions from transport modes, particularly rail transport.

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  • 6.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Jansson, Anders
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Particle emissions from rail traffic: a literature review2013In: Critical reviews in environmental science and technology, ISSN 1064-3389, E-ISSN 1547-6537, Vol. 43, no 23, p. 2211-2244Article, review/survey (Refereed)
    Abstract [en]

    Particle emissions are a drawback of rail transport. This work is a comprehensive presentation of recent research into particle emissions from rail vehicles. Both exhaust and non-exhaust particle emissions are considered when examining particle characteristics such as  PM10, and PM2.5 concentration levels, size, morphology, composition, as well as adverse health effects, current legislation, and available and proposed solutions for reducing such emissions. High concentration levels in enclosed rail traffic environments are reported and some toxic effects of the particles. We find that only a few limited studies have examined the adverse health effects of non-exhaust particle emissions and that no relevant legislation exists. Thus further research in this area is warranted.

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  • 7.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olander, Lars
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Services Engineering.
    Larsson, Christina
    Bombardier Transportation Sweden AB, Västerås, Sweden.
    Jansson, Anders
    Stockholm University, Applied Environmental Science, Stockholm, Sweden.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    A field test study of airborne wear particles from a running regional train2012In: IMechE, Part F: Journal of Rail and Rapid Transit, ISSN 0954-4097, Vol. 226, no 1, p. 95-109Article in journal (Refereed)
    Abstract [en]

    Inhalable airborne particles have inverse health affect. In railways, mechanical brakes, the wheel–rail contact, current collectors, ballast, sleepers, and masonry structures yield particulate matter. Field tests examined a Swedish track using a train instrumented with particle measurement devices, brake pad temperature sensors, and speed and brake sensors. The main objective of this field test was to study the characteristics of particles generated from disc brakes on a running train with an on-board measuring set-up.

    Two airborne particle sampling points were designated, one near a pad–rotor disc brake contact and a second under the frame, not near a mechanical brake or the wheel–rail contact; the numbers and size distributions of the particles detected were registered and evaluated under various conditions (e.g. activating/deactivating electrical brakes or negotiating curves). During braking, three speed/temperature-dependent particle peaks were identified in the fine region, representing particles 280 nm, 350 nm, and 600 nm in diameter. In the coarse region, a peak was discerned for particles 3–6 μm in diameter. Effects of brake pad temperature on particle size distribution were also investigated. Results indicate that the 280 nm peak increased with increasing temperature, and that electrical braking significantly reduced airborne particle numbers. FESEM images captured particles sizing down to 50 nm. The ICP-MS results indicated that Fe, Cu, Zn, Al, Ca, and Mg were the main elements constituting the particles.

     

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  • 8.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    A study of friction modifiers on airborne wear particles from wheel-rail contact2012Conference paper (Refereed)
    Abstract [en]

    Wheel-rail contact and its wear process are crucial issues in maintenance and operating of rolling stocks. During wheel-rail contact, materials in mating faces are worn off and some of them transferred to airborne particles. Eventhough the wear process in wheel-rail contact are well-known, few studies have been conducted on the airborne particles from wheel-rail contact.

    The purpose of this study is to investigate the effect of using different friction modifier on the amount of airbotne particles from wheel-rail contact in a laboratory simulation. In this regard, a series laboratory tests were used by using round head pin (R=25mm) and dead weight 40 N in a pin-on-disc machine. This set-up simulates a contact pressure around 750 MPa on the pin head.

    The amount of airborne particles and their characteristics were investigated in dry-contact, and non-dry contacts whereas a lubricant, Binol rail 510 and a friction modifier, tramsilence were used. According to the results, the effects of using Binol rail to reduce the amount of airborne particles were considerable.

  • 9.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Airborne wear particles from train traffic2010Conference paper (Refereed)
  • 10.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Experiences of measuring airborne wear particles from braking materials and wheel-rail contact2012Conference paper (Refereed)
    Abstract [en]

    During braking both of the discs and pads of disc brakes are worn. Since disc brakes are not sealed, some of the generated wear particles can become airborne.  Wheel-rail is also subjected to wear process during braking as well as normal running. They also contribute to generate airborne particles. Several studies have found an association between adverse health effects and the concentration of particles in the atmosphere, so it is of interest to improve our knowledge of the airborne wear particles generated by disc brakes.

    The present work includes results from full scale testing of rail vehicles. Particle size distribution, morphology and elemental contents are presented and discussed for different combinations of disc and pad materials. Due to high back ground concentration levels in field tests, dedicated laboratory test set ups on a reduced scale were designed and utilized for airborne particle studies with zero background level.

