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  • 201.
    Korin, Christer
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre.
    Hallbäck, Nils
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Junghans, R
    Failure Modes of Adhesively Joined Carton Board2008In: Journal of Adhesion Science and Technology, 2008Article in journal (Refereed)
  • 202.
    Korin, Christer
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Hallbäck, Nils
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Junghans, Robert
    Failure Modes of Adhesive Joints in Carton Board2008In: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 22, p. 2079-2104Article in journal (Refereed)
  • 203.
    Korin, Christer
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre.
    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.
    Tryding, J
    Hallbäck, Nils
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Y-peel Characterization of Adhessively-bonded Carton Board an objective Method2007In: Journal of Adhesion Science and Technology 21 2007 (2) 197-210Article in journal (Refereed)
  • 204.
    Korin, Christer
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Seppänen, Rauni
    YKI, Institute for Surface Chemistry.
    Vähä-Nissi, Miki
    VTT Technical Research Centre of Finland.
    Hallbäck, Nils
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Influence of surface treatments on the mechanical strength of hotmelt adhesive joints made of cartonboards2012In: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 26, no 20-21, p. 2339-2356Article in journal (Refereed)
    Abstract [en]

    The influence of surface treatments including pigment coating, surface sizing and calendering on the mechanical strength of hotmelt adhesive joints in pilot made cartonboards was studied. The mechanical strength of the joints was investigated using the Y-peel test device at 23 degrees C and 50% relative humidity. Some of the samples were investigated with respect to the failure mode by scanning electron microscopy. The surfaces were characterized in terms of surface roughness, surface chemical composition, and adhesion behaviour. A strong adhesive bond displayed fibre tear. In addition to fibre tear, interfacial failure, i.e., failure between the cartonboard and the adhesive, was the main reason for fracture in the bonded assembly. The most important factor controlling the integrity of adhesive joints seemed to be the real contact area. The adhesive joints showed significantly higher strength when the hotmelt adhesive was first applied onto the rougher cartonboard of the assembly and then the smoother cartonboard was pressed on the adhesive than vice versa. The surface roughness of cartonboards mainly depended on whether the surface was pigment coated or not. Calendering displayed only a minor effect. No clear influence of surface chemical composition of the cartonboards on the adhesive joint strength was found due to the fact that changes in surface chemistry in this study also led to changes in surface roughness. The strongest adhesive joint was created between two medium-rough and surface-sized cartonboards.

  • 205. Kotik, Ouliana
    et al.
    Ljungqvist, Carl-Henrik
    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.
    Effect of the strain to failure distribution of pulp fibres on tensile strength of paper2005In: Appita J., 58(4) pp. 288 –292 (2005)Article in journal (Refereed)
  • 206. Kotik, Ouliana
    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.
    Modeling offibre bridging in delamination of board2004Conference paper (Refereed)
  • 207. Kotik, Ouliana
    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.
    Simulation of Paper Failure ' a Micromechanical Model for Localization of the Fracture Process Zone2005In: Appita J., 58(6) pp. 459–461, 469 (2005)Article in journal (Refereed)
  • 208. Kotik, Ouliana
    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.
    Strain to failure properties of pulp and the influence on the mechanical behaviour of paper2002Other (Other (popular science, discussion, etc.))
  • 209. Kotik, Ouliana
    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.
    Ljungqvist, Carl-Henrik
    The strain to failure properties of pulp fibres and its influence on the fracture zone - michromechanical approach2003Other (Other (popular science, discussion, etc.))
  • 210.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Effect of microstructure on edge wear mechanisms in WC-Co, WOM 20072007Conference paper (Refereed)
  • 211.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Energy input effect on the microstructure, morphology and stability of single track in selective laser melting2012Conference paper (Refereed)
  • 212.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Isothermal grain growth in mechanically alloyed nanostructured Fe80Ti8B12 alloy2003In: Materials Letters, ISSN ISSN: 0167-577X, Vol. 57, no 22/23, p. 3671-3675Article in journal (Refereed)
    Abstract [en]

    Isothermalgraingrowth in a mechanicallyalloyednanostructured Fe80Ti8B12alloy was investigated at 915–985 K by TEM and XRD methods. Crystallization of the amorphous phase and grain coarsening stages were observed, and each stage was analyzed using models of a graingrowth with dragging of grain boundaries and of normal graingrowth, respectively. Activation energies were calculated to be 300±10 and 280±10 kJ/mol using the models.

