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  • 101.
    Fredriksson, Gunnel
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Materialutveckling beträffande formningsverktyg för prototyp och småserier1992Report (Other academic)
  • 102.
    Fredriksson, Gunnel
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Metoder för ytjämnhetsmätning1988Report (Other academic)
  • 103.
    Fredriksson, Gunnel
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Hogmark, S.
    Crack Growth in Cold Work Tool Steels - Influence of Surface Condition, Microstructure and Hardness1999Conference paper (Refereed)
  • 104.
    Fredriksson, Gunnel
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Hogmark, S
    Fatigue resistance and surface properties of EDMed cold work tool steels1996Conference paper (Refereed)
  • 105.
    Fredriksson, Gunnel
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Hogmark, S
    Influence of dielectric and temperature in electrical discharge machining of hot work tool steel1996In: Surface Engineering 11Article in journal (Refereed)
  • 106.
    Gaard, Anders
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Influence of tool microstructure on galling resistance2013In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 57, p. 251-256Article in journal (Refereed)
    Abstract [en]

    In sheet metal forming, different types of tool steels are used depending on sheet quality. In the present work, influence of amount, and type, of primary carbides and carbo-nitrides was investigated regarding tool galling resistance against austenitic stainless steel. A significant impact of amount of carbides on galling resistance was observed and tool performance was improved as volume fraction increased. However, no influence of carbide type was distinguished. Alloying by nitrogen further improved the galling resistance and best tool performance was observed for a tool steel comprising only carbo-nitride M(C,N) particles. Besides transfer of sheet material, several other tool damage mechanisms were observed such as cracking, micro-chipping and abrasive scratching. (C) 2012 Elsevier Ltd. All rights reserved.

  • 107.
    Girlanda, Orlando
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Fellers, Christer
    Delamination Position in Multiply Paperboard Acheived by Different Testing MethodsManuscript (preprint) (Other academic)
  • 108.
    Girlanda, Orlando
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Fellers, Christer
    STFI-Packforsk AB, Stockholm.
    Evaluation of the tensile stress-strain properties in the thickness direction of paper materials2007In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, no 1, p. 49-56Article in journal (Refereed)
  • 109.
    Girlanda, Orlando
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Fellers, Christer
    STFI-Packforsk AB, Stockholm.
    Modeling of Delamination in Paperboard during Sheet Offset PrintingManuscript (preprint) (Other academic)
  • 110. Girlanda, Orlando
    et al.
    Hallbäck, Nils
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Östlund, S.
    Tryding, J.
    Defect sensitivity and strength of paperboard in the out-of-plane tension and shear2005In: Journal of Pulp and Paper Science, 31(2), 100-104 (2005)Article in journal (Refereed)
  • 111.
    Gustafsson, Filip
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Wet clutch load modeling for powershift transmission bench tests.2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis a model is developed for calculating the loads on the wetclutches in apowershift transmission. This thesis was done at Volvo CE in Eskilstuna and is focusedon their 4-speed countershaft transmissions. The goal of the project is to be able tocalculate the loads automatically during the transmission tests and thus acquire increasedknowledge about what occurs during operation.The model was developed by first generating a number of concepts and then evalu-ating them to decide which one should be developed further. The chosen concept wasthen developed further and implemented into the test equipment as a calculation script.The chosen loads to model were the energy absorbed in each clutch, the coefficient offriction (COF) and the slip distance. The COF was later found to give too unreliableresults to be used in any other way than as a benchmark for how well the model wasconfigured and to see any large changes in COF.The model was validated by calculating the energy absorbed in a HTE-200 seriestransmission and comparing it to a reference calculation model. It was seen that theresults from the new model are very close to the reference result. The energy lostcalculated by the new model will be equal to 94 % of the energy lost calculated by thereference model, but only when measuring the inertia phase. The energy lost is equalto 135 % when the torque phase is included. The increasing difference is believed tobe because of an error in the reference model that means it does not cover the torquephase.

  • 112.
    Gustafsson, Johan
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Från order till montering hos AP&T: En studie om förbättringsarbete2013Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This study is performed at AP&T AB in Blidsberg. They mostly build automated production lines and tools for presses. They want to have their supply chain charted. With this mapping it is possible to find deviations that stop the flow of information and material. This work will be limited to two of the company’s suppliers. The flow will end in assembly.

