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  • 201. Björling, Marcus
    et al.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Marklund, Pär
    Kassfeldt, Elisabet
    EHL friction mapping: the influence of lubricant, roughness, speed and slide to roll ratio2010Inngår i: 14th Nordic Symposium on Tribology: NORDTRIB 2010 : Storforsen, Sweden, June 8-11, 2010, Luleå: Luleå tekniska universitet, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A friction test is conducted in a WAM ball on disc test rig. The output from the test is friction coefficient versus entrainment speed and slide-to-roll ratio presented as a 3D friction map. A number of parameters are varied while studying the friction coefficient; surface roughness, base oil viscosity and EP additive package. Entrainment speed, slide to roll ratio and oil temperature are also varied. The results show that the mapping is efficient in showing the different types of friction that may occur in an EHL contact. The results also show that the friction behaviour can be strongly influenced by changing surface roughness as well as base oil viscosity, EP additive content and operating temperature.

  • 202.
    Björling, Marcus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Marklund, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Kassfeldt, Elisabet
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Elastohydrodynamic lubrication friction mapping: The influence of lubricant, roughness, speed, and slide-to-roll ratio2011Inngår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 225, nr 7, s. 671-681Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A friction test is conducted in a Wedeven Associates Machine ball-on-disc test rig. The output from the test, friction coefficient versus entrainment speed and slide-to-roll ratio (SRR), is presented as a three-dimensional friction map. A number of parameters are varied while studying the friction coefficient; surface roughness, base oil viscosity, base oil type, and extreme pressure (EP) additive package. Entrainment speed, SRR, and oil temperature are also varied. The results show that the mapping is efficient in showing the different types of friction that may occur in an elasto-hydrodynamic lubrication contact. The results also show that the friction behaviour can be strongly influenced by changing surface roughness as well as base oil viscosity, base oil type, EP additive content, and operating temperature.

  • 203.
    Björling, Marcus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Marklund, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    On the effect of DLC coating on full film EHL friction2013Konferansepaper (Fagfellevurdert)
  • 204.
    Björling, Marcus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Miettinen, J.
    Group of Tribology and Machine Elements, Department of Materials Science, Tampere University of Technology.
    Marklund, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Lehtovaara, A.
    Group of Tribology and Machine Elements, Department of Materials Science, Tampere University of Technology.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    The correlation between gear contact friction and ball on disc friction measurements2015Inngår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 83, s. 114-119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Running experiments with full-size gearboxes from the actual application has the advantage of giving realistic results in terms of power losses. The drawback is extensive costs, lengthy testing, and the difficulty in differentiating between load dependent and load independent losses, and which losses are coming from the gears, seals, bearings or synchronizers. In this work, the correlation between friction measurements conducted in a ball-on-disc machine and friction measurements conducted in a back-to-back gear rig is investigated. The correlation between the gear tests and the ball-on-disc tests were reasonably good in terms of absolute values, and the shape of the friction curves were similar, indicating that the ball-on-disc measurements to a large extent are capturing the behavior of the gear contact

  • 205.
    Björling, Marcus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Miettinen, Juha
    Group of Tribology and Machine Elements, Department of Materials Science, Tampere University of Technology.
    Marklund, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Lehtovaara, Arto
    Group of Tribology and Machine Elements, Department of Materials Science, Tampere University of Technology.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    The correlation between gear contact friction and ball on disc friction measurements2016Konferansepaper (Fagfellevurdert)
  • 206.
    Björling, Marcus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Minami, Ichiro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Sundararajan, Bharath
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Environmentally acceptable lubricants for marine applications2018Konferansepaper (Fagfellevurdert)
  • 207.
    Björling, Marcus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Shi, Yijun
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    DLC and Glycerol: Superlubricity in Rolling/Sliding Elastohydrodynamic Lubrication2019Inngår i: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 67, nr 1, artikkel-id 23Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low friction is one of the most important parameters for the development of machine components and machines with high efficiency. Many of the common machine components of today such as gears, rolling element bearings and cam-followers are defined by their non-conformal contacts leading to high-contact pressures, typically 1–4 GPa. The lubrication of such contacts is usually called elastohydrodynamic lubrication (EHL). Diamond-like carbon (DLC) coatings and glycerol have individually been shown to produce low friction in boundary, mixed and full film lubrication. A few studies have been conducted using both glycerol and DLC-coated surfaces to achieve even lower friction in pure sliding boundary-lubricated contacts. However, the literature is lacking studies of how the combination of glycerol and DLC performs in non-conformal rolling/sliding contacts where many common machine components operate. Such a study is presented in this article where a ball-on-disc test rig is used to investigate the performance of the combination of DLC and glycerol at pressures up to 1.95 GPa at various entrainment speeds and slide-to-roll ratios. The investigation shows that the DLC-glycerol combination provides very low friction values, in some cases, below the superlubricity threshold of 0.01, possibly shown for the first time at such high pressure in a non-conformal rolling/sliding contact. The low friction mechanism in full film lubrication is a combination of the low pressure-viscosity and high temperature-viscosity sensitivity of glycerol in combination with thermal insulation of the DLC coating and is presented as thermally assisted liquid superlubricity.

  • 208.
    Björling, Marcus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Yijun, Shi
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Glycerol and Diamond-Like-Carbon in Elastohydrodynamic Lubrication2018Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Lubrication and surface engineering plays a vital part in the efficiency of machine components. By using low friction fluids and low friction coatings the efficiency of machine components can be improved dramatically. Glycerol is an example of a fluid with extraordinary low friction characteristics in various systems. Diamond like carbon (DLC) coatings have also been shown to reduce friction in a variety of tribological interfaces. In this study, the elastohydrodynamic performance of glycerol with DLC coated surfaces has been investigated in rolling sliding contacts at high pressures and high slide-to-roll ratios. The DLC-glycerol system is compared to a steel-synthetic oil system and the differences are significant.