  • 213.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    On the abrasion of ultrafine WC-Co by fine abrasive particles2007In: Transactions of Nonferrous Metals Society of China, ISSN 1003-6326, E-ISSN 2210-3384, Vol. 17, no 6, p. 1287-1293Article in journal (Refereed)
  • 214.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    On the abrasion of ultrafine WC-Co hardmetals by small SiC abrasive2008In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 30, no 1, p. 35-39Article in journal (Refereed)
  • 215.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Preparation of Mo(Si,Al)2-ZrO2 nanocomposite powders by mechanical alloying, International Journal of Refractory Metals and Hard Materials, Volume 22, Issues 4-5, July-September 2004, Pages 205-2092004Article in journal (Refereed)
  • 216.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Tool materials and applications, research experience at KaU, Swedish-Egyptian workshop2007In: Swedish-Egyptian Workshop 2007 (representation of Karlstad University), Cairo, Egypt, SMRDI, 14-16 May 2007Article in journal (Other academic)
  • 217.
    Krakhmalev, Pavel
    et al.
    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.
    Hot wear of Mo(Si,Al)2-base composites sliding against an aluminum alloy, NORDTRIB 20042004In: NORDTRIB 2004, Proceeding of the 11-th Nordic Symposium on Tribology: Tromsø, Harstad, Hurtigruten, [Bodø], Norway, June [1 - 5], 2004, Tromsö, 2004, p. 307-317Conference paper (Refereed)
  • 218.
    Krakhmalev, Pavel
    et al.
    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.
    Tribological behavior and wear mechanisms of MoSi2-base composites sliding against AA6063 alloy at elevated temperature2006In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 260, no 4-5, p. 450-457Article in journal (Refereed)
  • 219.
    Krakhmalev, Pavel
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Fredriksson, Gunnel
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Yadroitsava, Inna
    Yadroitsev, Igor
    In situ heat treatment in selective laser melted martensitic AISI420 stainless steels2015In: Materials & Design, ISSN 0264-1275, Vol. 87, p. 380-385Article in journal (Refereed)
  • 220.
    Krakhmalev, Pavel
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Influence of tool steel microstructure on origin of galling initiation and wear mechanisms under dry sliding against a carbon steel sheet, WOM 20072009Conference paper (Refereed)
  • 221.
    Krakhmalev, Pavel
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Rodil, Adeva
    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 microstructure on the abrasive edge wear of WC–Co hardmetals2007In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 263, no 1-6, p. 240-245Article in journal (Refereed)
  • 222.
    Krakhmalev, Pavel
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Ström, E.
    Li, C.
    Microstructure and properties stability of Al-alloyed MoSi2 matrix composites2004In: Intermetallics (Barking), ISSN 0966-9795, E-ISSN 1879-0216, Vol. 12, no 2, p. 225-233Article in journal (Refereed)
  • 223.
    Krakhmalev, Pavel
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Ström, E.
    Sundberg, M.
    Li, C.
    Microstructure, hardness and indentation toughness of C40 Mo(Si,Al)2/ZrO2 composites prepared by SPS of MA powders2003In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 48, no 6, p. 725-729Article in journal (Refereed)
  • 224.
    Krakhmalev, Pavel
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Ström, E.
    Sundberg, M.
    Li, C.
    Microstructure, hardness and indentation toughness of high-temperature C40 Mo(Si,Al)2/SiC composites prepared by SPS of MA powders2003In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 57, no 22-23, p. 3387-3391Article in journal (Refereed)
  • 225.
    Krakhmalev, Pavel
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Ström, E.
    Sundberg, M.
    Li, C.
    Processing, microstructure and properties of C40 Mo(Si,Al)2/Al2O3 composites, Materials Science and Engineering A, Volume 360, Issues 1-2, Pages 207-213, 20032003Article in journal (Refereed)
  • 226.
    Krakhmalev, Pavel
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Sukumaran, J.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Effect of microstructure on edge wear mechanisms in WC-Co2007In: International Journal of Refractory Metals and Hard Materials, ISSN 0958-0611, Vol. 25, no 2, p. 171-178Article in journal (Refereed)
    Abstract [en]