    Promising correlation between field test and the lab set up is identified. Different ways of using this test set up for evaluating how the composition of the airborne particles is classified with respect to their health effects are discussed. Furthermore, different ways of using the proposed method to rank and to quantify airborne particle emission factors are presented.

  • 11.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Lack of applicable criteria in non-exhaust emission legislation: AWPER index a practical solution2011Conference paper (Refereed)
  • 12.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olander, Lars
    A field investigation of the size and morphology and chemical composition of airborne particles in rail transport2010Conference paper (Refereed)
  • 13.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olander, Lars
    Larsson, christina
    A field investigation of the size, morphology and chemical composition of airborne particles in rail transport2010Conference paper (Refereed)
    Abstract [en]

    The health effects of inhalable airborne particles are well documented. In the European Union the European Council mandates that the level of airborne particles with a diameter smaller than 10 µm (PM10) must not exceed an annual average of 40 µg/m3. Examples of possible sources from rail transport are mechanical brakes, wheel rail contact, current collectors, ballast, sleepers and masonry structures. In this regard, a series of field tests have been conducted on a regular Swedish track using a regional train instrumented with: particle measurement devices, temperature sensors in brake pads and sensors to measure the magnitude of train speed and a GPS.

    Two sampling points for airborne particles were designated in the train under frame. One of the sampling points was near a pad to rotor disc brake contact and a second global sampling point was chosen under the frame, but not near a mechanical brake or the wheel-rail contact. The first one was highly influenced by brake pad wear debris and the other one was influenced by all of the brake pads, wheel and rail wear debris as well as re-suspension. In each sampling points, three tubes were linked to three particle measurement devices. Two sets of Ptrak, Dustrak and Grimm devices were used. The Ptrak 8525 was an optical particle measurement device which could measure particle diameter in the size interval of 20 nm up to 1 micrometer. The Dustrak was used to measure particle mass concentration. The Grimm 1.109 was an aerosol spectrometer which counted number of particles from 0.25 micrometer to 32 micrometer in 31 intervals. These two Grimm devices were equipped with Millipore filters in the devices outlets to capture particles for further studies on morphology and matter of particles.

    The total number and size distribution of the particles for these two sampling points were registered and evaluated in different situations such as activating and deactivating electrical brake or train curve negotiating.

    During braking, three peaks of 250 nm, 350 nm and 600 nm in diameter, with the 350 nm peak dominating were identified in the fine particle region. In the coarse particle region, a peak of around 3-6 µm in diameter was discovered. The brake pad temperature effects on particle size distribution were also investigated and the results showed that the peak around 250 nm increased. Furthermore, the activation of electrical braking significantly reduced the number of airborne particles.

    A SEM was used to capture the images from collected particles on filters. Furthermore, an ICP-Ms method was used to investigate the elemental contents of the particulates on the filter.  In this case the main contribution belonged to Fe, Si, Al, Ca, Cu, Zn. The higher amount of some elements weights such as calcium, silicon, sodium and aluminum in the global sampling point filters revealed that ballast and concrete sleepers were the main sources for these particles although some of them originated from rail, wheel, brake disc and brake pad as well.

  • 14.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Tritscher, Trosten
    TSI.
    Krinke, Thomas
    TSI.
    On-board study of nano- and micrometer-particle characteristics of a running electric train2013Conference paper (Refereed)
  • 15.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Zhu, Yi
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Pin-on-disc study of the effects of railway friction modifiers on airborne wear particles from wheel-rail contact2013In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 60, p. 136-139Article in journal (Refereed)
    Abstract [en]

    Knowledge of wheel–rail interaction is crucial to wheel and rail maintenance. In this interaction, some of theworn-off material is transformed into airborne particles. Although such wear is well understood, few studiestreat the particles generated. We investigated friction modifiers' effects on airborne particles characteristicsgenerated in wheel-rail contacts in laboratory conditions. Pin-on-disc machine testing with a round-head pinloaded by a dead weight load 40 N simulated maximum contact pressure over 550 MPa. Airborne particlecharacteristics were investigated in dry contacts and in ones lubricated with biodegradable rail grease andwater- and oil-based friction modifiers. The number of particles declined with the grease; the number ofultrafine particles increased with the water-based friction modifier, mainly due to water vaporization.

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    peerreviewad version
  • 16.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Particle emission from rail vehicles: A literature review2012In: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Sage Publications, 2012Conference paper (Refereed)
    Abstract [en]

    Emission of airborne particles is a side effect from rail transport. This work reviews recent research on particle emissions from rail vehicles. Both exhaust and non-exhaust particle emissions are characterized by size, morphology, composition, and size distribution. Current legislation, knowledge of adverse health effects, and available and proposed solutions for emission reductions are also treated. There has been much focus on exhaust emissions, but only a few limited studies have investigated non-exhaust particle emissions, which contain a significant amount of metallic materials. A new method for measuring the airborne wear particle emission rate (AWPER) is proposed as a first step to guide new legislations and to focus further research on non-exhaust airborne emission, i.e., research on the generation mechanisms for particle emissions and their adverse health effects.