  • 209.
    Björling, Marcus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Yijun, Shi
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Glycerol and DLC in Elastohydrodynamic Lubrication2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Lubrication and surface engineering plays a vital part in the efficiency of machine components. By using low friction fluids and low friction coatings the efficiency of machine components can be improved dramatically. Glycerol is an example of a fluid with extraordinary low friction characteristics in various systems. Diamond like carbon (DLC) coatings have also been shown to reduce friction in a variety of tribological interfaces. In this study, the elastohydrodynamic performance of glycerol with DLC coated surfaces has been investigated in rolling sliding contacts at high pressures and high slide-to-roll ratios. The DLC-glycerol system is compared to a steel-synthetic oil system and the differences are significant.

  • 210.
    Björling, Marcus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Yijun, Shi
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Glycerol and DLC in Elastohydrodynamic Lubrication2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Lubrication and surface engineering plays a vital part in the efficiency of machine components. By using low friction fluids and low friction coatings the efficiency of machine components can be improved dramatically. Glycerol is an example of a fluid with extraordinary low friction characteristics in various systems. Diamond like carbon (DLC) coatings have also been shown to reduce friction in a variety of tribological interfaces. In this study, the elastohydrodynamic performance of glycerol with DLC coated surfaces has been investigated in rolling sliding contacts at high pressures and high slide-to-roll ratios. The DLC-glycerol system is compared to a steel-synthetic oil system and the differences are significant.

  • 211.
    Bodin, Anders
    Luleå tekniska universitet.
    Bevameter: development of device to characterize the chatacteristics of soft terrain2000Inngår i: Proceedings, 8th European conference of ISTVS : June 18 - 22, 2000, Umeå, Sweden: International Society for Terrain-Vehicle Systems. Ed. by Iwan Wästerlund / [ed] Iwan Wästerlrund, Swedsh Univ. of agricultural sciences , 2000, s. 1-8Konferansepaper (Fagfellevurdert)
  • 212.
    Bodin, Anders
    Luleå tekniska universitet.
    Development of a tracked vehicle to study the influence of vehicle parameters on tractive performance in soft terrain1999Inngår i: Journal of terramechanics, ISSN 0022-4898, E-ISSN 1879-1204, Vol. 36, nr 3, s. 167-181Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes a new special tracked vehicle for use in studying the influence of different vehicle parameters on mobility in soft terrain; particularly muskegg and deep snow. A field test in deep snow was carried out to investigate the influence of nominal ground pressure on tractive performance of the vehicle. The vehicle proved useful for studying vehicle parameters influencing the tractive performance of tracked vehicles. The tests show that the nominal ground pressure has a significant effect on the tractive performance of tracked vehicles in deep snow. The decrease in drawbar pull coefficient when the nominal ground pressure is increased and originates at about the same amount from a decrease of the vehicle thrust coefficient, an increase of the belly drag coefficient and an increase of the track motion resistance coefficient.

  • 213.
    Bodin, Anders
    Luleå tekniska universitet.
    Improving the mobility performance of tracked vehicles in deep snow2002Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Improving the mobility of tracked vehicles in deep snow requires an increase in the knowledge and understanding of the design parameters which influence the tractive performance. This relates particularly to the new vehicle requirements of increased payload to vehicle weight ratio, improved fuel economy and reduced life cycle costs. It has been the aim of the research presented in this thesis to improve the understanding of how different vehicle design parameters affect the tractive performance of tracked vehicles in deep snow. A new tracked vehicle was developed to enable experimental studies of different vehicle design parameters in deep snow. The vehicle was skid steered with a hydrostatic transmission and driven by a five-cylinder diesel engine. The vehicle design made it possible to vary several vehicle design parameters in the field, one at a time, without affecting the others. To be able to compare vehicle tests from different snow conditions and also to be able to simulate vehicle performance in snow, the strength properties of the snow are required. A bevameter was developed to characterise the pressure-sinkage relationship, the response to unloading- reloading and the shear stress-shear displacement of the snow. The idea of using the bevameter technique was to measure the terrain data under loading conditions similar to those encountered by an off-road vehicle. The bevameter developed consisted of a hydraulic cylinder with a piston of one metre stroke through the cylinder. A hydraulic motor with a planetary gear was attached to the upper end of the rod piston, which exerted the turning torque in the shear test. The cylinder exerted the normal force in both the pressure-sinkage and the shear test. The most important finding was that the drawbar pull strongly increased when the initial rear track angle was reduced. This was due to both an increased thrust between the tracks and the snow and to a reduced track motion resistance. The increased performance originated from a reduced load transfer from the last roadwheel to the others when the initial rear track angle was reduced. The tractive performance increased continuously with decreasing initial rear track angle. The tractive performance not only increased when the idler made contact with the snow, thus increasing the track contact length, but increased continuously with a decrease in the initial rear track angle prior to the idler contacting the snow. Another important finding was that the drawbar pull increased when the centre of gravity was moved forward, especially when the idler was in the elevated position. An increased belly ground clearance and a reduced initial angle of the vehicle belly both provided improved mobility performance of the vehicle. This was due to both increased thrust and reduced belly resistance, which in both cases, originated from a vertical load transfer from the rear of the belly to the tracks. The experimental tests of the influence of the initial rear track angle on the tractive performance were compared with corresponding simulations using the Nepean Tracked Vehicle Performance Model for Microsoft Windows, (NTVPMwin). The simulation also showed an increased drawbar pull when the initial rear track angle was reduced. However, there was difference in the absolute level of the drawbar pull with the simulation results showing a 6-10% higher drawbar pull.

  • 214.
    Bodin, Anders
    Luleå tekniska universitet.
    Study of the influence of vehicle parameters on tractive performance in deep snow2001Inngår i: Journal of terramechanics, ISSN 0022-4898, E-ISSN 1879-1204, Vol. 38, nr 1, s. 47-59Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes an experimental study of tractive performance in deep snow, carried out with a new special skid steered tracked vehicle, developed by Bodin [1]. The vehicle design parameters studied include the influence of the ground clearance of the vehicle belly and the longitudinal location of the centre of gravity on tractive performance in deep snow, as well as the effect of initial track tension. The most important results from the test show that an increase in the ground clearance has a positive effect on the drawbar pull, originating from a greater increase in the thrust than in the track motion resistance and a slight decrease in the belly drag. Tests of the longitudinal location of the centre of gravity show that a location ahead of the midpoint of the track contact length is to be preferred. The drawbar pull increases with the centre of gravity moving forward. This is due to a reduced track motion resistance, a slight decrease in the belly drag and an almost constant vehicle thrust. The reason for the decreased track motion resistance and belly drag with the centre of gravity located ahead of the midpoint of the track contact length is a decreased vehicle trim angle.