    Edge wear of nano to coarse WC–Co grades was investigated under two-body abrasion conditions using SiC abrasive at 2 and 15 N loads. With the fine abrasive utilized, a transition from homogeneous plowing in submicron grades to inhomogeneous grains pullout in coarse hardmetals was observed at the beginning stages. At final stages, plowing was detected in all the grades. When using the coarse abrasive, for all grades, flaking at the beginning and plowing at the final stages occurred. The performed numerical finite element simulation of the microstructural mechanical response showed good agreement to experimental results and was discussed in relation to the operative wear mechanisms observed. The found results demonstrated a remarkable influence of microstructure and abrasive size on the heterogeneous to homogeneous wear mechanisms transition at initial stages

  • 227.
    Krakhmalev, Pavel
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Sukumaran, J.
    Gåård, Anders
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    How hardmetals react to wear: Nano is not always the best2007In: Metal Powder Report, ISSN 0026-0657, E-ISSN 1873-4065, Vol. 62, no 2, p. 30-35Article in journal (Refereed)
  • 228.
    Krakhmalev, Pavel
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Yadroitsev, I.
    Univ Lyon, Ecole Natl Ingn St Etienne ENISE, DIPI Lab, F-42023 St Etienne, France..
    Microstructure and properties of intermetallic composite coatings fabricated by selective laser melting of Ti-SiC powder mixtures2014In: Intermetallics (Barking), ISSN 0966-9795, E-ISSN 1879-0216, Vol. 46, p. 147-155Article in journal (Refereed)
    Abstract [en]

    Transition metal silicides and carbides are attractive advanced materials possessing unique combinations of physical and mechanical properties. However, conventional synthesis of bulk intermetallics is a challenging task because of their high melting point. In the present research, titanium carbides and silicides composites were fabricated on the titanium substrate by a selective laser melting (SLM) of Ti -(20,30,40 wt.%)SiC powder mixtures by an Ytterbium fiber laser with 1.075 mu m wavelength, operating at 50 W power, with the laser scanning speed of 120 mm/s. Phase analysis of the fabricated coatings showed that the initial powders remelted and new multiphase structures containing TiCx, Ti5Si3C5, TiSi2 and SIC phases in situ formed. Investigation of the microstructure revealed two main types of inhomogeneities in the composites, (i) SiC particles at the interlayer interfaces and, (ii) chemical segregation of the elements in the central areas of the tracks. It was suggested and experimentally proven that an increase in laser power to 80 W was an efficient way to improve the laser penetration depth and the mass transport in the liquid phase, and therefore, to fabricate more homogeneous composite. The SLM Ti (20,30,40 wt.%)SiC composites demonstrated high hardness (11-17 GPa) and high abrasive wear resistance (3.99 x 10(-7)-9.51 x 10(-7) g/Nm) properties, promising for the applications involving abrasive wear. (C) 2013 Elsevier Ltd. All rights reserved.

  • 229.
    Krakhmalev, Pavel
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Yi, D.
    Nyborg, L.
    Preparation of nanocrystalline/amorphous structure in soft magnetic Fe-based alloys by mechanical alloying, 22nd Risoe International Symposium on Materials Science2001Conference paper (Refereed)
  • 230.
    Köhler, Andreas
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Agglomerations in Cellulose Fibre Reinforced Plastic Composite: A Micromechanical Model2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Degree project was performed by a Master’s student from Karlstad University and conducted at the Royal Institute of Technology during the spring of 2010. The project was performed as part of the Nordic project WoodFibre3D which is aimed to increase the technology intensity in the Swedish paper and forest products. Scientists from all over the Nordic region cooperate in the project. The aim of this study was to investigate how agglomerations of different cellulose pulp fibres reduce the ultimate tensile strength of cellulose fibre composite. In this particular sub project of the WoodFibre3D, the defects of injection moulded cellulose fibre composites were investigated. Defects such as fibre agglomerations are formed during manufacture. These agglomerations give rise to a heterogeneous stress fields, with stress concentrations at the agglomeration-matrix interfaces. Precursor and injection mould the raw material were produced to standardised test pieces. The test pieces were then scanned by x-ray microtomography followed by image analysis to segment matrix, fibres, agglomerations and voids in high resolution three dimensional digital images. After the scanning the test pieces were broken by tensile test before a second x-ray scan and fracture surface analysis. Agglomerations resemble triaxial arbitrarily oriented ellipsoids. For the ellipsoids the stress concentration is calculated iteratively in terms of maximum principal stress. Ellipsoids are also calculated in terms of stress intensity by assuming sharp crack like behaviour. Fracture analysis and micromechanical models showed a clear correlation between strength and the stress intensity of the large agglomerations in the composite. For stress concentration factor the micromechanical model was unable to identify any correlation. No vast systems of small agglomerations were found to cause failure.

