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  • 101.
    Lewis, Roger
    et al.
    Department of Mechanical Engineering, University of Sheffield.
    Lewis, S.
    Department of Mechanical Engineering, University of Sheffield.
    Zhu, Yi
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Abbasi, Saeed
    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.
    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.
    The Modification of a Slip Resistance Meter for Measurement of Railhead Adhesion2013In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 227, no F2, p. 196-200Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to find a quick, flexible and localised method for determining railhead adhesion. The proposed method is a pendulum rig, which has a rubber pad at the base of a swinging arm. The arm is released and as the rubber pad slides across the contact surface, energy is lost. This loss can be translated into a friction coefficient. Tests have been performed under dry and contaminated conditions, including water, oil and leaf layers both in the laboratory on extracted rail and in the field on live rail. Friction modifiers were also tested. The results of these tests are compared with data obtained using a hand-pushed tribometer. The performed study shows that the pendulum is a viable way to test adhesion levels in the field.

  • 102.
    Lindholm, Per
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Björklund, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Calvo Cortes, Miguel
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Characterization of wear on a cam follower system in a diesel engine2003In: Wear 254, p. 1199-1207Article in journal (Refereed)
    Abstract [en]

    This paper presents an investigation of the running in of the most important contact surfaces of a modern diesel cam follower system. The test equipment used consists of a commercially available cylinder head with an overhead camshaft and valve train system for six cylinders. The load on the contacting surfaces is varied by controlling the fuel injector pumps. The running in is investigated by analysing the changes in topography of the roller, pin and rocker arm of the fuel injector arm. Seven test series were conducted for 1, 10 and 100 h with a variation of the load and speed between a high and low level. The test time was not long enough to be able to see any changes in the surface topography of the roller or pin surfaces. However the wear on the roller bearing surface and the rocker arm bearing surface was significant. Here the surface peak heights are worn off and the surfaces are smoothed out. The observed changes in surface topography are related to the current lubrication regime and the wear is discussed in terms of the λ -value.

  • 103.
    Lindholm, Per
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Björklund, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Svahn, Fredrik
    Method and surface roughness aspects for the design of DLC coatings2006In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 261, no 1, p. 107-111Article in journal (Refereed)
    Abstract [en]

    The design of coatings for highly loaded component contacts, such as bearings, gears and valve train components involves several important factors, including load, friction, lubrication, surface characteristics and material parameters. This paper presents an investigation of the influence of the material, coating thickness and surface roughness on tensional stress levels for coatings that are more compliant than the substrate material. Specifically the effect of multiple asperity contact is studied in three dimensions. The simulation is based on a finite element model where the load is applied as several interacting Hertzian pressure distributions. The results show that the surface structure, in combination with the elastic properties of the coating, has a large influence on the tensional stress level in the coating. The highest tensional stress level in the coating occurs when contact spots almost overlap neighbouring cells and at the same time the size of the contact spots is in the same order of magnitude as the coating thickness.

  • 104.
    Luttropp, Conrad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Johansson, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Improved recycling with life cycle information tagged to the product2010In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 18, no 4, p. 346-354Article in journal (Other academic)
    Abstract [en]

    Rising demand for product means that the recycling of materials is now more important than ever, saving a lot of energy embedded in materials, thus reducing CO(2) emissions. Providing relevant information can raise the recycling efficiency, which is too low at present. A Recycling Information Matrix (RIM) concentrating on Waste Electrical and Electronic Equipment (WEEE) is suggested in order to facilitate and improve materials recycling. Each RIM focuses on a recycling target, and for each type of product a WEEE vector is constructed. The WEEE vector contains nine hexadecimal numbers where core-recycling info is stored. The WEEE vector can provide direct recycling information escorting the product. Another possibility is to individually identify every single product via RFID technology, giving the potential to look for relevant recycling information in databases. This offers the opportunity to add waste-handling information after the product has entered the market. This would be useful, for example, in tracking substances regarded as non-toxic at time of production which might later be proven to be the opposite. This paper is based on study visits at recycling facilities in Sweden and on many student EcoDesign projects including disassembly of consumer products. Research is done on a focused disassembly of dishwashers and on a polymer recycling experiment at a recycling plant for freezers and refrigerators. Possible escort memories are also studied, especially Radio Frequency Identification Devices (RFID).

  • 105.
    Luttropp, Conrad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Johansson, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Vilaplana, Francisco
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Design for material hygiene - An ecodesign strategy for improved recycling of polymers2010In: Proceedings of the 8th International Symposium on Tools and Methods of Competitive Engineering, TMCE 2010, 2010, p. 1223-1231Conference paper (Refereed)
    Abstract [en]

    Recycling of polymers has come into focus lately. Many polymers carry a backpack of energy from manufacturing, which is lost in present recycling of e.g. automotives and small house hold appliances. This calls for higher efficiency in recycling. To take a step in this direction a literature study is made and an experiment at a recycling plant for refrigerators and freezers. A batch of 30m3 of electronic waste was collected and processed in a so-called Hurricane machine. The experiment showed that recycling of polymers can be made on higher levels of efficiency with the used machine, if complemented with sorting and some initial processing before shredding. In order to improve polymer recycling a set of process steps must be designed in order to get secondary polymer fractions that can be used in products.

  • 106.
    Luttropp, Conrad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Lagerstedt, Jessica
    EcoDesign and The Ten Golden Rules: generic advice for merging environmental aspects into product development2006In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 14, no 15-16, p. 1396-1408Article in journal (Refereed)
    Abstract [en]

    The most important moment in product development is when demands and specifications are decided for the product that is being planned. The specification defines the goal for the product development process. It is a very important steering opportunity for the continuing work and for environmentally driven demands that are to be addressed in the product development phase. The designers are said to have the key to sustainable product development through EcoDesign. Many tools have been developed in order to help them to achieve this objective. However, most tools are seldom used primarily because of a lack of sustainability oriented requirements in specifications for products. If there is no demand for improved environmental performance, then there is no need for EcoDesign tools. The lack of market demand for environmentally improved products is therefore, a crucial factor. In other words: It makes no sense to grab a screwdriver from your toolbox if you have a nail in your hand. On the other hand if you have a hammer in your hand you tend to see everything as nails! The hypothesis of this paper is that there is a strong need for a tool to facilitate the integration of reasonable environmental demands into the product development process. The presented tool, The Ten Golden Rules, can be helpful in this effort. A helpful tool must be well adapted to the task and therefore it is important that the individual product developer/designer can develop personal versions from the generic guidelines. The Ten Golden Rules provide such a possibility. They provide a common foundation, for all in the team, which can be used as a base and guidelines for development of situation specific product-design challenges.