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  • 17.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Technical note: Experiences of studying airborne wear particles from road and rail transport2013In: Aerosol and Air Quality Research, ISSN 1680-8584, Vol. 13, no 4, p. 1161-1169Article in journal (Refereed)
    Abstract [en]

    Airborne particles and their adverse effects on air quality have been recognized by humans since ancient times. Current exhaust emission legislations increase the relative contribution of wear particles on the PM levels. Consequently, wearbased particle emissions from rail and road transport have raised concerns as ground transportation is developing quickly. Although scientific research on airborne wear-based particles started in 1909, there is almost no legislation that control the generation of wear-based particles. In addition, there is no accepted and approved standard measurement technique for monitoring and recording particle characteristics. The main objective of this study is to review recent experimental work in this field and to discuss their set-ups, the sampling methods, the results, and their limitations, and to propose measures for reducing these limitations.

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  • 18.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. Department of Mechanical engineering, Golpayegan University of Technology.
    Teimourimanesh, Shahab
    Chalmers.
    Vernersson, Tore
    Chalmers.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Lunden, Roger
    Chalmers.
    Temperature and Thermoelastic Instability at Tread Braking Using Cast Iron Friction Material2013In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 314, no 1–2, p. 171-180Article in journal (Refereed)
    Abstract [en]

    Braking events in railway traffic often induce high frictional heating and thermoelastic instability (TEI) at the interfacing surfaces. In the present paper, two approaches are adopted to analyse the thermomechanical interaction in a pin-on-disc experimental study of railway braking materials. In a first part, the thermal problem is studied to find the heat partitioning between pin and disc motivated by the fact that wear mechanisms can be explained with a better understanding of the prevailing thermal conditions. The numerical model is calibrated using the experimental results. In a second part, the frictionally induced thermoelastic instabilities at the pin-disc contact are studied using a numerical method and comparing them with the phenomena observed in the experiments. The effects of temperature on material properties and on material wear are considered. It is found from the thermal analysis that the pin temperature and the heat flux to the pin increase with increasing disc temperatures up to a transition stage. This agrees with the behaviour found in the experiments. Furthermore, the thermoelastic analysis displays calculated pressure and the temperature distributions at the contact interface that are in agreement with the hot spot behaviour observed in the experiments.

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  • 19.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Teimourimanesh, Shahab
    Chalmers.
    Vernersson, Tore
    Chalmers.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Lunden, Roger
    Chalmers.
    Temperature and thermo-elastic instability of tread braking friction materials2012Conference paper (Refereed)
  • 20.
    Abbasi, Saeed
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Wahlström, Jens
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Olander, Lars
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Services Engineering.
    Larsson, Christina
    Bombardier Transportation Sweden AB, Västerås, Sweden.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    A study of airborne wear particles generated from organic railway brake pads and brake discs2011In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 273, no 1, p. 93-99Article in journal (Refereed)
    Abstract [en]

    Brake pads on wheel-mounted disc brakes are often used in rail transport due to their good thermal properties and robustness. During braking, both the disc and the pads are worn. This wear process generates particles that may become airborne and thus affect human health. The long term purpose of ‘Airborne particles in Rail transport’ project is to gain knowledge on the wear mechanisms in order to find means of controlling the number and size distribution of airborne particles. In this regard, a series of full-scale field tests and laboratory tests with a pin-on-disc machine have been conducted. The morphology and the matter of particles, along with their size distribution and concentration, have been studied. The validity of results from the pin-on-disc simulation has been verified by the field test results. Results show an ultra-fine peak for particles with a diameter size around 100 nm in diameter, a dominant fine peak for particles with a size of around 350 nm in diameter, and a coarse peak with a size of 3-7 μm in diameter. Materials such as iron, copper, aluminium, chromium, cobalt, antimony, and zinc have been detected in the nano-sized particles.