  • 231.
    Larsen, Andreas
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Produktionsstrategi för Heavy Factory: En effektiv produktionsmix som genererar 20 000 produktionstimmar2016Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The aim of this work has been to develop proposals on how the utilization rate of the machines used for the processing of Yankee details can be increased. The work has been carried out at the Department of Production engineering at Valmet AB in Karlstad.

    The objective of the work was to identify one or more products, currently produced for external customers, which are suitable for a production launch for processing in the machine shop for manufacturing of Yankee cylinders. The objective has also been to present an efficient mix of production in the machine shop that with the selected product generates 20,000 production hours in the main machines.

    The work was carried out with a qualitative approach where interviews, observations and literature reviews were used to collect data. Secondary data were collected from different databases at Valmet. An early created project plan gave structure to the work and follow-up work took place with pulse meetings weekly at Valmet.

    An investigation was conducted of suitable products for a production launch for processing. After selecting the product various scenarios was analyzed to determine a mix of production that most efficient generate 20,000 production hours. The designed production mix appeared to generate some problems in terms of available resources, WIP, flow and available space in the machine shop. With the help of the Lean philosophy seven measures has been developed that will lead to an efficient mix of production is ​​achieved. The introduction of measures has been divided into three steps. Step one (1) is considered necessary to impose in order to achieve the production mix, while step two and three are important for flow efficiency and thereby to achieve an efficient mix of production.

    The results of the work show that the utilization rate of the most important machines in the machine shop can be raised through a production launch for processing of the product V164. Thus the product is manufactured for the wind power industry, a production launch for processing also mean less sensitivity to fluctuations in the market for tissue paper machines and thereby a more even workload can be generated.

  • 232.
    Larsson, Karl
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Nötning av verktygsstål vid plåtformning: Inverkan på arbetsmaterialets sträckgräns och påkletningsmotstånd för verktygsstål2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In today's industry, tools are more exposed to larger forces in sheet metal forming. As materials become stronger, larger forces are also needed to achieve a geometric change of the materials. Because of this, abrasion effects in the processes have increased and one of the most common one is galling. Galling is a form of wear where both adhesive and abrasive wear occur. This means that material comes off of the host material and sticks to the tool. When material has been transferred to the tool, it no longer has the original shape and can lead to irregularities in the material to be formed. So far companies have used lubricants to minimize it. As lubricants are increasingly regulated for environmental reasons, the industry must find other solutions to the problem. One solution is to create materials that are resistant to galling through their microstructure. There is still limited knowledge in this area and the aim of this study is to compare two tool steels and investigate which of them is most resistant to galling. The tool steel Caldie and Vancron Superclean will be tested against the materials DP600 and DP1000 usually used in sheet metal forming. Where the materials have different yield strengths, this is to see if it has an impact on sheet metal forming. To decide which tool steel is most suitable for sheet metal forming, a sliding test will be produced using the SOFS method. The sliding distance will describe how quickly galling occurs and thus the better material is determined. The abrasive traces of the materials were analyzed using an electron microscope to see how galling affected the tool steel and surface material.The result showed that the Vancron Superclean was more resistant to galling, as the tool steel slid over the DP600, while no conclusion could be drawn when slipping over DP1000.