  • 107.
    Luttropp, Conrad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Eco Quality Polymers-EQP2011In: Glocalized Solutions for Sustainability in Manufacturing - Proceedings of the 18th CIRP International Conference on Life Cycle Engineering, 2011, p. 482-485Conference paper (Refereed)
    Abstract [en]

    Polymers are materials worth recycling rather than incinerate. This calls for higher efficiency in recycling. To take a stepin this direction a study is made on how much of the polymer fraction of an electric product that is allocated to thehousing of the product.The study showed that a presorting of products according to polymer content of the shell and afterwards a fragmentingprocess where polymers and metals are separated would give a polymer fraction dominated by the housing polymer.

  • 108.
    Lyu, Yezhe
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Bergseth, Ellen
    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.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    TRIBOLOGY OF THREE RAILWAY BRAKE BLOCK MATERIALS TESTED AGAINST RAILWAYWHEEL AT LOW TEMPERATURES2018Conference paper (Refereed)
    Abstract [en]

    Three railway brake block materials, i.e. cast iron, sintered and organic composite, were tested against railway wheel at10, 3, -10, -20 and -30 °C using a pin-on-disc tribometer with regards to the friction and wear performance. At -10 and -20 °C, cast iron tests yielded very high wear losses both on pin and disc samples and low friction coefficient. The largeamount of graphite worn off from the cast iron sample acted as a lubricant. Friction and wear of sintered material arenot sensitive to the change of temperature. Disc sample tested against organic composite at -30 °C showed negativewear loss, indicating that materials were added onto the surface.

  • 109.
    Lyu, Yezhe
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Wahlström, Jens
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Matějka, Vlastimil
    Brembo.
    Söderberg, Anders
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Ranking of conventional and novel disc brake materials with respect to airborne particle emissions2017In: Eurobrake 2017, 2017Conference paper (Refereed)
  • 110.
    Ma, Jijie
    et al.
    College of Engineering, Zhejiang Normal University, China.
    Hedlund-Åström, Anna
    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 Design (Div.).
    Lyu, Yezhe
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Leonardi, Mara
    Department of Industrial Engineering, University of Trento, Italy.
    Wahlström, Jens
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    ECO DESIGN OF BRAKE PADS WITH RECYCLED FRICTION MATERIALS2019Conference paper (Refereed)
  • 111. Marshall, M. B.
    et al.
    Lewis, R.
    Dwyer-Joyce, R. S.
    Olofsson, Ulf
    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.), Machine Elements.
    Experimental characterization of wheel-rail contact patch evolution2006In: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 128, no 3, p. 493-504Article in journal (Refereed)
    Abstract [en]

    The contact area and pressure distribution in a wheel/rail contact is essential information required in any fatigue or wear calculations to determine design life, re-grinding, and maintenance schedules. As wheel or rail wear or surface damage takes place the contact patch size and shape will change. This leads to a redistribution of the contact stresses. The aim of this work was to use ultrasound to nondestructively quantify the stress distribution in new, worn, and damaged wheel-rail contacts. The response of a wheel/rail interface to an ultrasonic wave can be modeled as a spring. If the contact pressure is high the interface is very stiff, with few air gaps, and allows the transmission of an ultrasonic sound wave. If the pressure is low, interfacial stiffness is lower and almost all the ultrasound is reflected. A quasistatic spring model was used to determine maps of contact stiffness from wheel/rail ultrasonic reflection data. Pressure was then determined using a parallel calibration experiment. Three different contacts were investigated; those resulting from unused, worn, and sand damaged wheel and rail specimens. Measured contact pressure distributions are compared to those determined using elastic analytical and numerical elastic-plastic solutions. Unused as-machined contact surfaces had similar contact areas to predicted elastic Hertzian solutions. However, within the contact patch, the numerical models better reproduced the stress distribution, as they incorporated real surface roughness effects. The worn surfaces were smoother and more conformal, resulting in a larger contact patch and lower contact stress. Sand damaged surfaces were extremely rough and resulted in highly fragmented contact regions and high local contact stress.

  • 112.
    Möller, Björn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Andersson, Sören
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Development of a modular mechatronic mechanism test bench2003In: The proceedings of OST, Oulu, Finland, June 2003, 2003Conference paper (Refereed)
  • 113.
    Möller, Björn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Andersson, Sören
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    The influence of friction in the hydraulic cylinders on the behaviour of a manipulator2006In: The proceedings of NordTrib, 2006Conference paper (Refereed)
    Abstract [en]

    In mobile units such as construction machines that handle high loads, hydraulic cylinders are often used to actuate the manipulators. Such machinery is often manually operated, with each cylinder operating separately. However, the increased use of microcomputers opens up the possibility of computer control of the motions of all types of manipulator. Such control would facilitate the implementation of end-point-controlled hydraulic-driven manipulators. It could also reduce the learning time for operators and prolong the life of machines. However, the nonlinear effects of friction in the hydraulic cylinders may be a problem if they disturb the motion of the manipulator arms. There is thus a need to investigate the influence of friction in hydraulic cylinders on manipulator motion.

    This paper reports on the use of a computer model of a hydraulic-powered manipulator arm to simulate the effects of friction, as represented in several different friction models, on the dynamics of a manipulator. The model used was modular and included two hydraulic cylinders, whose motion was influenced by friction in the cylinders. This model and the work reported in this paper are part of a project to investigate the possibility of implementing end-point control.

    A simulation with realistic data revealed that in general the friction in the hydraulic cylinders has only a minor effect on the motion of the manipulator arms. However, very high friction can have a noticeable effect, particularly if the static friction is much higher than the dynamic friction.