  • 215.
    Bodin, Anders
    Luleå tekniska universitet.
    Tracked vehicles: the influence of design parameters on the tractive performance in deep snow1999Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    To increase the mobility of tracked vehicles in deep snow with the payload capacity preserved and the maintenance costs kept low, improved design is required. To optimise new tracked vehicles intended to operate in deep snow, more knowledge about the vehicle design parameters that affect the tractive performance in deep snow is needed, especially regarding the design of the track assembly and of the vehicle belly. A new tracked vehicle has been developed for use in studying the influence of different vehicle parameters on mobility in soft terrain, particulary on muskegs and in deep snow. The vehicle makes it possible to vary several design parameters in the field, and it is equipped with transducers to measure the vehicle thrust, track motion resistance, belly resistance, drawbar pull, the trim angle of the vehicle and the slip between the tracks and snow.Experimental studies show that increased nominal ground pressure significantly decreases the tractive performance of the vehicle. Increasing the ground clearance and moving the centre of gravity well ahead of the midpoint of the track contact length increase the drawbar pull of the vehicle

  • 216.
    Bodin, Anders
    Luleå tekniska universitet.
    Tracked vehicles-the influence of design parameters on the tractive performance in deep snow1999Inngår i: Tribologia : Finnish Journal of Tribology, ISSN 0780-2285, Vol. 18, nr 3, s. 6-12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new tracked vehicle has been developed for studying the influence of different vehicle parameters on mobility in soft terrain, particularly on muskegs and in deep snow. The vehicle is skid steered with a hydrostatic transmission, driven by a five-cylinder diesel engine. The vehicle makes it possible to vary several design parameters in the field, and it is equipped with transducers to measure the vehicle trust, track motion resistance, belly resistance, drawbar pull, the trim angle of the vehicle and the slip between the tracks and snow

  • 217.
    Bodin, Anders
    Luleå tekniska universitet.
    Vehicle performance in deep snow under late winter conditions: Influence of belly configuration2002Inngår i: 6th ISTVS Asia-Pacific Conference : and 22nd Annual Meeting of the Japanese Society for Terramechanics ; Joint Meeting ; Bangkok, Dec. 3-5, 2002 ; Proceedings, 2002, s. 306-315Konferansepaper (Fagfellevurdert)
  • 218.
    Bodin, Anders
    Luleå tekniska universitet.
    Vehicle performance in deep snow under late winter conditions: Influence of pressure distribution along the track-snow contact length2002Inngår i: 6th ISTVS Asia-Pacific Conference: and 22nd Annual Meeting of the Japanese Society for Terramechanics ; Joint Meeting ; Bangkok, Dec. 3-5, 2002 ; Proceedings, 2002, s. 295-305Konferansepaper (Fagfellevurdert)
  • 219.
    Braceras, Inigo
    et al.
    Tecnalia Res & Innovat, Mikeletegi Pasealekua 2, San Sebastian, Spain.
    Ibanez, Inigo
    Tecnalia Res & Innovat, Mikeletegi Pasealekua 2, San Sebastian, Spain.
    Taher, Mamoun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Mao, Fang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    del Barrio, Andres
    Tecnalia Res & Innovat, Mikeletegi Pasealekua 2, San Sebastian, Spain.
    Saenz De Urturi, Saioa
    Tecnalia Res & Innovat, Mikeletegi Pasealekua 2, San Sebastian, Spain.
    Berastegui, Pedro
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Andersson, Anna M.
    ABB AB, Corp Res, Insulat & Mat Technol, SE-72178 Vasteras, Sweden.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    On the electro-tribological properties and degradation resistance of silver-aluminum coatings2018Inngår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 414, s. 202-211Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Contact materials in sliding electrical applications must possess low electrical contact resistance, low friction and wear coefficients, and high degradation resistance to the surrounding media. Silver coatings are commonly used in such applications despite their shortcomings. This work has focused on the study of alternative silver-aluminum coatings deposited by PVD. The main findings include the strong dependence of the tribological performance on the concentration of Al and hence the phases present in the coatings. Besides, the wear mechanism was found to be affected by the working media, either on air or insulating oil. Results have shown that for full HCP phase coatings (Ag67Al33), wear rates are lowest, with no adhesive wear and good surface sulphidation resistance, though with some proclivity to oxidation, coupled with a moderate increase in the electrical contact resistance.

  • 220.
    Brewe, David E.
    et al.
    Lewis Research Center.
    Jacobson, Bo
    Luleå tekniska universitet.
    The effect of vibration amplitude on vapour cavitation in journal bearings1987Inngår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 115, nr 1-2, s. 63-73Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Computational movies were used to analyse the formation and collapse of vapour cavitation bubbles in a submerged journal bearing. The effect of vibration amplitude on vapour cavitation was studied for a journal undergoing circular whirl. The boundary conditions were implemented using Elrod's algorithm which conserves mass flow through the cavitation bubble as well as the oil film region of the bearing. In the calculations, 0.1 ε εmax, where ε is the instantaneous eccentricity and 0.4 εmax 0.9 for the different cases studied. For the case 0.1 ε 0.4, no vapour cavitation occurred. For the case in which 0.1 ε < 0.9, vapour cavitation was present for 76% of the total time

  • 221. Brewe, D.E.
    et al.
    Jacobson, Bo
    Luleå tekniska universitet.
    Effect of vibration amplitude on vapor cavitation in journal bearings1986Inngår i: Nordic Symposium on Tribology, Lulea, Sweden, 15-18 Jun. 1986, Luleå: Högskolan i Luleå , 1986Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Computational movies were used to analyze the formation and collapse of vapor cavitation bubbles in a submerged journal bearing. The effect of vibration amplitude on vapor cavitation was studied for a journal undergoing circular whirl. The boundary conditions were implemented using Elrod's algorithm, which conserves mass flow through the cavitation bubble as well as through the oil-film region of the bearing. The vibration amplitudes for the different cases studied resulted in maximum eccentricity ratios ranging from 0.4 to 0.9. The minimum eccentricity ratio reached in each case was 0.1. For the least vibration amplitude studied in which the eccentricity ratio varied between 0.1 and 0.4, no vapor cavitation occurred. The largest vibration amplitude (i.e., eccentricity ratios of 0.1 to 0.9) resulted in vapor cavitation present 76 percent of one complete orbit.