  • 233. Larsson, Linda
    et al.
    Sjödahl, L.
    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.
    Microscopic 3-D Displacement Field Measurements using Digital Speckle Photography2004In: Optics and Lasers in Engineering, 41, 767-777 (2004)Article in journal (Refereed)
    Abstract [en]

    A technique to measure object shape and 3-D displacement fields in micro-scale is offered by microscopic stereo digital speckle photography. The displacement of the random features that are often present on many engineering surfaces when viewed in a microscope is measured with the system, using image correlation. In this paper the equipment, physical model and calibration routines are described. The technique can be applied for sub-mm sized objects of arbitrary shape for small deformation fields. As a verifying experiment, an in-plane rotation of a flat calibration plate is presented. The expected in-plane errors are shown to be less than 0.1 ?m and the corresponding out-of-plane errors about three times larger. As a pilot experiment, micro-structural paper expansion is studied, when exposed to humidity. The scaling properties of the microscope as well as the sampling criteria and reliability of the system are discussed in detail

  • 234.
    Larsson, Marcus
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Transportör: Lokal logistik2012Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This report is the result of a project work carried out at Karlstad University in conjunctionwith the local consulting firm Camatec where most of the work has been performed.The work can be classified as a classic engineering work with supportive theories andcalculations which in this context is relevant.The engineering project has focused on developing new standards for a conveyor that is usedin the Värmland paper industry where large rolls of paper are produced. A conveyor can takeits appearance in many different forms but in this thesis it has been an exemplary look and ithas also become modulatable with a central section, a drive end and a turning end.The construction work has been build under CAD programs such as Pro Engineer, drawingshave been created and costings have been analyzed. Strength calculations have been made andcooperation from several different companies have erected to explore different solutions andideas for a modern and sustainable conveyor.

  • 235.
    Lindholm, Marcus
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Column bolt calculation: Column bolt calculation on a 1200T HAP Raufoss aluminium extrusion machine2005Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This degree project is a verification of a hand made calculation made by Semcon CAE inGothenburg, Sweden. The main purpose has been to investigate how loads in a pre-tensionedbolt appear and how material displacement and contact pressures in the nuts affect bolt joints.A FEM-model has been created to imitate the reality as much as possible this to verifySemcon’s calculations. The result of the FEM-model has been compared with the result fromSemcon report 87-082-008, see appendix 2. Thus the Semcon original report has beenverified.The results between the Semcon report 87-082-008and the FEM calculations can be seen inchapter 2 and appendix 1.The basic data of the degree exam is the Semcon report and is the starting point of the wholeproject. All data regarding dimensions, geometry, materials and so on is based on the datafrom the Semcon report.A fatigue analysis based on the FEM-results was not conducted. This was due to thesimilarities in result between the previous Semcon report and this study

  • 236.
    Lindqvist, Tobias
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Analys och utformning av fordonschassi2016Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The thesis was preformed for Precer in Karlstad and it´s a part of the program for graduate engineers in mechanical engineering at the University of Karlstad. The employer Precer Autotech offers technical solutions for the production of electricity through clean combustion of various types of solid fuels. The technology is adaptable for use as a recharge source in different types of hybrid vehicles as well as for production of electricity for homes and cottages. Precer Autotech, in collaboration with the European Space Agency (ESA), has developed new types of fuels and powertrains and is currently in the process of bringing these into an environmental friendly concept vehicle. The dissertations purpose is to develop a frame for a concept vehicle, which is driven by this new type of driveline. The results from the study show a model of a frame for this concept vehicle and evaluations around the torsion stiffness of the frame. Material proposal will also be discussed in the report.

  • 237. Lindskog, P
    et al.
    Barbier, Christophe
    Karlstad University, Faculty of Technology and Science, Materials Science. 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, Department of Mechanical and Materials Engineering.
    Jelagin, D
    Larsson, P.L.
    Optimization as a tool for characterization of advanced constitutive models describing powder compaction2007Conference paper (Refereed)
    Abstract [en]

    The applicability of optimization procedures used in combination with advanced constitutive models, describing dry pressing powder compaction, is investigated by aid of standard finite ele- ment and optimization commercial packages. It is found that, at fairly general conditions, this can be expected to be a very advantageous approach at material characterization

  • 238.
    Lindvall, Fredrik W.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Measurement and mechanisms of galling in sheet metal forming: A literature reviewManuscript (preprint) (Other academic)
  • 239.
    Lindvall, Fredrik W.
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Tool steel and contact geometry influence on galling initiation in lubricated sliding on carbon steel sheets2009In: Proceedings of the 8th International Tooling Conference, Vol 1, 2009, p. 189-198Conference paper (Refereed)
    Abstract [en]