  • 114.
    Möller, Björn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Andersson, Sören
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Wikander, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Modularisation of mechatronic mechanisms with dependent degrees of freedom2003In: The preoceedings of ICED August, 2003, Stockholm, Sweden, 2003Conference paper (Refereed)
  • 115.
    Olofsson, Ulf
    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.
    On the identification of wear modes and transitions using airborne wear particles2013In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 59, no SI, p. 104-113Article in journal (Refereed)
    Abstract [en]

    A novel test method was used to identify how contact conditions influence the wear modes and transitions for sliding steel-on-steel contacts. The test equipment was a pin-on-disc tribometer equipped with instruments for counting airborne particles. The results show that the dominant wear mode significantly influences the number of airborne particles generated from the contact. During mild wear few or no measurable airborne particles were generated. The transitional running-in process could also be identified by airborne particle measurement analysis.

  • 116.
    Olofsson, Ulf
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Wahlström, Jens
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Söderberg, Anders
    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 (name changed to Building Service and Energy Systems 2012-03-01).
    Jansson, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Services Engineering (name changed to Building Service and Energy Systems 2012-03-01).
    Airborne Wear Particles from Disc Brakes: A Comparison of Measurements from Cars, Test Stands and Material Tests2008Conference paper (Other academic)
  • 117.
    Olofsson, Ulf
    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.
    Zhu, Yi
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Abbasi, Saeed
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Lewis, Roger
    Lewis, Steve
    Tribology of the wheel rail contact: aspects of wear, particle emission and adhesion2013In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 51, no 7, p. 1091-1120Article in journal (Refereed)
    Abstract [en]

    The wheel−rail contact is a safety critical interface. Wear, particle emission and adhesion are all wheel−rail contact phenomena and are discussed here. All three phenomena are material and system parameters and are linked together. Different countermeasures to one phenomenon such as adhesion enhancement with a friction modifier can increase the wear in the contacting bodies. The wear of railway wheel and rail is linked to the number of airborne particles generated, but the exact number and size distribution of the aerosols particles are unknown. The main objective of this study is to review recent work in this field and to discuss future trends.

  • 118.
    Perricone, Guido
    et al.
    Brembo S.p.A., Stezzano, Italy.
    Alemani, Mattia
    Brembo S.p.A., Stezzano, Italy.
    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), Machine Design (Dept.), Tribologi.
    Olofsson, Ulf
    KTH, Superseded Departments (pre-2005), Machine Design. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    A proposed driving cycle for brake emissions investigation for test stand2019In: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering, ISSN 0954-4070, E-ISSN 2041-2991Article in journal (Refereed)
    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.

  • 119. Perricone, Guido
    et al.
    Matejka, Vlastimil
    Alemani, Mattia
    Valota, Giorgio
    Bonfanti, Andrea
    Ciotti, Alessandro
    Olofsson, Ulf
    Söderberg, Anders
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. 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.), Tribologi.
    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.
    Nosko, Oleksii
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Straffelini, Giovanni
    Gialanella, Stefano
    Ibrahim, Metinoz
    A concept for reducing PM10 emissions for car brakes by 50%2018In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 396, p. 135-145Article in journal (Refereed)
    Abstract [en]

    With regard to airborne particles with an aerodynamic diameter of less than 10 mu m (PM10), in countries in the European Union, the mass of brake emissions equals approximately 8-27% of the total traffic-related emissions. Using a research methodology combining tests at different scale levels with contact mechanics simulations and PM10 chemical characterization, the REBRAKE EU-financed project had the following aims: i) to demonstrate the possibility of reducing the PM10 fraction of the airborne particulate from brake wear by 50 wt%; ii) to enhance the general understanding on the physical and chemical phenomena underlying the brake wear process. The results achieved so far indicate that it is possible to design a disc brake system for a European standard car affording at least a 32 wt% PM10 emission reduction using a standard European pad and a heat-treated rotor. A further reduction to 65 wt% PM10 emission could be achieved with NAO pad material and the same heat-treated disc.

  • 120.
    Perricone, Guido
    et al.
    Brembo S.p.A., 24040 Stezzano (BG), Italy.
    Matĕjka, Vlastimil
    Department of Chemistry, Faculty of Materials Science and Technology, VSB-Technical University of Ostrava, 708 00 Ostrava, Czech Republic.
    Alemani, Mattia
    Brembo S.p.A., 24040 Stezzano (BG), Italy.
    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), Machine Design (Dept.), Tribologi.
    Olofsson, Ulf
    KTH, Superseded Departments (pre-2005), Machine Design. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    A Test Stand Study on the Volatile Emissions of a Passenger Car Brake Assembly2019In: Atmosphere, ISSN 2073-4433, E-ISSN 2073-4433, Vol. 10, no 5, article id 263Article in journal (Refereed)
    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.

  • 121.
    Riva, Gabriele
    et al.
    Brembo Spa, Italy.
    Perricone, Guido
    Brembo Spa, Italy.
    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), Machine Design (Dept.), Tribologi.
    Simulation of Contact Area and Pressure Dependence of Initial Surface Roughness for Cermet-Coated Discs Used in Disc Brakes2019In: Tribology in Industry, ISSN 0354-8996Article in journal (Refereed)
    Abstract [en]

    Friction, wear, and emission performance strongly depend on the contact pressure and area at the interface of the pad and disc. The contact situation at the pad-to-disc interface can be explained by the formation and destruction of mesoscopic sized contact plateaus on the pad surface. Experimental studies report that the initial surface roughness of cermet-coated discs strongly affects friction, wear and emission performance. This is explained by the formation of secondary plateaus on the disc surface. The aim of this work is to extend an existing cellular automaton approach to include the formation of secondary plateaus on the disc surface in order to explain experimental results reported in the literature. First, to investigate the validity of the novel simulation approach, a cermet-coated cast iron disc is tested against a low-met pad material with a pin-on-disc tribometer. The same conditions are used as input in a simulation. Then, the initial disc roughness influence on contact pressure and area of the same cermet-coated disc is compared with results reported in the literature. The topographies of the measured and simulated disc surfaces are qualitatively in line. An initial rougher disc surface results in a considerably lower contact area than does a smother surface.