  • 222.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Flores-Ruiz, Francisco
    Centro de Investigacion y de Estudios Avanzados del I.P.N., Unidad Queretaro.
    Novel method for in-situ and simultaneous nanofriction and nanowear characterization of materials2015Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 34, artikkel-id 043201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nowadays, there is an increased need to know the nanotribological properties of protectivecoatings used in part devices operating under nano- and microcontact situations, e.g., hard diskdrives, magnetic heads, microelectromechanical systems and microsensors, etc. Therefore, there isa demand for instruments and methods testing friction and wear at the nano- and microscales. Inthis work, the authors present a new methodology to measure simultaneously the friction, and wearof a surface. The authors have designed an experiment, where a probe is permanently scanning a10 lm track in a reciprocal movement. Different loads are applied in order to obtain thetopographic information which is used to calculate the wear rate and roughness evolution. Forcelateral sensors register simultaneously the friction force variations. The experimental input data areinformation vectors that contain: load (lN), friction force (lN), vertical Z displacement (nm),lateral X displacement (nm), and time (s). The data are processed using a simple program runningin MathLabVR which eliminates the thermal drift. The software output gives the resulting frictioncoefficient, track roughness, and wear rate as a function of the running cycles of the probe. Thenew method builds a novel bridge to relate tribological mechanisms at different scales

  • 223.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. SKF Res and Dev Ctr, Netherlands.
    Lorusso, Antonella
    Univ Salento, Italy; Ist Nazl Fis Nucl, Italy.
    Perrone, Alessio
    Univ Salento, Italy; Ist Nazl Fis Nucl, Italy.
    Karoutsos, Vagelis
    Univ Patras, Greece.
    Vainos, Nikolaos A.
    Univ Patras, Greece.
    Gontad, Francisco
    Univ Salento, Italy; Ist Nazl Fis Nucl, Italy.
    Nanomechanical and microtribological properties of yttrium thin films for photocathode engineering2019Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, nr 3, artikkel-id 031507Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The authors study the nanomechanical and microtribological properties of yttrium (Y) thin films deposited by pulsed laser deposition on Cu polycrystalline substrates. Nanoindentation tests reveal that such films have a high hardness of H = 2.3 GPa and a reduced elastic modulus of 71.7 GPa with respect to the Cu substrates. The friction coefficient between a diamond tip and the Y film reaches a steady state value of mu similar to 0.34, lower than that for the Cu (mu similar to 0.38). Moreover, nano-scratch experiments show that Y films are more scratch-resistant than the Cu substrates, probably due to their greater hardness, higher elastic recovery, and lower friction coefficient. Their results confirm that the mechanical and tribological properties of the Y films are suitable for designing and fabricating scratch-resistant hybrid photocathodes and can reduce instabilities and unwanted discharges in the cavity of the radio-frequency gun. Furthermore, the low surface roughness and the low work function of the material are important characteristics for a photocathode based on the Y thin film for the production of high-brightness electron beams. Published by the AVS.

  • 224.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. CNRS, France; Tecnosud Rambla Thermodynam, France; SKF Res and Technol Dev Ctr, Netherlands.
    Nedelcu, Dumitru
    Gheorghe Asachi Tech Univ Iasi, Romania.
    Mazurchevici, Simona
    Gheorghe Asachi Tech Univ Iasi, Romania.
    Glenat, Herve
    CNRS, France; Tecnosud Rambla Thermodynam, France.
    Grillo, Stefano
    CNRS, France; Tecnosud Rambla Thermodynam, France; Univ Perpignan, France.
    Tribological and Nanomechanical Behavior of Liquid Wood2019Inngår i: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 141, nr 2, artikkel-id 022001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During the last decades, there has been an increased interest in the use of lignin-based composites following the ideas of developing green materials for fossil-based raw materials substitution. The biopolymer Arboform is a mixture of lignin, plant fibers, and additives, which is nowadays successfully used in many applications. As a thermoplastic, it can be molded and is therefore also called "liquid wood." In this paper, we report a study comparing the nanomechanical and tribological properties of Arboform (AR), and Aramid-reinforced Arboform (AR-AF) composite biopolymers. The samples were produced in an industrial-scale injection molding machine. Nanoindentation experiments have revealed that, in both series of biopolymer samples, an increase in temperature or a change in the injection direction from 0 deg to 90 deg produces an increase in hardness. On the other hand, Youngs modulus is slightly affected by the increase in temperature, and not affected by the injection angle. Tribological characterization has shown that all samples, except the AR-AF injected at 175 degrees C, present noticeable wear and have a similar friction coefficients mu similar to 0.44-0.49 at Hertzian contact pressures p(0) between 90 and 130 MPa. Interestingly, the reinforced polymer produced at 175 degrees C shows no wear and low friction of mu similar to 0.19 at p(0)=90 MPa. Our results show that the reinforced Arboform biopolymers are a good candidate to replace other polymers in many mechanical and tribological applications.

  • 225.
    Burkhart, Christoph
    et al.
    Institute of Machine Elements, Gears & Transmissions (MEGT), University of Kaiserslautern.
    Johansson, Jens
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Uukonsari, Jan
    R&D, Vattenfall AB.
    Prakash, Braham
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Performance of lubricating oils for wind turbine gear boxes and bearings2018Inngår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 232, nr 1, s. 62-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, the friction and wear properties of six different new and used wind turbine gear oils (ISO VG 320), with different base oil formulations and additives packages, were investigated. For that purpose, a four-ball tribometer and an Optimol SRV were used. Moreover, the lubricants extreme pressure properties were also evaluated, using the same four-ball tribometer. The study also includes a characterization of the lubricants. The main objective was to compare the new and used gear oils in order to identify performance differences and predict oil change intervals. The results indicate that a use of 3 to 4 years is within the lifetime of the lubricant.