    In sheet metal forming operations, sliding contact may cause adhesive wear of sheet materials with transfer of worn material to the tool surface, a wear damage process named galling. It results in loss of product quality, process performance and tool lifetime. The industrial experience of the optimal combination of sheet metal grades, tool steel grades, tool geometry and lubrication to increase the tool performance is not clearly understood. Accordingly, simulation of wear of sheet metal forming operation in laboratory conditions in order to quantify tendency of a tool material to galling is not a trivial problem neither. In the present study two tool steel grades, an ESR made 8%Cr cold work tool steel and a superior PM made high speed steel, were tested with different test tool geometries to obtain different contact pressure conditions. A slider on flat sheet (SOFS) test equipment was utilized, where a disc made of tool steel was slid along lubricated carbon steel sheets of different strengths. The sliding tool discs were prepared so that one elliptical and two linear contacts were simulated, in order to study their influence on distance to galling initiation. Normal and friction force data were collected, galling initiation was detected by analysis of the friction curve and verified by SEM and OP analysis of the tool surfaces and sheet sliding tracks. It was found that under selected test conditions, galling initiation was remarkably dependent on tool material as well as geometry.

  • 240.
    Lindvall, Fredrik W.
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Bay, Niels
    Department of Mechanical Engineering, Technical University of Denmark.
    The effect of grinding and polishing procedure of tool steels in sheet metal forming2010In: ICTPM 2010, 2010, p. 603-612Conference paper (Refereed)
    Abstract [en]

    The surface finish of tools in sheet metal forming has a large influence on the performance of the forming tool. Galling, concern of wear in sheet metal forming, is a severe form of adhesive wear where sheet material is transferred on to the tool surface. By polishing the tools to a fine surface finish, material pick-up has traditionally been reduced, but some surface preparations withstand adhesive wear better. To investigate the effect on galling performance of different surface preparations lubricated tests have been performed using a strip reduction rig. Two different tool materials, Vancron 40 and Vanadis 6 and up to ten different grinding and polishing treatments were tested against AISI 316 stainless steel. The tests showed that an optimum surface preparation might be found at the transition between abrasive and adhesive wear.

  • 241. Ljungqvist, Carl-Henrik
    et al.
    Lyng, Reidar
    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.
    Evaluation of PFI beating on the strain to failure of spruce fibres using single fibre fragmentation2005Other (Other (popular science, discussion, etc.))
  • 242. Ljungqvist, Carl-Henrik
    et al.
    Lyng, Reidar
    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 fibre damage in latewood spruce tracheids on strain to failure of wood fibres determined be Weiull modeling2004In: Nordic Pulp and Paper Research Journal, 19 2004 pp 164-169Article in journal (Refereed)
  • 243. Ljungqvist, Carl-Henrik
    et al.
    Lyng, Reidar
    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 observable damage on mature latewood spruce fiber properties2003Conference paper (Refereed)
  • 244. Ljungqvist, Carl-Henrik
    et al.
    Lyng, Reidar
    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.
    Measuring the strain to failure for wood fibres - influence of fibre wall damage2003Other (Other (popular science, discussion, etc.))
  • 245.
    Lundberg, Ludvig
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Modular front lamp to a combat vehicle: With focus on modern design and manufacturability2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of the project is to, with the help of relevant course literature, knowledge obtained from previous courses and with the help of supervisor and colleagues, produce a concept suggestion of how the front lamp to a combat vehicle could be designed. The purpose is also, with the help of meticulous documentation and structured work, to do a project that it will possible to continue working on and eventually construct a prototype from.

    The methods that were used during this project were for example WBS, scrum board, Gantt-schedule and elimination matrix.

    The project started with a planning phase where the project plan and time schedules were set up. Then was the pilot study which is used to gather the knowledge needed to carry out the project. The information gathered in the pilot study were then summarized in a criterion matrix in the product specification. These criterions were then used in the concept selection phase as guidelines when generation ideas and develop concepts.