  • 122.
    Riva, Gabriele
    et al.
    Brembo S.p.A., Stezzano, BG, Italy.
    Valota, Giorgio
    Brembo S.p.A., Stezzano, BG, Italy.
    Perricone, Guido
    Brembo S.p.A., Stezzano, BG, Italy.
    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), Machine Design (Dept.), Tribologi.
    An FEA approach to simulate disc brake wear and airborne particle emissions2019In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 138, p. 90-98Article in journal (Refereed)
    Abstract [en]

    Emissions from disc brake wear adversely affect the air quality in cities. Finite Element Analysis (FEA) approaches focussing on the macroscopic wear of pads and rotors can be found in the literature, but none of these take the wear and emission dependence of the local contact pressure and sliding speed into account. The aim of the present study is to further develop an FEA approach for simulation of macroscopic wear and airborne emission to include the dependences of local contact pressure and sliding speed by implementing wear and emission maps obtained by pin-on-disc tribometer tests. Results from a dyno bench test are compared with simulated results. The simulated rotor and pads wear, and airborne emissions are in line with the measured values.

  • 123.
    Riva, Gabriele
    et al.
    KTH. Brembo Spa.
    Wahlström, Jens
    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.
    A NUMERICAL STUDY OF DISC BRAKES WEAR DEPENDENCE OF ROTOR SURFACE COATING2018Conference paper (Refereed)
    Abstract [en]

    Airborne emissions from disc brakes adversely affect the air quality in urban areas of EU. The emissions come from the wear of the pads and rotors in disc brakes. The wear of disc brakes depends on the contact situation between the pads and rotors. During braking, secondary contact plateaus are created on both the pads and rotors contact surfaces. Literature reports numerical studies of the creation of contact plateaus on the pad surface but no numerical studies known to the authors have taken into consideration the creation of contact plateaus on the rotor surface. Furthermore, experimental studies reported in the literature shows that secondary plateaus are created in the low-lands of the rotor contact surface and that this affects the wear performance. In particular, it has been reported that the creation of secondary plateaus on coated rotors have a relatively large affect the wear and emissions. The aim of this study is therefore to numerically investigate how the creation of contact plateaus on the rotor surface could affect the disc brake wear performance. This is done by expanding an existing simulation tool used for simulation of friction, wear and particle emission, which takes into account the creation of contact plateaus on the pad surface, to include creation of contact plateaus on the rotor surface. One rotor surface that corresponds to a cast iron rotor is compared with one rotor surface that corresponds to a coated rotor. The results are qualitatively in line with observations done in pin-on-disc tribometer tests. It remains to validate the numerical results with data obtained in experiments.

  • 124.
    Riva, Gabriele
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Wahlström, Jens
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Alemani, Mattia
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    A CFD study of a pin-on-disc tribometer setup focusing on airborne particle sampling efficiency2017In: ECOTRIB 2017, 2017Conference paper (Refereed)
    Abstract [en]

    One of the most important measures to evaluate air quality is the presence of particles. Pin-on-disc tribometers are used to study airborne wear particles originating from different sliding contacts in a controlled laboratory environment. One important aspect when measuring airborne particles is to ensure isokinetic sampling conditions. Another important aspect is that the concentration and the particles distribution entering the sampling probe are representative for the emissions generated. It is therefore important to have an estimation of the sampling efficiency of the test system. The aim of this paper is to investigate the particle sampling efficiency of a pin-on-disc tribometer setup. In addition, a modified sampling setup that allows isokinetic sampling is investigated. CFD simulations to investigate air and particle motion were performed for both the existing and the modified configuration. The results show that the velocity field at the outlet does not allow isokinetic sampling for the existing configuration. In the modified configuration a sampling pipe is used to make isokinetic sampling possible. A comparison between the two configurations show that the modified configuration increases the sampling efficiency with almost 40% for ultrafine particles and about 20% for fine and coarse particles. It remains to validate the CFD simulations with experiments.

  • 125. Shah, F. U.
    et al.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Antzutkin, O. N.
    Novel alkylborate-dithiocarbamate lubricant additives: Synthesis and tribophysical characterization2012In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 45, no 1, p. 67-78Article in journal (Refereed)
    Abstract [en]

    Boron-based lubricant additives have recently received significant attention, because of their wear-reducing and frictional properties and low pollution. At the same time, dithiocarbamate complexes with different metals have a long history of being used as multifunctional additives to lubricants. In this study, novel, environmentally friendly additives containing alkylborate and dithiocarbamate groups with alkyl or methylbenzyl substitutes in one molecule were studied. Tribological tests were performed with the additives admixed in a mineral oil using steel-on-steel contacts in a four-ball tribometer. Borate derivatives of different dithiocarbamate ligands were synthesized by several step reactions to investigate tribochemical properties of boron, sulfur, and nitrogen combined in one selected compound. Viscous liquid products were characterized by multinuclear 1H, 13C, and 11B NMR spectroscopy. The surface morphology and the elemental composition of the tribofilms were investigated using an optical profiler and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). It was found that some of these novel compounds provide better antiwear performance and similar frictional properties compared with a commercially available ZnDTP package. Traces of sulfur in the tribofilms formed with both 0.2 and 1.0 wt% of alkylborate-dithiocarbamate compounds in a mineral oil were detected with EDS. 

  • 126.
    Short, Tim
    et al.
    School of Engineering, University of Liverpool, Brownlow Hill, Liverpool L69 3GH, UK.
    Lee-Mortimer, Andrew
    Luttropp, Conrad
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Johansson, Glenn
    School of Engineering, Jönköping University, Sweden.
    Manufacturing, sustainability, ecodesign and risk: Lessons learned from a study of Swedish and English companies2012In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 37, p. 342-352Article in journal (Refereed)
    Abstract [en]

    Previous research suggests that, despite a desire to introduce environmental concerns into New Product Design, many companies in the northwest of England have not done so. In order to understand more about why companies do or do not take on sustainability methodologies, an entirely new and rigorous approach was taken. This paper therefore presents the results of a questionnaire investigating the up-take of Eco/Sustainable Design in manufacturing companies in Sweden - a country that might be considered more environmentally progressive than the UK - and discusses them alongside the results of an identical questionnaire in the UK. The results are presented in the context of risk and risk aversion/management - in particular the risk associated with taking on board Design for Sustainability as a design method or a company strategy. It is found that there is no clear "winner" in sustainability between UK and Swedish engineering companies; there is encouraging news in both countries, with a desire to practice sustainability, but some that is not so good with the number of companies that actually implement relevant methodologies. It is apparent that there are still hindrances and perceived risks preventing companies taking sustainability fully on board, despite the recognition that sustainability is a "good thing"; the importance of the implementation of sustainability has not yet been fully grasped by industry and by those with the responsibility required to effect any changes.