  • 226.
    Bäckström, Mikael
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
    Koptioug, Andrei
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
    Tinnsten, Mats
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
    People and Skis2006Inngår i: Science-First Hand, ISSN 1810-8520, nr 3, s. 110-125Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 227.
    Bååth, Lars
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Maskinteknisk produktframtagning (MTEK), Fotonik.
    Rosén, Bengt-Göran
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Towards New Interferometer Technology for Surface Metrology2012Inngår i: Proceedings of the 12th International Conference of the European Society for Precision Engineering and Nanotechnology: June 4th - 7th [8th] 2012, Stockholm, Sweden. Vol. 1 / [ed] P. Shore, H. Spaan & T. Burke, Bedford: EUSPEN , 2012, Vol. 1, s. 158-161Konferansepaper (Fagfellevurdert)
    Abstract [en]

    There is an increasing requirement from manufacturing industries for improved technologies to measure surface topography. New instruments have to be accurate; robust to be used on the industry floor; non-invasive; automatic; and sufficiently fast to be used in real time as well as to simultaneously measure over a large area. The industrial applications are plenty:

    • On-line quality control of machined parts,
    • Direct feed back to the manufacturing process,
    • Analysis and selection of surface texture/structure.

    This paper presents new developments in interferometer techniques for new robust area-based topographic instruments.

  • 228.
    Cabanettes, Frederic
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Fahlgren, Lars
    Volvo Car Corporation, Gothenburg, Sweden .
    Hoerig, Torsten
    Nanofocus AG, Oberhausen, Germany.
    Rosén, Bengt-Göran
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Global and local mapping of motor blocks liners roughness for the analysis of honing performance2014Inngår i: Journal of physics, ISSN 1742-6588, Vol. 483, nr 1, artikkel-id 012009Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The manufacturing and finishing (honing) of cylinder liners for the automotive industry is a constant challenge in order to reduce friction losses and oil consumption. A better knowledge of surfaces generated during plateau honing is then required for optimization of the process. Despite a well-known and controlled honing process, variations in surface roughness appear at both global (due to honing tool wear) and local (TDC, middle stroke, BDC) scales and need to be mapped and analysed. The following paper proposes to map the global and local variations in roughness by using a confocal 3D measuring equipment able to measure and scan any area of a cylinder liner. Six motor blocks (five liners each) are evaluated with twenty topography measurements per liner. In total, six hundred 3D measurements of size 1×1 mm are performed and roughness parameters are computed. The results show that some parameters do correlate with the honing tool wear specific to each cylinder. Experimental models could be built. Furthermore surface roughness varies significantly over the axial length of the liners due to waviness deviations combined with a lack of flexibility of the honing tool in axial direction. © Published under licence by IOP Publishing Ltd.

  • 229.
    Cabanettes, Frederic
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS). Halmstad Univ, Sch Business & Engn, SE-30118 Halmstad, Sweden..
    Rosén, Bengt Göran
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Topography changes observation during running-in of rolling contacts2014Inngår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 315, nr 1-2, s. 78-86Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The automotive industry and the design of engines are strongly ruled by performance and legislation demands. In the valve train, besides the main function (transformation of rotation to translation movements) to fulfill, new requirements in environmental demands and performance in terms of wear are leading to more and more detailed studies of the cams and rollers. Wear reduction studies for prolonging lifetime of these components require decreasing the scale of observation down to roughness. Among the different wear stages of a component, the running-in is a crucial period which will greatly influence the lifetime and performance of components. The aim of this paper is to analyze the topography variations observed during the running-in of a camshaft on a valve train rig test. A truck engine's camshaft is run under realistic conditions and 3D surfaces are measured before and after the test by using relocation techniques. By measuring the very same surfaces before and after the experiment, a deep analysis of the running-in effects on surfaces can be performed. 3D surface roughness parameters are used in parallel with new proposed methods of analysis. As a result, the mechanisms involved during running-in are emphasized and can be used for further simulations and optimization of the cam roller contact. (C) 2014 Elsevier B.V. All rights reserved.

  • 230.
    Cabanettes, Frédéric
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Alessi, Julien
    Bonomi, T.
    Faure, N.
    Mohlin, Johan
    Finnveden Powertrain, Lidköping, Sweden.
    Rosén, B-G
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Maskinteknisk produktframtagning (MTEK).
    Testing functional surfaces of heavy duty valve train components under realistic operating conditions2012Inngår i: 15th Nordic Symposium on Tribology, 12-15 June 2012, Trondheim, Norway, 2012Konferansepaper (Fagfellevurdert)
  • 231.
    Cabanettes, Frédéric
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Anderberg, Cecilia
    Volvo Cars Corp..
    Dimkovski, Zlate
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Rosén, Bengt-Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Optimizing the Manufacturing of Driveline Surfaces Roughness Parameters and Rough Contact Modeling2009Inngår i: Proceedings of the 12th International Conference on Metrology and Properties of Engineering Surfaces: July 8th - 10th 2009, Rzeszów, Poland / [ed] P. Pawlus, L. Blunt, B.-G. Rosén, T. Thomas, M. Wieczorowski, H. Zahouani, Rzeszòv, Poland: Rzeszow University of Technology , 2009Konferansepaper (Fagfellevurdert)
  • 232.
    Cabanettes, Frédéric
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Claret-Tournier, Julien
    Mohlin, Johan
    Nilsson, Per Henrik
    Rosén, Bengt-Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Xiao, Li
    The evolution of surface topography of injection cams2007Inngår i: Proceedings of the 11th International Conference on Metrology and Properties of Engineering Surfaces: July 17th - 20th 2007, Huddersfield, UK / [ed] Liam Blunt, Huddersfield: Huddersfield University , 2007Konferansepaper (Fagfellevurdert)
  • 233.
    Cabanettes, Frédéric
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Löfgren, Hans Bertil
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Rosén, Bengt-Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Evaluation of manufacturing processes for cam/roller contact2011Konferansepaper (Fagfellevurdert)
  • 234.
    Cabanettes, Frédéric
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Löfgren, Hans Bertil
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Rosén, Bengt-Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    The impact of manufacturing processes on Automotive Cam/Roller Contact2011Konferansepaper (Fagfellevurdert)
  • 235.
    Cabanettes, Frédéric
    et al.
    University of Lyon, ENISE LTDS, Saint-Etienne, France.
    Rolland, Julian
    University of Lyon, ENISE LTDS, Saint-Etienne, France.
    Dumont, Florian
    University of Lyon, ENISE LTDS, Saint-Etienne, France.
    Rech, Joël
    University of Lyon, ENISE LTDS, Saint-Etienne, France.
    Dimkovski, Zlate
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Influence of Minimum Quantity Lubrication on Friction Characterizing Tool–Aluminum Alloy Contact2016Inngår i: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 138, nr 2, artikkel-id 021107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possibility to reduce the amount of cutting fluids from machining processes is actively studied by the industrials and researchers. Minimum Quantity Lubrication (MQL) is a solution towards cutting fluids reduction. This article investigates the consequences on friction coefficient induced by the use of MQL. A tribometer is used in order to simulate experimentally the tribological conditions encountered during machining. As the cutting speed increases a lower amount of oil is deposited on the rough surfaces. Depending on the MQL operating conditions and sliding velocities it is plausible to reach starvation by leaving the real rough contact partly dry. A model computing a starvation percentage by filling an estimated oil amount in a deformed topography correlates with the experimental results. © 2015 by ASME

