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  • 1. Abbasi, Saeed
    et al.
    Jansson, Anders
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Olander, Lars
    Olofsson, Ulf
    Sellgren, Ulf
    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.

  • 2. Abbasi, Saeed
    et al.
    Olander, Lars
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Larsson, Christina
    Olofsson, Ulf
    Jansson, Anders
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Sellgren, Ulf
    A field test study of airborne wear particles from a running regional train2012In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 226, no 1, p. 95-109Article in journal (Refereed)
    Abstract [en]

    Inhalable airborne particles have inverse health effects. 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, 350, 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. Field emission scanning electron microscope images captured particles sizing down to 50 nm. The inductively coupled plasma mass spectrometry results indicated that Fe, Cu, Zn, Al, Ca, and Mg were the main elements constituting the particles.

  • 3.
    Jansson, Anders
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Olander, Lars
    Olofsson, Ulf
    Sundh, Jon
    Söderberg, Anders
    Wahlström, Jens
    Ultrafine Particle Formation from Wear2010In: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044, Vol. 9, no 1, p. 83-88Article in journal (Refereed)
    Abstract [en]

    Much attention is given to the consequences of airborne particles on human health and well-being. Wear is one source of airborne particles and contributions in the urban environments from wheel-to-rail contacts and disc brakes cannot be neglected. Traditionally, mechanical wear has been associated with the generation of particles of diameters of some microns. However, the research described has found ultrafine particle generation from wear processes. Particle generation from wear was measured under controlled laboratory conditions. The wear was created through sliding contact in a tribometer (type pin-on-disc) with different materials and with different sliding velocities and pressures, to represent rail traffic and automobile disc braking. Particle concentrations and size distributions in the air were determined for particle diameters from 10 nm up to more than 10 mu m. For most materials and conditions three particle size modes were found: one at 50-100 nm, one at a few hundred nm and one at a few mu m particle diameter.

  • 4.
    Lidén,
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Jansson, Anders
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    A Simple Theoretical Model for the Air Flow and Particle Penetration in a Modified Horizontal Elutriator with Plates of Unequal Lengths2007In: Ann. occup. Hyg., Vol. 51, p. 379-383Article in journal (Refereed)
  • 5. Mattson, M.
    et al.
    Andersson, L.T.
    Holmqvist, L.
    Vesterberg, O.
    Jansson, A
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Alm Kubler, K.
    Ekebom, A.
    Birch and grass pollen allergens in filtered office office indoor air2008In: Indoor Air 2008: Copenhagen, Denmark, 2008Conference paper (Refereed)
  • 6. Olofsson, U.
    et al.
    Wahlström, J.
    Söderberg, A.
    Olander, L
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Jansson, A
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Airborne Wear Particles from Disc Brakes: a Comparison of Measurements from Cars, Test Stands and Material Tests2008In: IMechE Tribology 2008: July 8-9, 2008Conference paper (Refereed)
  • 7. Olofsson, Ulf
    et al.
    Olander, Lars
    Jansson, Anders
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    A Study of Airborne Wear Particles Generated From a Sliding Contact2009In: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 131, no 4, p. 044503-044507Article in journal (Refereed)
    Abstract [en]

    Recently, much attention has been paid to the influence of airborne particles in the atmosphere on human health. Sliding contacts are a significant source of airborne particles in urban environments. In this study airborne particles generated from a sliding steel-on-steel combination are studied using a pin-on-disk tribometer equipped with airborne-particle counting instrumentation. The instrumentation measured particles in size intervals from 0.01  µm to 32  µm. The result shows three particle size regimes with distinct number peaks: ultrafine particles with a size distribution peak around 0.08  µm, fine particles with a peak around 0.35  µm, and coarse particles with a peak around 2 or 4  µm. Both the particle generation rate and the wear rate increase with increasing sliding velocity and contact pressure.

  • 8. Olofsson, Ulf
    et al.
    Olander, Lars
    Jansson, Anders
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Towards a model for the number of airborne particles generated from a sliding contact2009In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 267, no 12, p. 2252-2256Article in journal (Refereed)
    Abstract [en]

    Recently, much attention has been given to the influence of airborne particles in the atmosphere on human health. Sliding contacts are a significant source of airborne particles in urban environments. Airborne particles may be generated by disc brakes and wheel-rail contacts. This paper presents a new model for determining the number of airborne particles generated by a sliding contact. Previously presented data from a pin-on-disc tribometer equipped with airborne particle counting instrumentation was used to verify the model. The derived particle rate is proportional to the load for the ball bearing steel material evaluated. Furthermore, the model incorporates three particle regimes with distinct number peaks; one with ultra fine particles with a peak around 0.08 μm, one with fine particles with a peak around 0.35 μm and one with coarse particles with a peak around 2 μm, that can be used to rank the number of generated particles from different material combinations and contact conditions.

  • 9. Schneider, T.
    et al.
    Jansson, Anders
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Jensen, KA.
    Kristjansson, V.
    Luotamo, M.
    Nygren, O.
    Savolainen, K.M.
    Skaug, V.
    Thomassen, Y.
    Tossa-vainen, A..
    Tuomi, T.
    Wallin, H.
    Evaluation and control of occupational health risks from nanoparticles2007Report (Other (popular science, discussion, etc.))
  • 10. Sundh, Jon
    et al.
    Olofsson, Ulf
    Olander, Lars
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Jansson, Anders
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Wear rate testing in relation to airborne particles generated in a wheel-rail contact2009In: Lubrication Science, ISSN 0954-0075, Vol. 21, no 4, p. 135-150Article in journal (Other academic)
    Abstract [en]

    This study examines the relationship between generated airborne particles and wear rate in the wheel-rail contact. The wheel-rail contact is experimentally simulated by using pin-on-disc testing to determine the difference in wear rate between selected contact conditions. Wear is discussed both in tribological terms and by using the wear categories prevalent in the railway industry, namely, mild, severe and catastrophic wear. The discussion is based on wear depth, the coefficient of friction, topographical measurements and measurements of airborne particles generated in the contact. The tests were performed under selected loading conditions representative of different contact conditions in a real wheel-rail contact. The results indicate that wear rates vary with the contact conditions arising from different types of triggered wear transitions. This is emphasised by the number and size of the airborne particles generated.

  • 11. Wahlström, J.
    et al.
    Söderberg, A.
    Olander, L
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Jansson, A
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Olofsson, U.
    Airborne wear particles from passenger car disc brakes – a comparison of measurements in field tests, disc brake assembly test stand and material test stand2008In: SAE 28th Annual Brake Colloquium and Exhibition: October 12-15, 2008Conference paper (Refereed)
  • 12.
    Wahlström, Jens
    et al.
    KTH.
    Söderberg, Anders
    KTH.
    Olander, Lars
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Jansson, Anders
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Olofsson, Ulf
    KTH.
    A pin-on-disc simulation of airborne wear particles from disc brakes2010In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 268, no 5-6, p. 763-769Article in journal (Refereed)
    Abstract [en]

    A novel test method was used to study the concentration and size distribution of airborne wear particles from disc brake materials. A pin-on-disc tribometer equipped with particle counting instruments was used as test equipment. Material from four different non-asbestos organic (NAO) pads and four different low metallic (LM) pads were tested against material from grey cast iron rotors. The results indicate that the low metallic pads cause more wear to the rotor material than the NAO pads, resulting in higher concentrations of airborne wear particles. Although there are differences in the measured particle concentrations, similar size distributions were obtained. Independent of pad material, the characteristic particle number distributions of airborne brake wear particles have maxima around 100, 280, 350, and 550 nm.

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