  • 127.
    Simanovska, Jana
    et al.
    Riga technical University.
    Valters, Karlis
    Riga technical University.
    Bazbauers, Gatis
    Luttropp, Conrad
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    An Ecodesign Method for Reducing the Effects of Hazardous Substances in the Product Lifecycle2012In: Latvian Journal of Physics and Technical Sciences, ISSN 0868-8257, Vol. 49, no 3, p. 13-25Article in journal (Refereed)
    Abstract [en]

    Growing evidence on the indoor and outdoor pollution caused by the flow of man-made products urges that the content and leaching of hazardous substances from products shall be minimised. One of the ways to reduce the potential adverse impacts caused by these substances could be via ecodesign − i.e. through the consideration of lifecycle-related environmental aspects during the product development. The authors’ review of the existing ecodesign methods highlights the weakness of these methods in identifying and assessing the health-related and environmental impacts of hazardous substances contained in products, especially with regard to the exposure assessment. Therefore, a new, semi-quantitative screening ecodesign method applicable for different types of products has been developed. The method ranks the most severe hazards based on the classification according to the Globally Harmonised System together with the exposure evaluation, as well as integrates the aspects of material efficiency. This method is suitable for use in the product development process, requiring decisions to be made based on limited information while integrating the main principles of the scientific chemicals risk assessment. Application of the method is demonstrated with a case study on products made of plywood. The method makes it possible to identify needs for and elaboration of ecodesign proposals, and fosters communication and information exchange throughout the supply chain.

  • 128.
    Sjöberg, Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Redogörelse för lagerfriktion i turboladdare2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this study the main objective was to determine the mechanical frictional losses in a standardautomotive turbocharger. For future work, the result should be the basis for a formula describingthe frictional losses in the turbocharger, dependent on its various operation conditions.The methodology used to estimate the frictional losses included numerical simulation, analyticalcalculations and measurement techniques. Isoviscous simulation models for journal bearings andthrust bearing were developed and used to simulate bearing friction. In addition, analyticalcalculations based on Petroff’s equation were used to determine frictional losses. A third methodbased on a calorimetric measurement technique was used to determine the frictional losses andcompare the results from analytical calculations and simulations. The method involvedmeasurement of the oil flow through the turbocharger and the temperature difference of theturbocharger oil between the inlet and outlet. From the measurement and for a given value of theoil heat capacity the total bearing power loss was determined. The cooling water flow to theturbocharger was adjusted to obtain a bearing housing temperature close to the oil temperature inthe bearing housing and so minimize heat transfer between the turbocharger bearing housing andthe oil.The axial force acting on the turbocharger thrust bearing has a great influence on the oil filmthickness in the bearing and so also the frictional losses. The axial force was measured andcalculated to be used as input for friction simulations and to correlate it to other significantparameters. Three different methods were used to determine the force: axial force calculationwith force balance analysis, axial force calculation based on the axial displacement measurementof the turbocharger shaft and axial force measurement with strain gauges.The thrust bearing simulation model gave an approximation of the bearing frictional losses in theturbocharger. However, the results tend to be overestimated due to the isoviscous assumptionIIand the approximation of the oil viscosity based on the assumption that the bearing oiltemperature could be estimated as an average of oil temperature at the inlet and outlet.The measurement of frictional losses was slightly overestimated, which might be a result ofinvalid heat transfer assumptions and inaccurate measured bearing housing and oil temperature.In addition to the approximation of the oil viscosity, this explains the deviation betweensimulated and measured frictional losses.Finally, it was found that the axial force was strongly correlated to the axial displacement of theturbocharger shaft, the pressure before the turbine and the turbocharger rotational speed. Thepressure on the compressor wheel back face is mainly affected by the turbocharger rotationalspeed and is also a large contributor to the total axial force on the turbocharger shaft.

  • 129.
    Sjöberg, Sören
    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.
    Influence of running-in on gear efficiency2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The general trend in gear industry is an increased focus on gear transmission efficiency. This thesis focuses on the understanding of how different gear manufacturing methods – particularly the contribution of the running-in process – affect the surface characteristics and friction response, with the purpose of increasing gearbox efficiency. The thesis consists of a summary and five appended papers.

    The research hypothesis in paper A and paper B was that the dry elastic contact area ratio is a descriptive parameter for the contact condition. Paper A deals with the influence of manufacturing method on the initial contact conditions. The emphasis in paper B is the changes that occur during running-in and correlating these changes to design requirements. Paper C examines the influence of manganese phosphate coating and lubricants, with respect to friction and the risk of scuffing at the initial contact. Paper D examines the effect of running-in load on the friction response for different surfaces. In paper E, the question of whether the load during running-in influences the gear mesh efficiency is further expounded.

    The main conclusions of this thesis are that the running-in influences the gear mesh efficiency; a high running-in load enhances the gear mesh efficiency. The difference in mesh efficiency is in the range of one tenth of a per cent. Thus, the influence of running-in cannot be neglected because it is in the same order of magnitude as reported for other gear efficiency enhancements. Furthermore, the dry elastic contact area ratio presents a descriptive measure of how surface topography influences the contact, at both a global (form deviation) and local (roughness) level. The surface topography caused by the manufacturing method has a significant influence on the contact area ratio. Shaving was found to have the highest contact area ratio, and would therefore be the best choice if deviations from case hardening could be minimised. It was also confirmed that surfaces coated with manganese phosphate raise the limiting load for scuffing failure up to 13 times compared to the uncoated ground equivalent.