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  • 21.
    Abbott, Andrew
    et al.
    Univ Leicester, Leicester, Leics, England..
    Liu, Sichao
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. KTH Royal Inst Technol, Stockholm, Sweden..
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. KTH Royal Inst Technol, Stockholm, Sweden..
    Watanabe, Seiya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. KTH Royal Inst Technol, Stockholm, Sweden..
    Wishart, James
    Brookhaven Natl Lab, Upton, NY 11973 USA..
    Ionic liquids at interfaces: general discussion2018In: Faraday discussions, ISSN 1359-6640, E-ISSN 1364-5498, Vol. 206, p. 549-586Article in journal (Other academic)
  • 22. Alemani, Mattia
    et al.
    Nosko, Oleksii
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Metinoz, Ibrahim
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    A study on emission of airborne wear particles from car brake friction pairs2015In: SAE International Journal of Materials & Manufacturing, ISSN 1946-3979, E-ISSN 1946-3987, Vol. 9, no 1, p. 147-157, article id 2015-01-2665Article in journal (Refereed)
    Abstract [en]

    The emission of airborne wear particles from friction material / cast iron pairs used in car brakes was investigated, paying special attention to the influence of temperature. Five low-metallic materials and one non-asbestos organic material were tested using a pin-on-disc machine. The machine was placed in a sealed chamber to allow airborne particle collection. The concentration and size distribution of 0.0056 to 10 μm particles were obtained by a fast mobility particle sizer and an optical particle sizer. The temperature was measured by a thermocouple installed in the disc. The experiments show that as the temperature increases from 100 to 300 °C the emission of ultrafine particles intensifies while that of coarse particles decreases. There is a critical temperature at which the ultrafine particle emission rate rises stepwise by 4 to 6 orders of magnitude. For the friction pairs investigated, the critical temperature was found to be between 165 and 190 °C. Below the critical temperature, fine particles outnumber coarse and ultrafine particles, although coarse particles make up the bulk of the particulate matter mass. The friction pairs differ in the ultrafine particle emission rate by 1 to 2 orders of magnitude. Above the critical temperature, ultrafine particles constitute almost 100% of the total particle number and their relative mass contribution can exceed 50%. Analysis of the particle size distributions revealed peaks at 0.19-0.29, 0.9 and 1.7 μm. Above the critical temperature, one more peak appears in the ultrafine particle range at 0.011-0.034 μm.

  • 23.
    Alemani, Mattia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). Brembo S.p.A, Stezzano, Italy.
    Wahlström, Jens
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Matějka, Vlastimil
    Metinöz, Ibrahim
    Söderberg, Anders
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Perricone, Guido
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). Brembo S.p.A, Stezzano, Italy.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Scaling effects of measuring disc brake airborne particulate matter emissions – A comparison of a pin-on-disc tribometer and an inertia dynamometer bench under dragging conditions2018In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 232, no 12, p. 1538-1547Article in journal (Refereed)
    Abstract [en]

    An important contributor to non-exhaust emissions in urban areas is airborne particulate matter originating from brake systems. A well-established way to test such systems in industry is to use inertia dynamometer benches; although they are quite expensive to run. Pin-on-disc tribometers, on the other hand, are relatively cheap to run, but simplify the real system. The literature indicates promising correlations between these two test stands with regard to measured airborne number distribution. Recent studies also show a strong dependency between the airborne number concentration and the disc temperature. However, a direct comparison that also takes into account temperature effects is missing. The aim of this paper is, therefore, to investigate how the transition temperature is affected by the different test scales, under dragging conditions, and the effects on total concentration and size distribution. New and used low-steel pins/pads were tested against cast iron discs/rotors on both the aforementioned test stands, appositely designed for particulate emission studies. A constant normal load and constant rotational velocity were imposed in both test stands. Results show that a transition temperature can always be identified. However, it is influenced by the test scale and the frictional pair status. Nevertheless, emissions are assessed similarly when an equivalent frictional pair status is analysed (e.g. run-in). Further investigations for fully run-in samples on the pin-on-disc should be performed in order to finally assess the possibility of using the tribometers for the initial assessment of different friction materials.

  • 24.
    Alemani, Mattia
    et al.
    KTH.
    Wahlström, Jens
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Industrial Engineering and Management (ITM), Applied Mechanical Engineering (KTH Södertälje). KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    On the influence of car brake system parameters on particulate matter emissions2018In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 396, p. 67-74Article in journal (Refereed)
    Abstract [en]

    The influence of car brake system parameters on particulate matter emissions was investigated using a pin-on-disc tribometer. Samples from a low-steel friction material and a cast iron disc were tested for different sliding velocities, nominal contact pressures and frictional powers. Disc temperatures were also measured. Their impact on total concentration, size distribution, particle coefficient and transition temperature was analysed. Results show that frictional power is the most significant brake system parameter. However, temperature, as a response parameter, is the most influential, inducing a shift towards the ultrafine particulate fraction and raising emissions. A transition temperature, independent of the system parameters, was identified.