  • 236.
    Canhasi, Lumi
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Numerical investigation on the effects of out-of-flatness on leakage in metal-to-metal seals2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Since the usage of pressurized systems, there has been a challenge to prevent and control leakage of different fluids. When a metal-to-metal face seal is designed, different aspects are to be considered. Its ring shaped sealing surface is designed to prevent leakage and also to maintain pressure. In this thesis, the main objective is to study how out-of-flatness affects the leakage. This property of sealing interface can be described by different wave parameters and in this case, by means of modelling and numerical simulations. The best approach is the usage of Heterogeneous Multiscale Method (HMM). The data obtained by means of the two-scale stochastic model showed that the pressure amplitude is the most important parameter of the out-of-flatness. In same level of importance, comes the mean pressure even though it is not considered an out-of-flatness parameter. From the data obtained, a simple mathematical expression for leak rate was constructed that shows the effect of out-of-flatness.

  • 237. Carlevi, Jens
    et al.
    Lundmark, Jonas
    Prakash, Braham
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Tribological performance of different functional surfaces of piston and cylinder bore2005Inngår i: Book of Abstracts: International Tribology Conference KOBE / [ed] N. Ohmae; H. Ishigaki, Tokyo: Japan Society of Tribologists , 2005, s. 211-Konferansepaper (Annet vitenskapelig)
  • 238.
    Carlsson, Jenny
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Heldin, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Isaksson, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Wiklund, Urban
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Investigating tool engagement in groundwood pulping: finite element modelling and in-situ observations at the microscaleInngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434XArtikkel i tidsskrift (Fagfellevurdert)
  • 239.
    Casanueva, Carlos
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Doulgerakis, Emmanouil
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Jönsson, Per-Anders
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Stichel, Sebastian
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Influence of switches and crossings on wheel profile evolution in freight vehicles2014Inngår i: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 52, nr SI, s. 317-337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wheel reprofiling costs for freight vehicles are a major issue in Sweden, reducing the profitability of freight traffic operations and therefore hindering the modal shift needed for achieving reduced emissions. In order to understand the damage modes in freight vehicles, uniform wear prediction with Archard's wear law has been studied in a two-axle timber transport wagon, and simulation results have been compared to measurements. Challenges of wheel wear prediction in freight wagons are discussed, including the influence of block brakes and switches and crossings. The latter have a major influence on the profile evolution of this case study, so specific simulations are performed and a thorough discussion is carried out.

  • 240.
    Casanueva, Carlos
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Enblom, Roger
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon. Bombardier Transportation, Swedem.
    Berg, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Comparison of wear prediction models for different contact conditions2016Inngår i: Proceedings of the 24th Symposium of the International Association for Vehicle System Dynamics (IAVSD 2015), Graz, Austria, 17-21 August 2015 / [ed] Martin Rosenberger, Manfred Plöchl, Klaus Six, and Johannes Edelmann, CRC Press, 2016, s. 871-878Konferansepaper (Fagfellevurdert)
    Abstract [en]

     Simulation of wheel and rail wear allows to predict long term profile evolution and thus, study the consequences of wheel damage in the dynamic behaviour of the vehicle, or study future maintenance requirements. Several models have been developed which try to solve the wear issue by relating the energy dissipated in the wheel-rail contact to the worn out material, from which two can be highlighted (Tg/A and Archard) which have significant differences on contact level. Even though, the prediction of long term wheel profile evolution has been validated with these two models, which means that for regular applications they seem to have an equivalent behaviour. In this work similarities and differences between the long term wear prediction methodologies are analysed, discussing their actual limitations. Then, these differences are exploited in specific operational cases to compare their wear prediction performance.

  • 241.
    Casanueva, Carlos
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Jönsson, Per-Anders
    Tikab Strukturmekanik AB.
    Stichel, Sebastian
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    influence of switches and crossings on wheel profile evolution in freight vehicles2013Inngår i: Proceedings of the 23nd IAVSD Symposium on Dynamics of Vehicles on Roads and Tracks / [ed] Simon Iwnicki, Taylor & Francis, 2013Konferansepaper (Fagfellevurdert)
  • 242.
    Casanueva, Carlos
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Jönsson, Per-Anders
    Tikab Strukturmekanik AB.
    Stichel, Sebastian
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
    Use of Archard's wear law for the calculation of uniform wheel wear of high tonnage freight vehicles2013Inngår i: Proceedings of the 1st Joint Rail Conference: JRC2013, ASME Press, 2013, s. JRC2013-2545-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wheel profile evolution has a large influence on track and wheelset related maintenance costs. It influences important parameters such as equivalent conicity or contact point positioning, which will affect the dynamic behavior of the vehicle, in both tangent track and curve negotiation. High axle loads in freight wagons may increase both the wheel wear and the damage caused by vehicles with both new and already worn profiles. A common profile in Europe is the S1002 profile, developed for rail inclination 1/40. In Sweden rail inclination is 1/30, so contact conditions might not be optimal. The presented work uses Archard’s wear law to analyze the profile wear evolution in a two axle freight vehicle with Unitruck running gear on the Swedish network. This wear calculation methodology has been successfully used to predict uniform wear in passenger vehicles. First, the vehicle model has been optimized in order to improve the speed of the wear simulations. Experimental measurements of wheel profiles have been performed in order to validate the simulations. The conclusion is that the wear methodology successfully used to predict uniform wheel wear in passenger vehicles cannot be directly applied for the calculation of wheel profile evolution in high tonnage freight vehicles. The influence of block brakes or switches and crossings cannot be dismissed when calculating uniform wheel wear in these cases.