  • 130.
    Sjöberg, Sören
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    On the running-in of gears2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The general trend in gear industry, today, is an increased focus on gear transmission efficiency. Gear transmission efficiency losses arise from loaded and unloaded gear contacts, seals, lubricant and bearings. One way of minimising the losses is to lower the lubricant viscosity. This will reduce the speed dependent losses. However, the load dependent losses might increase. To avoid this, the ratio between lubricant film thickness and surface roughness must be maintained, which can be fulfilled by producing smoother gear surfaces. As a starting point for this realisation process, the present manufacturing processes, the design tools and the characteristics of the gear flank interface must be further investigated and developed. This must be achieved with an emphasis on economic production.

    This thesis focuses on our understanding of how different gear manufacturing methods —particularly the contribution of the running-in process—affect the surface characteristics, with the view of increasing gearbox efficiency. The thesis consists of a summary and three appended papers.

    Paper A and paper B discuss the relationship between design parameters and real gear wheel surfaces manufactured with different manufacturing methods. The research hypothesis was that the contact area ratio is a descriptive parameter for the contact condition. Paper A deals with the influence of manufacturing method on the initial contact conditions and also serves as a validation of the simulation program used. The emphasis in Paper B is the changes that occur during running-in, and to correlate these changes to design requirements. Paper C approaches the influences of manganese phosphate-coating and lubricants with respect to friction and the risk of scuffing at the initial contact.

    The main conclusions of this thesis are that the contact area ratio presents a descriptive measure of how surface topography influences the contact, seen at both a global (form deviation) and local (roughness) level. The surface topography caused by the manufacturing method has a significant influence on the contact area ratio. This is an important result, since neither national standards nor commercially available gear evaluation programs handle surface topography on the local scale. Shaving was found to have the highest contact area ratio, and should therefore be the best choice if deviations from case hardening could be minimised. It is also confirmed that gear-like surfaces coated with manganese phosphate have a low coefficient of friction, and raise the limiting load for scuffing failure enormously compared to the ground equivalent.

  • 131.
    Sjöberg, Sören
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Bergseth, Ellen
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Björklund, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Influence of real surface topography on the contact area ratio in differently manufactured spur gears2008In: Proceedings of Tribology 2008: Surface Engineering of Automotive Powertrains for Environmentally Friendly Transport, 2008Conference paper (Refereed)
  • 132.
    Sjöberg, Sören
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sosa, Mario
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Andersson, Martin
    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.
    A study of the running-in and efficiency of ground gearsManuscript (preprint) (Other academic)
  • 133.
    Sjöberg, Sören
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sundh, Jon
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Scuffing resistance of gear surfaces: influence of manganese phosphate and lubricants2009In: Proceedings of 2nd European Conference on Tribology: ECOTRIB 2009, 2009Conference paper (Refereed)
  • 134.
    Sjöberg, Sören
    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.
    Sundh, Jon
    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 Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Scuffing resistance of gear surfaces: influence of manganese phosphate and lubricantsManuscript (preprint) (Other academic)
  • 135.
    Skedung, Lisa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Danerlöv, Katrin
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Johannesson, Carl Michael
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Aikala, Maiju
    Kettle, John
    Arvidsson, Martin
    Berglund, Birgitta
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Tactile perception: Finger friction, surface roughness and perceived coarseness2011In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 44, no 5, p. 505-512Article in journal (Refereed)
    Abstract [en]

    Finger friction measurements performed on a series of printing papers are evaluated to determine representativeness of a single individual. Results show occasionally large variations in friction coefficients. Noteworthy though is that the trends in friction coefficients are the same, where coated (smoother) papers display higher friction coefficients than uncoated (rougher) papers. The present study also examined the relationship between the measured friction coefficients and surface roughness to the perceived coarseness of the papers. It was found that both roughness and finger friction can be related to perceived coarseness, where group data show that perceived coarseness increases with increasing roughness.

  • 136.
    Skedung, Lisa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Danerlöv, Katrin
    Institute for Surface Chemistry (YTK), Stockholm, Sweden.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Johannesson, Carl Michael
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Aikala, Maiju
    Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), Espoo, Finland.
    Kettle, John
    Oy Keskuslaboratorio - Centrallaboratorium Ab (KCL), Espoo, Finland.
    Arvidsson, Martin
    Department of Psychology, Stockholm University, Sweden.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Reproducibility of finger friction, surface roughness and perception of printing papersArticle in journal (Other academic)
  • 137.
    Skedung, Lisa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Duvefelt, Kenneth
    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.
    Young, Jun Chung
    Polymers Division, National Institute of Standards and Technology.
    Stafford, Christopher M.
    Polymers Division, National Institute of Standards and Technology.
    Rutland, Mark
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Tactile friction of controlled fine surface textures: Role of real contact area and adhesionManuscript (preprint) (Other academic)
  • 138.
    Sundh, Jon
    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.), Tribologi.
    Relating contact temperature and wear transitions in a wheel-rail contact2011In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 271, no 1-2, p. 78-85Article in journal (Refereed)
    Abstract [en]

    Earlier in an ongoing research project, we identified wear transitions, mechanisms, and regimes by experimentally testing the sliding part of a wheel-rail contact. Going further, the present study investigates the effects of elevated contact temperature and severe contact conditions corresponding to those of a wheel flange-gauge corner contact.

    Prior studies discussed wear in terms of contact pressure, amount and type of lubricant, sliding velocity, generated airborne particles, wear depth, coefficient of friction, and topographical measurements. This study shifts the focus to contact temperature, elemental and morphological analysis of the airborne particles, and surface-layer microstructure of test specimens by using several analytical techniques (i.e., SEM, FIB, ESCA, and energy mapping).

    As contact severity increased, the bulk temperature of the contacting bodies increased rapidly; this can be related to elevated contact temperature by judging the size and shape of the ultrafine particles generated. After test runs, the contacting bodies were analysed, revealing microstructural surface layer changes and differences in the amount of oxide formed in the immediate surface.