  • 25.
    Alfredsson, Bo
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Nordin, E.
    An Elastic-Plastic Model for Single Shot-Peening Impacts2013In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 52, no 2, p. 231-251Article in journal (Refereed)
    Abstract [en]

    A model was developed for impacts of elastic perfectly plastic spherical particles with impact velocities up to 250 m/s. The model is based on the two master curves, for normalized pressure and projected contact area c (2), which both are functions of the representative strain I > at maximum impact. The model and its parameters were fitted to finite element results for elastic perfectly plastic and strain rate-independent materials. It was applied to a wide range of materials with different ratio between yield stress and elastic properties, different ball sizes and impact velocities. The impact model predicted the results from finite element method for contact radius, maximum impact depth in both target and ball as well as remaining impact depth in target and ball. The remaining impact depth was determined from elastic spring back with Hertzian and quadratic pressure at maximum impact. The rebound velocity was also estimated by following the load-deformation path during spring back. If the strain rate-compensated yield stress was used for the master curve parameters, then the model predicted the impact results also for the investigated strain rate-dependent materials.

  • 26.
    Ali, Nashit
    et al.
    Univ Bologna, Dept Ind Engn, Res Lab, Via Umberto Terracini 24, I-40131 Bologna, Italy..
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Engineering Design, System and Component Design.
    Dizdar, Senad
    Halmstad Univ, Box 823, S-30118 Halmstad, Sweden..
    Friction, wear, and airborne particle emissions from rail-wheel contact with laser cladded overlays-A pin-disc tribometer simulation2023In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 518, article id 204635Article in journal (Refereed)
    Abstract [en]

    The present study uses a pin-on-disc tribometer to evaluate friction, wear, and airborne particle emissions for a rail-wheel contact. Test pins from UIC60 900A rail carbon steels were in contact with three types of test discs surfaces: R7 wheel carbon steel, laser cladding overlayed martensitic stainless steel, and laser cladding overlayed Ni-based-8% MnS self-lubricating alloy. Test results show about halving of the coefficient of friction, 0.42 to 0.22, and one ten-power lower specific pin and disc wear of discs with self-lubricating overlay compared to standard railway carbon steel contacts. Using stainless-steel overlayed discs also resulted in one ten-power lower specific disc wear, but pin wear is unchanged. Particle emission for the tests with discs with self-lubricating overlay is constant at almost 200 particles/cm3 while running in the distance is needed for the other tests. Almost all generated airborne wear particles were in the sub-100 nm range. The use of laser-cladded (LC) overlay reduced the number of airborne wear particles in the sub-100 nm range by more than a factor of 10.

  • 27. Almqvist, Andreas
    et al.
    Sahlin, Fredrik
    Larsson, Roland
    Glavatskikh, Sergei
    Luleå University of Technology, Division of Machine Elements.
    On the dry elasto-plastic contact of nominally flat surfaces2007In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 40, no 4, p. 574-579Article in journal (Refereed)
    Abstract [en]

    A model to be used for numerical simulation of the contact of linear elastic perfectly plastic rough surfaces was developed. Energy dissipation due to plastic deformation is taken into account. Spectral theory and an FFT-techique are used to facilitate the numerical solution process. Results of simulations using four two-dimensional profiles with different topographies in contact with a rigid plane for a number loads are reported. From the results it is clear that the real area of contact (Ar) changes almost linearly with load and is only slightly affected by the difference in topography. A plasticity index is defined as the ratio of plastically deformed area (Ap) and Ar. Plastic deformation occurs even at low loads and there is a significant difference in plasticity index between the surface profiles considered. An investigation on how the spectral content of the surface profile influences the results presented is also performed. This is to ensure that the metrological limitations of the optical profilerused to measure the surfaces do not have a significant influence. It is concluded that the highest frequencies of the measured profile have a negligible influence on the real area of contact.

  • 28.
    Alonso, Asier
    et al.
    CAF I+D.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Perez, Javier
    CAF S.A..
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Physical damage mechanisms for uniform wear calculation2018In: Proceedings of the 11th International Conference on Contact Mechanics and Wear of Rail/wheel Systems, CM 2018, Delft, The Netherlands, 2018Conference paper (Other academic)
    Abstract [en]

    This work presents the initial steps given in order to obtain a comprehensive physical model for the specific case of wheel rail contact, which would be able to relate contact conditions, material properties and wear rates. The main advantage of a physical damage wear model is that wheelset an rail manufacturers can perform simulations in order to improve and optimize material properties for different operational cases. The initial work has focused on delaminative wear, starting with the importance and modelling of rough contact, and a comparison against classic smooth contact models. 