    To make the mapping two methods was used, functional flow chart and process analysis sched- ule. The first method will show which activities occur in each department. The second will show how much time or cost an activity demands. With this it is possible to in the end of work to analysis if the new way to work give a better result. When the mapping was done and the deviations found the study continued to sort them in a PICK-chart. This method compares the workload to the effects of improvements in each deviation. This was implemented with workers during the study to get their opinion.

    To create an improvement the method PDCA was used. This method was not used the whole way. That is because this study has a limited time frame of twenty weeks. Only a plan of action was produced with this method.

    This study will pay attention to how important it is to have the right quality of material and information. If it is wrong it created more wastage in the end of the process. It is important that each department is well informed and aware before material and information is forwarded in the production chain. If the conditions are visible in a early stage its easier to ensure the proper quality. This study has made a deeper analyse in two deviations.

    One deviation could be clear to be a result of not complete drawings that have been forwarded to suppliers. Why that had happened was because the constructions phase has not been reviewed. That even tough according to ISO 9000:2008 drawings should be review and be ensured they meet the required criteria.

    In stock it is a problem with the packing of the material to the machine. It is missing structure and procedures and that results in problem for the assemblers because it is hard to get knowl- edge about witch material exists.

    To enhance visibility of this requires an interconnection between departments. It would in this case be able to involve every department by having a representative to meet and discuss the problems and the improvement list that AP & T established. Lifting up the problems and find the root cause. If all understands the problem, it is easier to understand what it is that is wrong.

    The conclusion to be drawn is that it requires knowledge of what is right, to leave right basis. As well it’s need for measurements that provide ratios that decisions can be based on to get an un- derstanding and motivation among employees about why an improvement to be implemented.

  • 113.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Galling in sheet metal forming2008In: Proceedings of the IDDRG 2008 Conference : Best in class stamping, 16-18 June 2008, Olofström, Sweden., 2008Conference paper (Refereed)
  • 114.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Galling resistance of cold work tool materials in sliding against carbon steel2007In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 26, no 1, p. 67-72Article in journal (Refereed)
  • 115.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Tribology in sheet metal forming: a literature reviewManuscript (Other academic)
  • 116.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Wear in sheet metal forming2008Licentiate thesis, monograph (Other academic)
  • 117.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Wear in sheet metal forming2008Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The general trend in the car body manufacturing industry is towards low-series production and reduction of press lubricants and car weight. The limited use of press lubricants, in combination with the introduction of high and ultra-high strength sheet materials, continuously increases the demands of the forming tools. To provide the means of forming new generations of sheet material, development of new tool materials with improved galling resistance is required, which may include tailored microstructures, introducing of specific(MC, M(C,N))carbides and nitrides, coatings and improved surface finish. In the present work, the wear mechanisms in real forming operations have been studied and emulated on a laboratory scale by developing a test equipment. The wear mechanisms identified in the real forming process, were distinguished into a sequence of events consisting of initial local adhesive wear of the sheets resulting in transfer of sheet material to the tool surfaces. Successive forming operations led to growth of the transfer layer and initiation of scratching of the sheets. Finally, scratching changed into severe adhesive wear, associated with gross macroscopic damage. The wear process was repeated in the laboratory test-equipment in sliding between several tool materials, ranging from cast iron to conventional ingot cast tool steels to advanced powder metallurgy tool steel, against dual-phase carbon steel sheets. By use of the test-equipment, selected tool materials were ranked regarding wear resistance in sliding against ferritic-martensitic steel sheets at different contact pressures.

    Wear in sheet metal forming is mainly determined by adhesion; initially between the tool and sheet surface interaction and subsequently, after initiation of material transfer, between a sheet to sheet contact. Atomic force microscopy force curves showed that adhesion is sensitive to both chemical composition and temperature. By alloying of iron with 18wt.% Cr and 8wt.% Ni, alloying in itself, or changes in crystal structure, led to an increase of 3 times in adhesion at room temperature. Hence, alloying may be assumed a promising way for control of adhesive properties. Additionally, frictional heating should be controlled to avoid high adhesion as, generally, adhesion was found to increase with increasing temperature for all investigated materials.