    When the sliding part of the wheel-rail contact under severe contact conditions is experimentally simulated using pin-on-disc methodology, the discussion shifts from analyzing steady-state measurements, such as average wear rate, to more transient behaviours during running-in. Wear transitions occurring during running-in are decisive for the outcome of the rest of the test run, according to the present results.

  • 139.
    Söderberg, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Andersson, Sören
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Simulation of wear and contact pressure distribution at the pad-to-rotor interface in a disc brake using general purpose finite element analysis software2009In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 267, no 12, p. 2243-2251Article in journal (Refereed)
    Abstract [en]

    Passenger car disc brakes are safety-critical components whose performance depends strongly on contact conditions at the pad-to-rotor interface. The interface can be classified as a conformal dry sliding contact. During braking both brake pad and rotor surfaces are worn, affecting the useful life of the brake as well as its behavior. This paper discusses how wear of the pad-to-rotor interface can be predicted using general purpose finite element analysis software. A three-dimensional finite element model of the brake pad and the rotor is developed to calculate the pressure distribution in the pad-to-rotor contact. A wear simulation procedure based on a generalized form of Archard's wear law and explicit Euler integration is used to simulate the wear of the brake pad under steady-state drag conditions.

  • 140.
    Söderberg, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Björklund, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Validation of a simple contact model and its applicability on rough surfaces2006In: Proceedings of 12th Nordic Symposium on Tribology NORDTRIB 2006, 2006Conference paper (Refereed)
  • 141.
    Söderberg, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Björklund, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Validation of a simplified numerical contact model2008In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 41, no 9-10, p. 926-933Article in journal (Refereed)
    Abstract [en]

    Surface roughness tends to have a significant effect on how loads are transmitted at the contact interface between solid bodies. Most numerical contact models for analyzing rough surface contacts are computational demanding and more computationally efficient contact models are required. Depending on the purpose of the simulation, simplified and less accurate models can be preferable to more accurate, but also more complex, models. This paper discusses a simplified contact model called the elastic foundation model and its applicability to rough surfaces. The advantage of the model is that it is fast to evaluate, but its disadvantage is that it only gives an approximate solution to the contact problem. It is studied how surface roughness influences the errors in the elastic foundation solution in terms of predicted pressure distribution, real contact area, and normal and tangential contact stiffness. The results can be used to estimate the extent of error in the elastic foundation model, depending on the degree of surface roughness. The conclusion is that the elastic foundation model is not accurate enough to give a correct prediction of the actual contact stresses and contact areas, but it might be good enough for simulations where contact stiffness are of interest.

  • 142.
    Söderberg, Anders
    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 Design (Div.).
    Andersson, Sören
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Using finite element analysis to predict the brake pressure needed for effective rotor cleaning in disc brakes2008In: SAE Technical Paper 2008-01-2565, USA: SAE , 2008, p. 1-10Conference paper (Refereed)
    Abstract [en]

    This paper presents an approach to simulating wear on both contact surfaces at the pad-to-rotor interface in discbrakes using general purpose finite element software. Itrepresents a first step toward a method of simulating the brake pressure needed to effectively clean the rotor ofunwanted oxide layers. Two simulation cases are presented. The first addresses running-in wear underconstant load and corresponds to repeated brakeapplications at the same constant brake load. Thesecond studies what will happen if a lower load is applied after the contact surfaces have been run-in at ahigher load level. This lower load is applied to wear off an oxide layer after a sequence of repeated stop braking at higher load levels.

  • 143.
    Söderberg, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Spiegelberg, Christer
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Modeling transient behavior of a mechanical system including a rolling and sliding contact2005In: Proceedings of IMECE 1005, 2005 ASME Interantional Mechanical Engineering Congress and Exposition, 2005, p. 229-238Conference paper (Refereed)
    Abstract [en]

    Thefriction and wear of rolling and sliding contacts are criticalfactors for the operation of machine elements such as bearings,gears, and cam mechanisms. In precision machines, for example, themain concern is to compensate for frictional losses, so asto improve control accuracy. In other applications it is oftendesirable to minimize friction losses to improve efficiency, though sometimeshigh friction is desired to prevent sliding and wear. Theaim of this study is to simulate the behavior ofa test equipment and show that simulations can be usedto study and optimize mechanical systems that include rolling andsliding contact. Simulations can be used to study the systemas a whole, as well as the contact conditions. Thetest equipment and the measurement procedure used are described. Inthe simulations, a contact model designed to handle transient contactconditions is integrated into a system model. The results showthat the contact strongly influences the system. The simulations showthat the use of a contact model allows the simulationof systems that contain contacts with different amounts of slip,and that such simulations can be used to study thecontact as well as the system. Surface roughness influences thecontact stiffness and is included in the simulations.

  • 144.
    Söderberg, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Spiegelberg, Christer
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Simulation models of test equipment for measuring transient friction in a rolling and sliding contact2005In: Proceedings of OST ’05 Symposium On Machine Design, 2005Conference paper (Refereed)
    Abstract [en]

    This paper investigates how a model for boundary lubricated rolling and sliding contacts can be integrated in a dynamic rigid body model of a mechanical system in order to improve the accuracy of simulations of system behavior. The system modeled is test equipment for the measurement of transient friction in rolling sliding contact between two discs. Two different models of the system were constructed: one neglecting the rolling and sliding contact and the other integrating it in the system model. In the integrated contact model, the pressure distribution was computed using an elastic foundation model. A brush model was used for the friction calculation. Simulations were performed with both models and validated by experiments. The results show that the contact needs to be included in the model in order to capture the behavior of the system. Since the contact model used can handle both microslip and gross slip, it is applicable to a wide range of contact conditions.

  • 145.
    Söderberg, Anders
    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), Applied Mechanical Engineering (KTH Södertälje).
    Olander, Lars
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Services Engineering.
    Jansson, Anders
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    On Airborne Wear Particles Emissions ofCommercial Disc Brake Materials– A Pin on Disc Simulation2008Report (Other academic)
    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. Four different nonasbestoses-organic (NAO) linings for the U.S. market and four different low metallic linings for the EU market were tested against material from gray cast iron rotors. The result indicates that the low metallic linings are more aggressive to the rotor material then the NAO linings, resulting in higher amount of wear and concentrations of airborne wear particles. But, although there are variations in the measured particle concentrations, similar size distributions were obtained regardless of lining material.