  • 29.
    Alvarez-Asencio, Rubén
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Bettini, Eleonora
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nanotribology and Microstructure of a CoCrMo Alloy: A TribologicalProperties Mapping StudyManuscript (preprint) (Other academic)
  • 30.
    Alvarez-Asencio, Rubén
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Tribological Properties Mapping: Local Variation in Friction Coefficient and Adhesion2013In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 50, no 3, p. 387-395Article in journal (Refereed)
    Abstract [en]

    Tribological properties mapping is a new technique that extracts friction coefficient and adhesion maps obtained from lateral atomic force microscope (LAFM) images. By imaging the surface systematically as a function of load, a series of images can be tiled, and pixelwise fitted to a modified Amontons' Law to obtain friction coefficient and adhesion maps. This removes the ambiguity of friction contrast in LAFM imaging which can be a function of the load used for imaging. In ambient laboratory, air and tetradecane, a sample of Vancron(A (R))40, commercial powder metallurgical tool alloy containing nitrogen, have been scanned using a standard silicon cantilever in order to obtain tribological data. The tribological properties mapping provides unique information regarding the heterogeneous alloy microstructure as well as shedding light on the tribological behavior of the alloy.

  • 31.
    Alvarez-Asencio, Rubén
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Sabibi, Majid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Ejnermark, Sebastian
    Ekman, Lars
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Role of Microstructure on Pitting  Corrosion Initiation of an Experimental Tool Alloy: A Peak Force QNM Atomic Force Micrscopy StudyManuscript (preprint) (Other academic)
  • 32.
    Alvarez-Asencio, Rubén
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wallqvist, Viveca
    Kjellin, Mikael
    Leungo, Gustavo
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nordgren, Niklas
    Nanomechanical Properties of Human Skin Studies by AFM and a Novel Hair IndenterManuscript (preprint) (Other academic)
  • 33.
    Andersson, Martin
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    An experimental investigation of spur gear efficiency and temperature: A comparison between ground and superfinished surfaces2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on reliability when testing gear efficiency and on how gear mesh efficiency can be increased without detrimental effects on the gears. Test equipment commonly used in gear research was analysed to identify important parameters for gear efficiency testing. The effect of the bearing model's load-dependent losses on gear mesh efficiency was also investigated. Two different surface finishes of gears, ground and superfinished, were investigated to determine how two different load levels during running-in affect gear mesh efficiency and changes in surface roughness. Efficiency and gear temperature were also measured for ground and superfinished gears with dip lubrication, as well as two different forms of spray lubrication (before and after gear mesh contact).

    Tests on a gear test rig, showed that different assemblies of the same test setup can yield different measurements of torque loss. The applied bearing model had a significant effect on the estimated gear mesh efficiency. The mesh efficiency of ground gears is affected by the running-in procedure, with a higher running-in load resulting in a higher mesh efficiency than a lower load. This effect was not seen for superfinished gears, which show the same gear mesh efficiency for both running-in loads. Gearbox efficiency increased with spray lubrication rather than dip lubrication. The gear mesh efficiency increased, and thus gear temperatures were reduced, when superfinished gears were used rather than ground gears. A lower gear temperature was measured when gears were spray lubricated at the mesh inlet rather than the mesh outlet.

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  • 34.
    Andersson, Martin
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Churning losses and efficiency in gearboxes2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Efficient transmissions systems are key to producing competitive motor vehicles that have a smaller environmental impact. Gears are the main components in vehicle transmissions and although they are already highly efficient, there is still room for improvement. In this study, the focus falls on the lubricant used to create separating films between gears and todissipate heat. When driving, the gears churn this lubricant, giving rise to power losses that are related to the amount and properties of the lubricant. However, any attempt to reduce these losses must not compromise the required lubrication and heat dissipation. Paper A reports on the use of an FZG gear test rig to investigate power losses and heat generation for different gear immersion depths, surface roughness and coatings. The results show that lower gear roughness reduces gear mesh losses and heat generation. A polishing affect was obtained when a non-coated gear ran against a coated gear.The aim of the research reported in paper B was to increase the accuracy of efficiency testing. It investigated how and whether repeated disassembly and re-assembly of the same test equipment, as well as test performance and rig conditions, affect the measured torque loss in an FZG gear test rig. It was shown that the measured torque loss changes between one assembly and another. Repeatability between tests is crucial for accurate conclusions.The aim of the research reported in paper C was to study whether gear efficiency could be increased by a running-in procedure, which would reduce the need for a coolant. A back-to-back gear test rig was used to test two running-in loads. Higher gear mesh efficiency was seen when a higher running-in load was used.