  • 243.
    Casselgren, Johan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Engström, Niclas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Rosendahl, Sara
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Fransson, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Investigation of ice surface change during vehicle testing2014Inngår i: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, E-ISSN 1745-6444, Vol. 9, nr 2, s. 137-150Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Today, there are a lot of vehicles and tyre testing carried out on lake ice surfaces. Thus, it is important to have knowledge about parameters that affect roadgrip. The thesis within this paper is that the liquid like layer which appears due to increasing temperature can be reduced by manipulating the ice roughness. This in turn should decrease the temperature dependence of the roadgrip in temperatures around 0°C. In order to investigate this, measurements of temperature, surface roughness and hardness and roadgrip were performed on three outdoor ice surfaces using an IR thermometer, an optical sensor with three IR-diodes, a steel ball drop indentation test and an RT3 curve, respectively. Additional ice roughness measurements were also made on two tempered ice surfaces in an ice hall. Results show a clear connection between ice temperature and roadgrip, unfortunately the created ice roughness was too small to influence the change in roadgrip

  • 244.
    Caykara, Tugce
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Self-Lubricating Properties of Laser Claddings for High Temperature Forming Processes2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis summarizes the work done on tribological characterization of multifunctional hardfacing coatings with self-lubricating properties, intended for use in mechanical components operating in high temperature applications for which conventional lubricants are no longer effective. Deposition techniques like laser cladding have a great potential in reworking/repair of high value industrial components in order to extend their lifetime. It is expected that the use of self-lubricating laser claddings could be useful in high temperature applications like metal forming, leading to decreased friction and wear. In this study, the tribological behavior of self-lubricating claddings has been studied against steel and aluminum counter surfaces, using ASI52100 bearing steel in addition to AA6082 and AA2007 aluminum flat pins as the counter bodies. Nickel- and iron-based powders have been chosen for the preparation of claddings. Self-lubricating properties of Ag/MoS2 have been compared to an untreated reference cladding and grade 1.2367 tool steel. For steel counter surfaces, tribological properties in the temperature range between RT and 600⁰C have been investigated and at 300°C for aluminum counter surfaces. Tribological tests were done by a high frequency linear oscillation (SRV) test machine under reciprocating conditions. The wear scar and volume of coatings were measured by using a 3D optical profilometer. SEM/EDS analysis were additionally performed for the characterization of microstructure and wear scar. The results indicated that MoS2 reduced friction and wear of the Fe-based cladding material when tested against steel at room temperature compared to the reference alloy and grade 1.2367 tool steel, and that the addition of silver further decreased wear in addition to early stage friction. It was also observed that the tribolayer, which was formed during the sliding of Ni-based - 5 Ag - 10 MoS2 and against aluminium under lubricated conditions, was protective and provided low and steady friction. 

  • 245.
    Ceron, Ermanno
    et al.
    Technical University of Denmark.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Bay, Niels
    Technical University of Denmark.
    Lubricant film breakdown and material pick-up in sheet forming of advanced high strength steels and stainless steels when using environmental friendly lubricants2014Inngår i: Advanced Materials Research, ISSN 1022-6680, E-ISSN 1662-8985, Vol. 966-967, s. 219-227Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Increasing focus on environmental issues in industrial production has urged sheet metal stamping companies to look for new tribo-systems in order to substitute hazardous lubricants such as chlorinated paraffin oils. The efficiency of chlorinated paraffin is due to the fact that the lubricant reacts chemically with the tool and workpiece material forming thin films, which adhere strongly to the surfaces and reduce the tendency to metal-metal contact and material pick-up. Production tests of new, environmentally benign tribo-systems are, however, costly and laboratory tests are preferred as a preliminary simulative method to investigate alternative tribo-systems. The present paper presents a case study where an industrial process, consisting of deep drawing with two subsequent re-drawings, was selected and four potential new tribo-systems were tested including different workpiece materials, i.e. AHSSs and stainless steels. The performance of the tribo-systems was analyzed in the laboratory by means of a newly developed simulative test as well as in an industrial production process. The results obtained show a good agreement between the laboratory test and the industrial production process regarding the tribological performance, i.e. tendency to material pick-up and galling, of the evaluated tribo-systems. Moreover the SEM analysis shows that different workpiece materials result in different types of material pick-up.

  • 246.
    Cervantes, Michel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Aidanpää, Jan-Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Glavatskih, Sergei
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Karlsson, Thommy
    Interdisciplinary research in full-scale hydropower machines at Porjus, Jokkmokk, Sweden2005Inngår i: International Water Power and Dam Construction, ISSN 0306-400X, E-ISSN 1538-6414, Vol. 57, nr 12, s. 40-44Artikkel i tidsskrift (Annet vitenskapelig)
  • 247.
    Cervantes, Michel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Aidanpää, Jan-Olov
    Glavatskikh, Sergei
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Karlsson, Thommy
    Group dynamics [hydro power equipment]2005Inngår i: International Water Power and Dam Construction, ISSN 0306-400X, E-ISSN 1538-6414, Vol. 57, nr 12, s. 40-45Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    An interdisciplinary research group was created at the Lulea University of Technology in Sweden to help develop world leading competencies and knowledge for cutting-edge technologies in hydro power generation. Based on the studies of this Swedish research group, this paper provides a description of the power system from a dynamic point of view to obtain an overall picture, and is completed with a detailed description of the bearings and turbines. The state-of-the-art in each field is presented, together with suggestions for further development