  • 118.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Wear mechanisms in sheet metal forming: Effects of tool microstructure, adhesion and temperature2008Doctoral thesis, monograph (Other academic)
  • 119.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Wear mechanisms in sheet metal forming: Effects of tool microstructure, adhesion and temperature2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The general trend in the car body manufacturing industry is towards low-series production and reduction of press lubricants and car weight. The limited use of lubricants, in combination with the introduction of high and ultrahigh-strength sheet materials, continuously increases the demands on the forming tools. The major cause for tool failure during the forming process is transfer and accumulation of sheet material on the tool surfaces, generally referred to as galling. The adhered material creates unstable frictional conditions and scratching of the tool/sheet interface. To provide the means of forming new generations of sheet materials, development of new tool materialswith improved galling resistance is required, which may include tailored microstructures introducing specific carbides and nitrides, coatings and improved surface finish. In the present work, the galling wear mechanisms in real forming operations have been studied and emulated at a laboratory scale by developing a test equipment. The wear mechanisms, identified in the real forming process, were distinguished into a sequence of events. At the initial stage, local adhesive wear of the sheets led to transfer of sheet material to the tool surfaces. Successive forming operations resulted in growth of the transfer layer with initiation of scratching of the sheets. Finally, scratching changed into severe adhesive wear, associated withgross macroscopic damage. The wear process was successfully repeated in the laboratory test equipment in sliding between several tool materials, ranging from cast iron and conventional ingot cast tool steels, to advanced powder metallurgy tool steel, sliding against medium and high-strength steel sheets. By use of the test equipment, selected tool materials were ranked regarding galling resistance. The controlling mechanism for galling in sheet metal forming is adhesion. The initial sheet material transfer was found to occur, preferably, to the metallic matrix of the tool steels. Hence, the carbides in the particular steels appeared less prone to adhesion as compared to the metallic matrix. Therefore, an improved galling resistance was observed for a tool steel comprising a high amount of small homogeneously distributed carbides offering a low-strength interface to the transferred sheet material.Further, atomic force microscopy showed that nanoscale adhesion was influenced by temperature, with increasing adhesion as temperature increases. A similar dependence was observed at the macroscale where increasing surface temperature led to initiation of severe adhesive wear. The results were in good agreement to the nano scale observations and temperature-induced high adhesion was suggested as a possible mechanism.

  • 120.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Wear of tools sliding against carbon steel sheets2006Conference paper (Refereed)
  • 121.
    Gåård, Anders
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Hallbäck, Nils
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Temperature effects on adhesive wear in dry sliding contacts2010In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 268, no 7-8, p. 968-975Article in journal (Refereed)
  • 122.
    Gåård, Anders
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Hirvonen Grytzelius, Joakim
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Zhang, Hanmin
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Experimental study of the relationship between temperature and adhesive forces for low-alloyed steel, stainless steel and titanium using atomic force microscopy in ultra-high vacuum2008In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, ISSN 0021-8979, Vol. 103, no 12, article id 124301Article in journal (Refereed)
  • 123.
    Gåård, Anders
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Influence of tool steel microstructure on origin of galling initiation and wear mechanisms under dry sliding against carbon steel sheets2009In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 267, no 1-4, p. 387-393Article in journal (Refereed)
  • 124.
    Gåård, Anders
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Microstructural characterization and wear behavior of (Fe,Ni)-TiC MMC prepared by DMLS2006In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 421, no 1-2, p. 166-171Article in journal (Refereed)
  • 125.
    Gåård, Anders
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Wear mechanisms in deep drawing of carbon steel: correlation to laboratory testing2008In: Tribotest, ISSN 1354-4063, Vol. 14, no 1, p. 1-9Article in journal (Refereed)
  • 126.
    Gåård, Anders
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Wear mechanisms in galling: cold work tool materials sliding against high-strength carbon steel sheets2009In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 33, no 1, p. 45-53Article in journal (Other academic)
    Abstract [en]

    Transfer and accumulation of adhered sheet material, generally referred to as galling, is the major cause for tool failure in sheet metal forming. In this study, the galling resistances of several tool steels were evaluated against dual-phase high-strength carbon steel using a SOFS tribometer, in which disc-shaped tools were slid against a real sheet surface in dry sliding test conditions. Three different frictional regimes were identified and characterized during sliding, and any transition in friction corresponded to a transition in wear mechanisms of the sheets. The performance of the tools depended on load, material and the particular frictional regime. Best overall performance was obtained by nitrogen-alloyed powder metallurgy tool steel.