    After the concept selection three concept were chosen and presented for the employer and, in conjunction with the employer, it was decided to combine these concepts into one. 3D-models were then done with the help of CAD (Computer Aided Design) to illustrate this combined concept and associated material selection and manufacturing methods were done.

    The conclusion of this project was that the amount of innovative ideas and solutions were limited since the product is regulated by military standards and criterions from customers. Therefore, the outcome of the project is similar to previous versions, which is unfortunate, since the goal with the project were to come up with new and innovative concepts of how to design the front lamp. But even though this concepts design looks like the old design, it has few completely new things to it that haven’t existed in previous versions.

    It was also realized how much time you save during the project if you do a detailed planning at the start of the project and how valuable it is to be structured in the work process.

    Further work that is needed to be done on the project before the production of a prototype are calculations of the cost to manufacture and produce the product, strength calculations of the stress concentrations etc., and drawings of the product. The components of the front lamp, i.e. horn, lamps, sensors etc., also need to be selected in accordance with the criterion matrix.

  • 246.
    Masoumi Tochahi, Seyed Amirhosein
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Self-locking in electrical actuators2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays all different kind of actuators is used in a widespread range. Their job is to transmit force, bear load, produce linear force, adjust height etc. Hydraulic fluid pressure, pneumatic pressure and electrical current usually change in to some sort of motion in actuators. This report is related to electrical actuators and self-locking problem, which is really common in them. The thesis report has been performed at Reac AB in Åmål, Sweden, a major supplier of wheel chair actuators.

     

    Electrical actuators have vast usage and they are versatile but in some cases they face with different working situation like dynamic forces. Recent generation of electrical actuators which used in wheelchairs (imagine moving wheelchair in bumpy road) have self-locking problem, which it means that they will lose their position after while under compression load. This fact will lead to de-calibration of the control system. Approximately 90% of  AB production is related to the electrical wheelchairs. Challenging point here is dynamic force which can lead to de-calibration of potentiometer and failure of device.

     

    Load capacity of certain actuator (RE25) is 2000 N. In this project different method has been used to simulate and calculate different aspects. Design of new part, material selection and improvement of some parts are most important. During the period lots of static and dynamic tests, CAD design and FEM analysis have been executed.

     

    Shock absorber, lock pin and new material have been run parallel and more or less all those three had a positive effect.

     

    Finally with design and selection of lock pin solution included cogwheel and pin, we overcome to the problem with great results. 

  • 247.
    Medvedeva, Anna
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Performance of advanced tool steels for cutting tool bodies2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Performance of indexable insert cutting tools is not only about the performance of cutting inserts. It is also about the cutting tool body, which has to provide a secure and accurate insert positioning as well as its quick and easy handling under severe working conditions. The common damage mechanisms of cutting tool bodies are fatigue and plastic deformation. Cutting tools undergo high dynamic stresses going in and out cutting engagement; as a result, an adequate level of fatigue strength is the essential steel property. Working temperatures of tool bodies in the insert pocket can reach up to 600°C, why the tool steel requires high softening resistance to avoid plastic deformation. Machinability is also essential, as machining of the steel represents a large fraction of the production cost of a cutting tool.

    The overall aim of the study is to improve the tool body performance by use of an advanced steel grade with an optimized combination of all the demanding properties. Due to the high-temperature conditions, the thesis concerns mostly hot-work tool steels increasing also the general knowledge of their microstructure, mechanical properties and machinability.

    Knowing the positive effect of sulphur on machinability of steels, the first step was to indentify a certain limit of the sulphur addition, which would not reduce the fatigue strength of the tool body below an acceptable level. In tool bodies, where the demand on surface roughness was low and a geometrical stress concentrator was present, the addition of sulphur could be up to 0.09 wt%.

    Fatigue performance of the cutting tools to a large extent depended on the steel resistance to stress relaxation under high dynamic loading and elevated temperatures. The stress relaxation behaviour, material substructure and dislocation characteristics in low-alloyed and hot-work tool steels were studied using X-ray diffraction under thermal and mechanical loading.  Different tool steels exhibited different stress relaxation resistance depending on their microstructure, temper resistance and working temperature. Hot-work tool steels showed to be more preferable to low-alloyed tool steels because of their ability to inhibit the rearrangement and annihilation of induced dislocations.