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  • 35.
    Andersson, Martin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Björklund, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    A study of the influence of gear surface roughness and immersion depth on gear efficiency and temperature2014In: Proceedings of the 16th Nordic Symposium on Tribology - NORDTRIB 2014, 2014, p. A 1-A 6Conference paper (Refereed)
  • 36.
    Andersson, Martin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Sosa, Mario
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Efficiency and temperature of spray lubricated superfinished spur gearsArticle in journal (Refereed)
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  • 37.
    Andersson, Martin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Systems and Component Design.
    Sosa, Mario
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Efficiency and temperature of spray lubricated superfinished spur gears2022In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 236, no 11, p. 2283-2291Article in journal (Refereed)
    Abstract [en]

    Gearboxes are one of the most power dense systems used today, and in certain instances their limiting factor is the ability to evacuate heat from the gear contact. This work analyses the efficiency (i.e. heat generation) and tooth temperature in the three lubricating conditions dip, into mesh spray and out of mesh spray for superfinished gears which are then compared to ground gears. A back-to-back gear test rig is employed to test maximum contact pressures at the pitch of 0.59 to 0.96 GPa and pitch velocities from 0.5 to 20 m/s at a controlled lubricant temperature of 90 °C. The results show superfinished gears have higher mesh efficiency and lower gear tooth and bulk temperatures, hence lower heat flux compared to ground gears in all lubricating conditions.

  • 38.
    Andersson, Martin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Sosa, Mario
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Efficiency and temperature of spur gears using spray lubrication compared to dip lubricationIn: Journal of Engineering TribologyArticle in journal (Refereed)
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  • 39.
    Andersson, Martin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Sosa, Mario
    Sjöberg, Sören
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Effect of Assembly Errors in Back-to-Back Gear Efficiency Testing2014In: International Gear Conference 2014: 26th–28th August 2014, Lyon, Woodhead Publishing Limited, 2014, p. 784-793Conference paper (Refereed)
    Abstract [en]

    As gear efficiency is improved in small steps, it is important to be able to distinguish actual improvements from scatter that can occur while testing. An FZG back-to-back gear test rig was used to investigate how the assembly and re-assembly of the same test setup affects the measurements. A spread in loss torque between one assembly and another of the same test setup were observed. Rig conditions also affected the spread in input torque. With knowledge of how the spread in loss torque varies due to assembly, test results could be distinguished between changes due to assembly and actual differences between tests.

  • 40. Athanassiou, N.
    et al.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Wahlström, J.
    Dizdar, Senad
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Simulation of thermal and mechanical performance of laser cladded disc brake rotors2022In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 236, no 1, p. 3-14Article in journal (Refereed)
    Abstract [en]

    Disc brakes wear during braking events and release airborne particulates. These particle emissions are currently one of the highest contributors to non-exhaust particle emissions and introduce health hazards as well as environmental contamination. To reduce this problem, wear and corrosion-resistant disc coatings have been implemented on grey cast iron brake disc rotors by using various deposition techniques such as thermal spraying and overlay welding. High thermal gradients during braking introduce risks of flaking off and cracking of thermally sprayed coatings with adhesive bonding to the substrate. Overlay welding by laser cladding offers metallurgical bonding of the coating to the substrate and other benefits that motivate laser cladding as a candidate for the coating of the grey cast iron brake discs. This study aims to investigate the effect of laser cladding on the thermal and thermo-structural performance of the coated grey cast iron brake discs. Therefore, thermal and thermo-stress analysis with COMSOL Multiphysics 5.6 software is performed on braking events of grey cast iron brake discs as non-coated – reference and laser cladding coated with stainless steel welding consumables. The Results demonstrated that surface temperatures were more localised, overall higher in the laser cladded coating with over three times the stresses attained of reference grey cast iron discs. The output of the simulations has been compared by tests found in the literature. Laser cladding presented higher reliability and braking performance, nonetheless requiring the evaluation of its thermal impact on other system components. 

  • 41. Belyakov, Nikolay
    et al.
    Nosko, Oleksii
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Analytical solution of non-stationary heat conduction problem for two sliding layers with time-dependent friction conditions2016In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 98, p. 624-630Article in journal (Refereed)
    Abstract [en]

    In this article we conduct an overview of various types of thermal contact conditions at the sliding interface. We formulate a problem of non-stationary heat conduction in two sliding layers with generalized thermal contact conditions allowing for dependence of the heat-generation coefficient and contact heat transfer coefficient on time. We then derive an analytical solution of the problem by constructing a special coordinate integral transform. In contrast to the commonly used transforms, e.g. Laplace or Fourier transforms, the one proposed is applicable to a product of two functions dependent on time. The solution is validated by a series of test problems with parameters corresponding to those of real tribosystems. Analysis shows an essential influence of both time-dependent heat-generation coefficient and contact heat transfer coefficient on the partition of the friction heat between the layers. The solution can be used for simulating temperature fields in sliding components with account of this influence.