  • 127.
    Gåård, Anders
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Hallbäck, Nils
    Karlstad University, Faculty of Technology and Science.
    Galling resistance and wear mechanisms - cold work tool materials sliding against carbon steel sheets2007In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 26, no 1, p. 67-72Article in journal (Refereed)
  • 128.
    Gåård, Anders
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Sarih, Rahim M.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Influence of Tool Material and Surface Roughness on Galling Resistance in Sliding Against Austenitic Stainless Steel2012In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 46, no 2, p. 179-185Article in journal (Refereed)
    Abstract [en]

    Transfer and accumulation of adhered sheet material, generally referred to as galling, is a major cause for tool failure in sheet metal forming. In the present work, the galling resistance of three different tool materials was evaluated in lubricated sliding against austenitic stainless steel using a SOFS tribometer. All tool materials were prepared to four different surface roughnesses, ranging from a polished surface with R (a) = 0.05 mu m to a ground surface with R (a) = 0.3 mu m. The overall best performance was obtained for polished nitrogen alloyed powder metallurgy (PM) tool steel, where galling was detected only at the highest load evaluated, 700 N. However, for both the D2 type tool steel and nodular iron, best performance was observed for the surface possessing a surface roughness of 0.1 mu m. The improved galling resistance for the rougher surfaces was related to filling of grinding scratches with sheet material during the initial stage of sliding, prolonging the development of protruding sheet material on the tools surface. Similar trend was not observed for the PM steel, which was related to width of the scratches originating from the surface preparation, in relation to tool microstructure.

  • 129.
    Haglund, Oskar
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Metod och verifiering för mätning av stora diametrar2017Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Syftet med detta projekt har varit att få fram hur dagens mätmetod på Valmet AB i Karlstad står sig jämfört med en eller flera andra mätmetoder. Samt att se vilka faktorer som påverkar dagens mätning mest. Mätmetoderna har varit för mätning av stora ytterdiametrar mellan 1500-1970mm.

     

    Målet med projektet har varit att göra en undersökning och analys av dagens mätmetod samt analyser på en eller flera mätmetoder som kan appliceras hos Valmet. Dessa mätmetoder ska utvärderas mot dagens mätmetod.

     

    Mätserier utfördes på dagens mätmetod som är Pi Tape. Genom dessa mätserier kunde flera viktiga mått tas fram. Dessa mått var standardavvikelse, mätosäkerhet, repeterbarhet och reproducerbarhet. Med hjälp av databaser med temperaturloggning i maskinverkstaden kunde temperaturskillnader över tid tas fram. Samma mätserier gjordes sedan på en ny mätmetod som Valmet funderat på, denna metod var en mätbygel med en mätklocka som mäter avvikelser från en normal med givet mått. Det byggdes en prototyp som sedan testades.

     

    Mätmetoderna som testades fick väldigt lika resultat, där det tydligt syns att mätmetoderna i sig är väldigt bra. Med snäva toleranser ger temperaturavvikelser betydlig påverkan på utvidgningen av materialet. Genom dessa resultat togs vissa åtgärder fram som Valmet kan använda sig av. 

  • 130. Hallberg Hofstrand, Erik
    et al.
    Lestelius, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science.
    Rättö, Peter
    Thuvander, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Odeberg Glasenapp, A.
    Evaluation of Pressure Variations Generated During Flexographic Post-Print of Corrugated Board and Effects of Mechanical Properties of Printing Forms on Printed Banding2004Conference paper (Other (popular science, discussion, etc.))
  • 131. Hallberg Hofstrand, Erik
    et al.
    Lestelius, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science.
    Rättö, Peter
    Thuvander, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Odeberg Glasenapp, A
    Flexo Print of Corrugated Board: Mechanical Aspects of the Plate and Plate Mounting Materials2005In: TAGA Journal, vol.2,pp.16-28Article in journal (Refereed)
  • 132.
    Hallbäck, Nils
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Girlanda, Orlando
    Tryding, J
    Finite element Analysis of Ink-Tack Delamination of Paperboard2006In: International Journal of Solids and Structures, 43(5), 899–912 (2006)Article in journal (Refereed)
  • 133.
    Hallbäck, Nils
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Korin, Christer
    Karlstad University, Faculty of Technology and Science, Paper Surface Centre.
    Vähä-Nissi, Mika
    Seppänen, Rauni
    Laine, Christiane
    Influence of paperboard on bond formation and strength of adhesive joint2009Conference paper (Refereed)
    Abstract