  • 146.
    Tasala Gradin, Katja
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Hedlund-Åström, Anna
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Evaluation of an Eco Audit tool - through an LCA of a novel car disc brake2018In: Proceedings of NordDesign: Design in the Era of Digitalization, NordDesign 2018, The Design Society , 2018Conference paper (Refereed)
    Abstract [en]

    Transport of goods and people is increasing and causing strains on the environment. Road vehicles emit exhaust and non-exhaust emissions. One significant contributor to non-exhaust emissions is particulates generated through wear from braking. The particulates originate from the contact surfaces of the pad and the disc. Particulate emission is a known issue with considerable impacts on plant, animal, and human health. In the EU Horizon 2020 LOWBRASYS (a LOW environmental impact BRAke SYStem) project (LOWBRASYS, 2017), one of the objectives was to design a novel disc brake that reduces particulate generation during braking. One of the results is a novel disc brake with disc and pad-materials that indicate a significant decrease in particulate formation during use. This is accomplished by changing the materials of the contact pair regarding composition and coatings (Wahlström, Lyu, Matjeka, & Söderberg, 2017). Materials used in the disc brakes cause environmental impacts during their life cycle. Some parts and processes need for example critical raw materials such as tungsten, cobalt, and more (European Commission, 2017). This paper evaluates a material selection tool with an environmental perspective for product developers called Eco Audit (Ashby et al. 2008). This tool is featured in the CES Edu Pack software provided by Granta Design, Cambridge University (Granta 2018). The purpose of this study is to evaluate if the Eco Audit tool can provide a fast and valid impact assessment from an LCA perspective. Results of the Eco Audit compared to the SimaPro results indicate that it is possible to make valid conclusions. The validity of the tool is connected to the purpose of the study. If the purpose is to identify critical life cycle phases and environmental impacts, then the tool can accurately aid the user. It could potentially be difficult to make valid conclusions when assessing a product with more complex processes or advanced materials. The tool's strengths are the simplicity and easy accessibility for any user. The trade-off is precision, robustness, and representativeness of the target. 

  • 147.
    Tasala Gradin, Katja
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Poulikidou, Sofia
    Björklund, Anna
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Luttropp, Conrad
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Scrutinising the electric vehicle material backpack2018In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 172, p. 1699-1710Article in journal (Refereed)
    Abstract [en]

    Conventionally the use phase of a road vehicle contributes to more than 70% of the total environmental impact in terms of energy use or emissions of greenhouse gases. This figure is no longer valid concerning electric vehicles and a shift to other life cycle stages and impacts is expected and should be re-evaluated. The goal of this study is to assess the environmental performance of two prototype vehicle drivetrains; an internal combustion engine and an electric motor, from a life cycle perspective. The assessment is performed in a qualitative manner using the Environmentally Responsible Product Assessment (ERPA) matrix. The two vehicles in this study have similar car body construction, providing an excellent opportunity to highlight the significance of material differences in their drivetrains. The internal combustion vehicle demonstrated a better environmental performance in three out of five lifecycle stages (pre-manufacture, product manufacture, and disposal). In all of these stages, the impact of the electric vehicle is determined by the burden of the materials needed for this technology such as rare earth elements (REE) and by the lack of recycling possibilities. The study demonstrated a need to close the material cycle when it comes to Critical Raw Materials (CRM) such as REE which can only be achieved when the technology but also the incentives for material recovery are provided, i.e. by promoting the development of cost-efficient recycling technologies. Moreover, the need for relevant metrics and assessment indicators is demonstrated to be able to compare the two technologies fairly.

  • 148.
    Tornehed, Petter
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Particulate Emissions Associated with Diesel Engine Oil Consumption2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Particulate emissions from diesel engines have been a key issue for diesel engine developers in recent decades. Their work has succeeded in reducing the exhaust particles from the combustion of fuel, which has led to increasing interest in the contribution of particulates from lubrication oil.

    When discussing oil-related particulate emissions, hydrocarbon particles are customarily referred to. This thesis uses a broader definition, in which oil-related particulate emissions are modelled not only by the hydrocarbons, but also include the ash, carbons, and sulphate oil particulate emissions.

    The model developed in the project uses input data as oil consumption and oil ash content combined with tuning parameters, such as the oil ash transfer rate (ash emissions divided by oil consumption and oil ash content). Controlled engine tests have been performed to verify assumptions and fill knowledge gaps. The model can be applied to a variety of diesel engines, although the tuning factors might have to be reset. For example, introducing diesel particulate filters would dramatically reduce the oil ash emissions, since oil ash would accumulate in the filter.

    Oil consumption has played a central role in the present research. The modelling results indicate that special attention should be paid to oil consumption under running conditions with a low in-cylinder temperature, since the oil survival rate is high there.

    Under low-load and motoring conditions, hydrocarbons proved to be the main contributor to oil-related particulate emissions. At high engine load, oil ash emissions were the largest contributor to oil-related particulate emissions.

  • 149.
    Tornehed, Petter
    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.), Tribologi.
    Modelling lubrication oil particulate emissions from heavy-duty diesel enginesIn: Journal of Aerosol Science, ISSN 0021-8502, E-ISSN 1879-1964Article in journal (Other academic)
  • 150. Vernersson, Tore
    et al.
    Lunden, Roger
    Abbasi, Saeed
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    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.
    Wear of Railway brake block materials at elevated temperatures: pin-on-disc experiments2012In: Proceedings of Eurobrake 2012, FISITA, 2012Conference paper (Refereed)
    Abstract [en]

    An experimental study on a pin-on-disc rig is presented where the wear of some brake block materials at controlled elevated disc temperatures are reported. It is found for the three studied organic composite materials that the (specific) wear rate increases radically at a temperature of about 500 oC. For temperatures below 500 oC, the wear rate is found to increase with temperature. The cast iron material shows an increase of the wear rate up to 500 oC, after which a transition in the wear mechanism occurs and the wear rate is decreasing with increasing temperature. The studied sinter material shows a weak dependence of the wear rate with temperature.

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