  • 248.
    Cervantes, Michel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Jansson, Ida
    Jourak, Amir
    Glavatskih, Sergei
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Aidanpää, Jan-Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Porjus U9A full-scale hydropower research facility2008Inngår i: Hydro technology and the evironment for the new century: 24th IAHR Symposium on Hydraulic Machinery and Systems, October 27 - 31, 2008, Foz do Iguassu, Brazil, Foz do Iguassu, 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Hydropower still faces complex scientific and technical challenges in order to secure the availability and reliability of the power plants despite more than a century of development. The main challenge is due to new market constrains such as electrical market deregulation and introduction of renewable sources of energy. The major problem is related to the dynamic of the rotor involving several fields: hydraulics, power engineering and mechanics. On the other side, the large and growing hydropower world market represents an opportunity for technically advanced companies offering better efficiency. The difficulty to scale rigorously any technical advance makes full-scale experiment a necessity. World unique facilities are available at Porjus, Sweden, for this purpose. The Porjus Hydropower Centre is composed of a Francis (U8) and a Kaplan (U9) turbine of 10 MW, each exclusively dedicated to education, research and development. In order to further investigate specific issues related to availability and reliability, a project was initiated in 2006. The main objective is to make U9 a full-scale hydropower laboratory able firstly to furnish the necessary data for the development of rotor-dynamic models but also turbines and bearings. To this purposes more than 200 sensors have been installed to measure displacements, forces, pressure, film thickness, strains... The work presents an overview of the newly upgrade facility as well as some of the problems faced during the instrumentation of the machine.

  • 249.
    Cha, Matthew
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Dynamic Performance and Design Aspects of Compliant Fluid Film Bearings2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Due to government regulations together with health and safety reasons, there are increasing demands on reducing hazardous polluting chemicals from fossil fuel power plants. Therefore, more efforts are imposed on using renewable resources such as water, wind, solar and tide to produce clean/green electricity. On top of that, there is another increasing demand from Original Equipment Manufacturers (OEMs) to operate power plants with higher load while keep the power loss to the minimum. These requirements drive conventional fluid film bearings to its mechanical and temperature limits. This calls for the development of new bearing system designs. An outstanding tribological performance such as low start-up and break-away friction, excellent resistance to chemical attack and anti-seizure properties, can be achieved by introducing compliant polymer liners. At the same time, bearings with compliant liners may alter rotor-bearing system dynamic behaviour compared to the systems with conventional white metal bearings. The research approach of this thesis is to implement compliant liner on bearing surface, impose synchronous shaft excitation and investigate the effect of bearing design parameters on bearing dynamic response.

    Plain cylindrical journal bearings with different compliant liner thicknesses were analysed using a FEM approach. The numerical model was compared with an in-house developed code based on the finite difference method (FDM) for a bearing operated at steady state conditions. Results obtained by the numerical models showed good agreement. After verification of the numerical model for fixed geometry journal bearings, models for tilting pad journal bearings were developed. Dynamic behaviour of the tilting pad journal bearing with three pads with line pivot geometry was compared with published data. A good agreement was obtained between the two numerical models. The effect of pad pivot geometry on bearing dynamic response was investigated. Vertical and horizontal shaft configurations were compared in terms of the effect of preload factor, radial clearance, pivot offset, and pad inclination angles. Influence of the elastic properties of compliant liners was also studied. All these factors significantly affect bearing dynamic response. It is shown how these factors should be selected to control the journal orbit sizes. Misalignments in compliant tilting pad journal bearings were analysed for load between pivots and load on pivots with consideration of thermal effects. Significant improvements in bearing performance were obtained with compliant bearings compared to white metal bearings. Furthermore, different polymer materials (PTFE, UHMWPE, pure PEEK and PEEK composite) were characterized using Frequency Response Function (FRF). It was shown that as the excitation frequency increased the equivalent stiffness was more or less constant while equivalent damping decreased exponentially. PTFE had similar equivalent stiffness compared to PEEK. As for equivalent damping, PTFE had slightly higher damping compared to PEEK or UHMWPE. Oil film thickness, oil film temperature and loads on tilting pad journal bearing were measured on 10 MW Kaplan hydroelectric power machine. Test results were compared to FEM model. It was shown that stiffness of the supporting structure may be more important to machine performance than the stiffness of the bearing alone.

  • 250.
    Cha, Matthew
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Nonlinear Isoviscous Behaviour of Compliant Journal Bearings2012Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Plans to shut down nuclear power plants in some European countries as well as increased electricity production by wind and solar power will increase the work load on hydroelectric power plants in the future. Also, due to the power grid regulations, hydroelectric power plants undergo more frequent start-ups and shut-downs. During such transient periods, a large amplitude shaft motion can occur, especially in the power plants with vertical shafts. Large shaft motion is not desirable because it can lead to a machine failure. Furthermore, performance limitations of conventional white metal or babbitted bearings call for the development of new bearing designs. An outstanding tribological performance can be achieved by introducing compliant polymer liners. At the same time, bearings with compliant liners may alter rotor-bearing system dynamic behaviour compared to the systems with conventional white metal bearings. The research approach of this thesis is to employ nonlinear analysis to provide further understanding of the compliant bearing dynamic response to synchronous shaft excitation.

    Plain cylindrical journal bearings with different compliant liner thicknesses were analysed using a nonlinear approach. The numerical model was verified with an in-house developed code at steady state conditions. Results obtained by the numerical models showed good agreement. After verification of the numerical model for fixed geometry journal bearings, models for tilting pad journal bearings were developed. Results for the tilting pad journal bearing with three pads with line pivot geometry were compared with published data in dynamic conditions. A good agreement was obtained between the two numerical models. The effect of pad pivot geometry on bearing dynamic response was investigated. Vertical and horizontal shaft configurations were compared in terms of the effect of preload factor, pivot offset, tapers and pad inclination angles. Influence of the viscoelastic properties of compliant liners was also studied. All these factors significantly affect bearing dynamic response. It is shown how these factors should be selected to control the journal orbit sizes. It was also shown that the compliant liner provides lower maximum oil film pressure and thicker minimum oil film thickness in the bearing mid-plane in both static and dynamic operating conditions.

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