    Knowledge about the glueability of fiber-based materials is limited. Factors affecting the adhesive joint between adhesive and paperboard are presented here through two cases: strength of hot melt adhesive joint and consolidation of dispersion adhesive. The hot melt joint was investigated by Y-peel testing, while shear testing was applied for dispersion adhesives. A set of supplementing tools was used to understand the adhesive joints, their development and failure. The results show, for example, the importance of paperboard roughness on the hot melt joint strength. Formation of an adhesive joint with dispersion adhesives is affected by the rheological properties of the adhesive layer and the structure and absorbation properties of the board surface. Both case studies indicate that it can actually be better to apply the adhesive first on a rough surface and the press the smooth surface on the adhesive, which is in contrast with the common practice today

  • 134.
    Hanson, Magnus
    et al.
    Department of Materials Science, Uppsala University.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Hogmark, Sture
    Department of Materials Science, Uppsala University.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Comparison of two test methods for evaluation of forming tool materials2008In: Tribotest, ISSN 1354-4063, Vol. 14, no 2, p. 147-158Article in journal (Refereed)
  • 135.
    Hedberg-Häger, Torleif
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Vidareutveckling av säkring/pipväljare för tvåpipigt gevär2013Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Product developement of a safety and barrel selector mechanism in a two barreled shotgun, in which there are specifications regarding both user experience and functionality.Studies were done on existing solutions and a number of concepts were generated.During the course of the work the questions that needed answering changed when states of the development process were reached that needed new input. The first steps of the work were focusing on ease of manufacturing. The second step was to identify what the market may perceive as exclusive enough in the high segment that the product is marketed against. The two goals were reached separately and concepts satisfying the demands were presented.

  • 136.
    Hellberg, Max
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Optimization of diagonal stiffeners to handle wind pressures on silos2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this report the focus is set on how to optimize the support structure of a silo and in particular, the stiffeners and fastener. The main force of the silo comes from the wind pressures. The design is subjected to the Swedish and European standards SS-EN 199-1-4:2005, 1993-1-1:2005 and 1990. Much of the design work was put on determining the pressure for buckling of the stiffener and to determine the shear force on the bolts. Calculations on how the silo was affected by wind pressure was also calculated by the use of the SS-EN standard. The silo that is analyzed started with a design that was largely conservative designed, which is making it hard for the company constructing the silo to compete on the European market. The focus of the report is to minimize the material needed for the diagonal stiffeners between the columns. This because the diagonal stiffeners made up 80\% of the total stiffener length. The idea is to change the U-shaped beams with the dimensions 50x30x2 to L-shaped beams with the dimensions 25x25x2. A plate that earlier connected the stiffeners was removed and replaced with a circular plate that were put at the place where the diagonal stiffeners intersected each other. This was possible since the stiffeners were put in a configuration where they would not hit each other but instead go past one another. The new ring was placed in the gap between the stiffener. The simulation in Abaqus was performed with the following wind pressures:\\1. Roof: 0,78 MPa.\\2. Shell: 0,5 MPa.\\3. Columns: 0,8 MPa.\\The allowed limiting pressures on the stiffener based on the wind pressures were:\\1. Allowed pressure around bolt: 692 MPa.\\2. Allowed pressure to prevent buckling: 183 MPa.\\3. Allowed pulling pressure on stiffener: 273,6 MPa. \\By color scale it could be determined that the silo would remain stable. The areas that exceeded the allowed values in Abaqus were considered singularities and could be neglected.

    From a manufacturing point of view, the proposed change was possible if two machine tools were used. One for the original stiffeners and one for the changed diagonal stiffener. All changes follows the European standard and resulted in a 24\% cost reduction when counting in the cost of all the stiffeners. The optimized diagonal L-shaped stiffeners has resulted in a decrease in price by 36,3\% while the unchanged stiffeners have increased in price by 26,1\% due to the adding of an additional machine.