    High-temperature softening resistance of the hot-work tool steels was investigated during high-temperature hold-times and isothermal fatigue and discussed with respect to their microstructure. Carbide morphology and precipitation were determined using scanning and transmission electron microscopy.

    Machinability of a prehardened hot-work tool steel of varying nickel content from 1 to 5 wt% was investigated in end milling and drilling operations. Machining the higher nickel containing steels resulted in longer tool life and generated lower cutting forces and tool/workpiece interface temperature. The difference in machinability of the steels was discussed in terms of their microstructure and mechanical properties. 

  • 248.
    Medvedeva, Anna
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Properties of tool steel for tool holder application: A litterature review2008Report (Other academic)
    Abstract [en]

    Large improvements in cutting tool design and technology have been achieved in the last decades. But the problem of improving the tool body material is not adequately studied. In the present study, the different aspects associated with the steel properties as related to the milling cutter body application are reviewed. The working performance of a tool holder depends in particular on the fatigue strength, high temperature properties and machinability of the tool steel used.

    Rotating tools, tool going in and out of cutting engagement, impose dynamic stresses and require adequate fatigue strength off the tool. Different publications, as well as internal investigation at Uddeholm Tooling AB show that the working temperatures of milling cutter bodies in the insert pocket vary from 300 to 600 degrees Celsius depending on the cutting conditions and material of the workpiece. As a result, steel for this application needs good hot properties such as high temper resistance, high hot hardness values, etc. Machinability is also essential as machining of steel represents a large fraction of the production cost of a milling cutter. Its complex shape with flutes and insert pockets as well as small thread holes and small deep holes for cooling channels require time consuming and advanced machining operations.

    The essential properties mentioned above were characterized with the emphasis to the steel type, its microstructure and purity, processing and surface treatment and strong interrelations between them.

  • 249.
    Medvedeva, Anna
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Tool steel for tool holder applications: microstructure and mechanical properties2008Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Large improvements in cutting tool design and technology, including the application of advanced surface engineering treatments on the cemented carbide insert, have been achieved in the last decades to enhance tool performance. However, the problem of improving the tool body material is not adequately studied.

    Fatigue is the most common failure mechanism in cutting tool bodies. Rotating tools, tool going in and out of cutting engagement, impose dynamic stresses and require adequate fatigue strength of the tool. Working temperatures of milling cutter bodies in the insert pocket can reach up to 600°C depending on the cutting conditions and material of the workpiece. As a result, steel for this application shall have good hot properties such as high temper resistance and high hot hardness values to avoid plastic deformation in the insert pocket of the cutting tool. Machinability of the steel is also essential, as machining of steel represents a large fraction of the production cost of a milling cutter.

    This thesis focus on the improvement of the cutting tool performance by the use of steel grades for tool bodies with optimized combination of fatigue strength, machinability and properties at elevated temperatures.

    The first step was to indentify the certain limit of the sulphur addition for improved machinability which is allowable without reducing the fatigue strength of the milling cutter body below an acceptable level. The combined effect of inclusions, surface condition and geometrical stress concentrator on the fatigue life of the tool steel in smooth specimens and in tool components were studied in bending fatigue.

    As the fatigue performance of the tools to a large extent depends on the stress relaxation resistance at elevated temperature use, the second step in this research was to investigate the stress relaxation of the commonly used milling cutter body materials and a newly steel developed within the project. Compressive residual stresses were induced by shot peening and their response to mechanical and thermal loading as well as the material substructures and their dislocation characteristics were studied using X-ray diffraction.

    Softening resistance of two hot work tool steels and a newly developed steel was investigated during high temperature hold times and isothermal fatigue and discussed of with respect to their microstructure. Carbide morphology and precipitation as well as dislocation structure were determined using transmission electron microscopy and X-ray line broadening analysis.

  • 250.
    Medvedeva, Anna
    et al.
    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.
    Gunnarsson, Staffan
    Research and Development, Uddeholm Tooling AB.
    Inclusions, Stress Concentrations and Surface Condition in Bending Fatigue of an H13 Tool Steel2008In: Steel research, ISSN 0177-4832, ISSN 1869-344X, Vol. 79, no 5, p. 376-381Article in journal (Refereed)
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