  • 42. Belyakov, N.S.
    et al.
    Nosko, A.P.
    Heat frictional contact of semi-bounded solids2008In: Motorization and Power Industry in Agriculture, ISSN 1730-8658, Vol. 10A, p. 83-91Article in journal (Refereed)
  • 43. Belyakov, N.S.
    et al.
    Nosko, A.P.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). Bauman Moscow State Technical University, , Russian.
    Mathematical simulation of thermal friction processes under conditions of nonideal contact2009In: High Temperature, ISSN 0018-151X, E-ISSN 1608-3156, Vol. 47, no 1, p. 123-130Article in journal (Refereed)
    Abstract [en]

    Analytical solutions are obtained for problems on unsteady-state thermal conductivity under conditions of nonideal frictional contact of two solid isotropic half-bounded bodies for cases such as a system of two half-spaces, a system of two unbounded cylindrical bodies, and a system of two half-spaces in the presence of volume source of heat release.

  • 44. Belyakov, N.S.
    et al.
    Nosko, A.P.
    Nonperfect thermal contact of friction bodies2010Book (Refereed)
  • 45. Belyakov, N.S.
    et al.
    Nosko, A.P.
    Математическое моделирование неидеального теплового контакта тел трения2008In: 6th Minsk International Heat and Mass Transfer Forum, 2008Conference paper (Refereed)
  • 46. Belyakov, N.S.
    et al.
    Nosko, Oleksii
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). Bauman Moscow State Technical University, Russian.
    Thermoelastic Problem of Friction of Plane-Parallel Layers with Allowance for Nonstationarity of Thermal Processes2010In: Journal of Friction and Wear, ISSN 1068-3666, Vol. 31, no 5, p. 317-325Article in journal (Refereed)
    Abstract [en]

    An unbound quasistatic thermoelasticity problem of the friction of plane-parallel layers with allowance made for their wear is considered. The exact solution of the problem for the transient thermal contact of layers is obtained. The criteria of the thermal-force stability of a tribosystem for various thermal models are studied.

  • 47.
    Bergseth, Ellen
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Influence of gear surface roughness, lubricant viscosity and quality level on ISO 6336 calculation of surface durability2009Report (Other academic)
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  • 48.
    Bergseth, Ellen
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    On tribological design in gear tooth contacts2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The correct tribological design will have a considerable effect on a gear’s service life and efficiency. The purpose of this thesis is to clarify the impact of variation in the gear tooth flank tribological system on the gear contact load capacity – to increase the understanding of how surface topography and lubricant interact.

    In this thesis the variation in surface topography inherent in the manufacturing method has been shown, by experimental work and computer simulations, to be an important factor for the contact condition in the early life of gears. Surface analysis revealed that the formation and composition of surface boundary layers depends strongly on the chemical composition of the lubricant, but also on pre-existing surface boundary layers. Additionally, surface boundary layers play a major role in frictional behaviour, wear and in allowing the lubricant to react properly with the surfaces.

    Paper A presents the current ISO 6336 calculation of surface durability. A robust design approach was used to investigate the extent to which the current standard for calculation of surface durability allows for manufacturing variations and the choice of lubricant.

    Paper B investigates the extent to which a logarithmical profile modification can increase gear contact pressure robustness compared to traditional lead profiles for gears.

    Paper C compares different gear manufacturing methods and their as-manufactured (fresh unworn) surface topographies, using measured surface topographies as input to a contact simulation program.

    Paper D examines surface boundary layer formation and the corresponding wear in relation to different anti-wear additives in an environmentally adapted base oil.

    Papers E and F make use of specimens with surface topographies imitating two gear manufacturing methods (grinding and superfinishing) to be used in a twin-disc and barrel-on-disc machine respectively. The contacts are analysed by friction measurements and simulations combined with methods for surface analysis.

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    On tribological design in gear tooth contacts
  • 49.
    Bergseth, Ellen
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Virtual Hobbing2007Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Hobbing is a widely used machining process to generate high precision external spur and helical gears. The life of thehob is determined by wear and other surface damage. In this report, a CAD approach is used to simulate the machiningprocess of a gear tooth slot. Incremental removal of material is achieved by identifying contact lines. The paper presentsan example of spur gear generation by means of an unworn and a worn hob. The two CAD-generated gear surfaces arecompared and showed form deviations.

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  • 50.
    Bergseth, Ellen
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Henriksson, Mats
    Scania CV.
    Broukhiyan, Parsa
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Sugutur, Lohith
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Nordin, Erland
    Scania CV.
    EFFECTS OF THRUST WASHER BEARING SURFACE CHARACTERISTICS ON PLANETARY GEAR TRAIN WEAR2017Conference paper (Refereed)
1234567 1 - 50 of 369
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