  • 137. Hjertsén, D
    et al.
    Sjöström, Johnny
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Näsström, M
    Finite element simulation of tool steel stress response as used in hot forging2004Conference paper (Refereed)
  • 138.
    Holm, Magnus
    et al.
    Högskolan i Skövde.
    Doverborn, Josefin
    Högskolan i Skövde.
    Ng, Amos
    Högskolan i Skövde.
    De Vin, Leo
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Optimisation of Operation Sequences in Flexible Manufacturing Cells Using Virtual Manufacturing Tools2009In: FAIM 2009 Proceedings of the 19 th International Conference on Flexible Automation and Intelligent Manufacturing / [ed] Nabhani, Farhad, Middlesbrough: University of Teesside , 2009, p. 1317-1324Conference paper (Refereed)
  • 139.
    Holmén, Andreas
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Konceptrealisering av tappvarmvattenproducerande sol- och luftvärmepump: Framtagning av funktionsprototyp med syftet att tilltala investerare eller samarbetspartner2012Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This project has been a degree project for the Bachelor of Science programme in Innovation and Design at Karlstad University. The degree project extends 22, 5 ECTS credits and has been carried out by Andreas Holmén. The academic supervisor from Karlstad University was industrial designer and lecturer Lennart Wihk and the examiner was Professor Fredrik Thuvander.

    The degree project was part of a bigger project involving five other students. The project was an industrial cooperation between Karlstad University, Glava energy center and Värmestugan AB.

    The project is built around an idea about being able to improve the energy efficiency of the heating of domestic water by combining solar heating and heat pump technology. The initial phase of the project was carried out with the whole project group together, when the group agreed on a main concept each member of the group focused on his/her specific task.

    This specific degree project set out to find out the requirements suitable for a functional prototype meant to accost an investor or a partner company. But also in what way these requirements could be reached within the project’s timeframe.

    The task was solved by making a research that was compiled by using a functional analysis and a semantic analysis resulting in a requirement specification. Later the information that emerged through the research was used to come up with ideas and design documents for the prototype.

    The construction of the prototype took up the largest part of this project, since it was the group’s main objective to produce a functional prototype within the projects timeframe.

    The final result of this project was the functional prototype of a air-air heat pump aided by the sun, but also the knowledge that was accumulated during the research phase and the making of the prototype.

  • 140.
    Irshad, Muhammad Aatif
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    The effect of prior austenite grain size on the machinability of a pre-hardened mold steel.: Measurement of average grain size using experimental methods and empirical models.2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The use of pre-hardened mold steels has increased appreciably over the years; more than 80% of the plastic mold steels are used in pre-hardened condition. These steels are delivered to the customer in finished state i.e. there is no need of any post treatment. With hardness around ~40HRC, they have properties such as good polishability, good weldability, corrosion resistance and thermal conductivity. Machinability is a very important parameter in pre-hardened mold steels as it has a direct impact on the cost of the mold. In normal machining operations involving intricate or near net shapes, machining constitutes around 60% of the total mold cost.

    Efforts are underway to explore every possible way to reduce costs associated with machining and to make production more economical. All the possible parameters which are considered to affect the machinability are being investigated by the researchers. This thesis work focuses on the effect of prior austenite grain size on the machinability of pre-hardened mold steel (Uddeholm Nimax).

     Austenitizing temperatures and holding times were varied to obtain varying grain sized microstructures in different samples of the same material. As it was difficult to delineate prior-austenite grain boundaries, experimental and empirical methods were employed to obtain reference values. These different grain sized samples were thereafter subjected to machining tests, using two sets of cutting parameters. Maximum flank wear depth=0.2mm was defined for one series of test which were more akin to rough machining, and machining length of 43200mm or maximum wear depth=0.2mm were defined for second series of tests which were similar to finishing machining.

    The results were obtained after careful quantative and qualitative analysis of cutting tools. The results obtained for Uddeholm Nimax seemed to indicate that larger grain sized material was easier to machine. However, factors such as retained austenite content and work hardening on machined surface, which lead to degradation of machining operations were also taken into consideration. Uddeholm Nimax showed better machinability in large grained samples as retained austenite(less than 2%) content was minimal in the large grained sample. Small grained sample in Uddeholm Nimax had a higher retained austenite (7+2%) which resulted in degradation of machining operation and a lesser cutting tool life.

  • 141.
    Jackman, Henrik
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Bending modulus of freestanding carbon nanotubes2010Conference paper (Other academic)
  • 142.
    Jackman, Henrik
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Direct Measurements Of Bending Stiffness And Rippling Phenomena In Free-Standing Carbon Nanotubes2011Conference paper (Refereed)
  • 143.
    Jackman, Henrik
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    High resolution SEM imaging of carbon nanotubes: deconvolution and retrieval of intrinsic nanotube dimensions2012Conference paper (Refereed)
    Abstract [en]

    Characterizing physical properties of individual nanotubes is crucial for their implementation in nano electromechanical systems (NEMS). This requires measurements on suspended or free-standing structures together with accurate determination of the nanotubes dimensions. In situ methods are often used where physical measurements are performed inside electron microscopes [1-3]. Transmission electron microscopy (TEM) has the advantage of high resolution, providing accurate determination of both dimensions and the internal structure. The space inside a TEM is however rather restricted, leaving limited room for additional probes [4]. Scanning electron microscopy (SEM) on the other hand, has a large specimen chamber which facilitates the addition of probes, but the image resolution is lower, making the evaluation of material properties less accurate or even impossible for very thin nanotubes [1]. One way to solve this is to first measure the physical properties inside an SEM, and then determine the diameter using a TEM afterwards [1]. This approach requires transfer of the nanotube from the SEM to a suitable TEM sample holder, and analysis of the same sample-location in both instruments. It would thereby be advantageous to obtain accurate structural information directly inside the SEM [2]. We have studied the mechanisms involved in SEM image formation of small multiwalled nanotubes, 2-5 nm in diameter. The electron-probe shape in an SEM broadens the sample details, and the image can be seen as a convolution of the secondary electron yield at each sample position and the probe shape. By comparing SEM and TEM images, we found that the probe intensity profile was best described by a linear combination of Gaussian and Lorentzian distributions. Using the obtained probe shape, the SEM images could then be deconvoluted to reveal more details, including the inner diameter in some cases. We also show how the outer diameter can be obtained by differentiating image profiles, a method that does not require any detailed knowledge regarding the probe shape and is reliable down to dimensions comparable to the electron-probe size. This significantly improves the capabilities of in-situ SEM experiments by enabling accurate characterizations of nanofibres inside SEM instruments, without the need for subsequent TEM imaging

  • 144.
    Jackman, Henrik
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Image formation mechanisms in scanning electron microscopy of carbon nanotubes,and retrieval of their intrinsic dimensions.2013In: Ultramicroscopy, ISSN 0304-3991, Vol. 124, p. 35-39Article in journal (Refereed)
    Abstract [en]

    We present a detailed analysis of the image formation mechanisms that are involved in the imaging of carbon nanotubes with scanning electron microscopy (SEM). We show how SEM images can be modelled by accounting for surface enhancement effects together with the absorption coefficient for secondary electrons, and the electron-probe shape. Images can then be deconvoluted, enabling retrieval of the intrinsic nanotube dimensions. Accurate estimates of their dimensions can thereby be obtained even for structures that are comparable to the electron-probe size (on the order of 2 nm). We also present a simple and robust model for obtaining the outer diameter of nanotubes without any detailed knowledge about the electron-probe shape.

  • 145.
    Jackman, Henrik
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Large variations in the onset of rippling in concentric nanotubes.2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 104, article id 021910Article in journal (Refereed)
    Abstract [en]

    We present a detailed experimental study of the onset of rippling in highly crystalline carbon nanotubes. Modeling has shown that there should be a material constant, called the critical length, describing the dependence of the critical strain on the nanotube outer radius. Surprisingly, we have found very large variations, by a factor of three, in the critical length. We attribute this to a supporting effect from the inner walls in multiwalled concentric nanotubes. We provide an analytical expression for the maximum deflection prior to rippling, which is an important design consideration in nanoelectromechanical systems utilizing nanotubes.

  • 146.
    Janebrink, Niklas
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Construction of tilt table with high loads: A construction with complete hydraulic system2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    At Uddeholm AB, they today use two overhead cranes with chains to move and tilt steel sheets for visual inspection of surface defects. The tilting is done to give the operator a better view of these defects using reflection of light. The problem with this approach is that it is combined with danger of life with hanging load, in case a chain breaks. Therefore Uddeholm AB would like to develop a tilt table that can be mounted on their lift table they use today.

    To solve this problem, 5 concepts was developed using a product development process. The chosen concept was further developed into a product that met the defined load case to tilt the sheets, weighing up to 20 tonnes, 55 degrees. The design that was selected use two points of rotation and is driven by three hydraulic cylinders.

    The structure has been calculated by hand and with the structural mechanics software Ansys. To tilt the table a complete hydraulic system was developed and dimensioned. The hydraulic system has been calculated by hand and simulated by a computer program called Hopsan developed at Linköping University. 

  • 147. Jansson, A
    et al.
    Thuvander, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Influence of thickness on the mechanical properties for starch films2004In: Carbohydrate Polymers, 56, 499-503, (2004)Article in journal (Refereed)
  • 148.
    Jansson, Adam
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Master thesis within light warhead for support weapon: Investigation of defects, methods and requirement specifications in order to get a shell body shatter free2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    At launching the shell body, especially the backplane of the shell body, will be exposed to very high stresses due to acceleration, pressure and increased temperature from the propellant combustion. Defects in the shell body could in worst case for example result in high temperature gas leakage into the warhead and thereby ignite the explosives before exiting the launcher. This kind of explosion results in serious damages and can seriously injure both the gunner and other people in the surroundings.

    According to earlier study, carbon fibre reinforced epoxy with filament winding manufacturing method was the primary focus. The purpose of this master thesis was to investigate requirements and testing methods on a shell body manufactured in composite that will guarantee the safety of the gunner and surroundings in the launch phase.

    The pre-study conducted in this project showed that matrix cracks and fibre breakages are most common defects in the shell body that occur during launching affected by burst pressure. Matrix crack is the less dangerous defect among the impact damage types. Discussion with composite manufacturing companies showed that fibre breakage is a very serious type of defect since more breakage of fibres leads to the shell body have reduced stresses and cannot built-up the fully potential burst pressure during launching.

     

    Two requirement specifications were carried out, one for the shell body and another for the detection methods. These were created by own research and ideas according to found information, telephone- and e-mail contact with experts in areas and with personnel at Saab Dynamics AB.

    Some requirements for the shell body were that it should be fully usable after drop tests from different heights, vibration and transportation tests yield no cyclic damage after a long transport. Furthermore, the shell body should always use a fully isolated driving band to not have hot explosive gases penetrated into critical sections which results in detonation already in the launcher barrel. The most important requirements for the detection methods were to have depth analysis, high reliability and in-field inspection.

     

    Elimination- and decision matrices were made to find which detection methods should be the final selections in order to find the defects in a shell body. The detection methods which did not fulfil the criteria from each separate matrix were eliminated and did not proceed further as a concept. Eliminations were performed in concept generation phase (elimination matrix) and concept selection phase (decision matrix). In final selection phase a couple of methods were chosen that together found as many defects as possible.

     

    By using both acoustic emission and shearography all the critical defects and a wide range of other defects can be detected with very high reliability and resolution at an acceptable cost. These two methods “interact” perfectly with each other. Acoustic emission is the best method to find fibre breakage and matrix cracks, which are the most commonly occurring defects during launching. But shearography does not have a good detectability of fibre breakage and matrix cracks. On the other hand, shearography has good detectability of both planar- and volumetric defects.

    It is concluded that only two inspection methods, i.e. acoustic emission and shearography are needed to detect all of the possible defects in the grenade shell body. This is more economical solution requiring smaller space and fewer operators compared to one separate NDT method for detecting each type of defect.

  • 149. Jansson, Agneta
    et al.
    Järnström, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Rättö, Peter
    Thuvander, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Physical and Swelling Properties of Spray-Dried Powders made from Starch and Poly(vinyl alcohol)2006In: Starch/Stärke, 58 (12), 632-641,(2006)Article in journal (Refereed)
  • 150. Jansson, Agneta
    et al.
    Thuvander, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Influence of thickness on the mechanical properties for starch films2004In: Carbohydrate Polymers, 56, 2004, pp 499-503Article in journal (Refereed)
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