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  • 101.
    Ekengren, Jens
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Bergström, Jens
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Detecting large inclusions in steels: evaluating methods2009Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 80, nr 11, s. 854-858Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The distributions of large non-metallic inclusions in two steel grades have been investigated using light optical microscopy, scanning electron microscopy and ultrasonic fatigue testing in the gigacycle range. The different methods have inherently different capabilities for finding inclusions in different size ranges. A measure of the distribution of large inclusions is proposed as the size S at which half of the fatigue specimens are expected to contain at least one inclusion of size S or larger, corresponding to 50% failure probability. Values of S are obtained using the volume distribution estimated by the three methods. Extrapolation from microscopy measurements on surfaces agree with fatigue fractography results regarding density of large inclusions, as measured by the proposed ranking variable S

  • 102.
    Ekengren, Jens
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Bergström, Jens
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Estimating the volume distribution of large defects using Generalized Extreme Values2011Inngår i: Extremes, ISSN 1386-1999, E-ISSN 1572-915XArtikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The presence of defects, such as oxides and other non-metallic inclusions, is an important factor in determining the properties of steels. Due to improvements in the manufacturing of high-quality steels, the amount of large defects has decreased and therefore it has become increasingly difficult to accurately determine their distribution using conventional methods. Previously, a method for estimating the distribution of large defects using a conversion from the Gumbel distribution has been presented. However, it has been shown that the Gumbel distribution is not always appropriate for modelling the sizes of the largest defects and that the Generalized Extreme Values (GEV) distribution should be used instead. In this work a more general method for the estimation of the total volume distribution of large defects isproposed, showing how the volume distribution may be calculated from the estimated parameters for the GEV distribution. The new method is applied to the results of a series of specimens made from high-quality tool steel tested in ultrasonic resonance fatigue. Possible methods for obtaining the confidence limits of thevolume distribution are also discussed.

  • 103.
    Ekengren, Jens
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Bergström, Jens
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Extreme value distributions of inclusions in six  steels2012Inngår i: Extremes, ISSN 1386-1999, E-ISSN 1572-915X, Vol. 15, s. 257-265Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a prevailing assumption that the largest inclusions in steel volumes follows mode I of the Generalized Extreme Values (GEV) distribution. In this work, the GEV distributions of non-metallic inclusions in six different high performance steels, of different grades and processing routes, were investigated by means of fractography of inclusions causing failure in ultrasonic fatigue testing to one billion cycles and all three modes of the GEV were found for the different steel grades. Values of the shape parameter ξ of the GEV distribution as high as 0.51 (standard deviation 0.11) were found in one steel grade. Thus, the present results show that the assumption of GEV-I (Gumbel, LEVD) distribution has to be substantiated before being used to estimate the size of the largest inclusions.

  • 104.
    Ekengren, Jens
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Bergström, Jens
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Extreme value distributions of inclusions in six steels2008Annet (Annet (populærvitenskap, debatt, mm))
  • 105.
    Ekengren, Jens
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Bergström, Jens
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Influence of life length on estimated defect  distribution in a low defect steel material2011Inngår i: Proceedings of the Fifth International Conference on Very High Cycle Fatigue / [ed] C. Berger and H.-J. Christ, 2011, s. 177-182Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper reports on results of very high cycle fatigue tests on a steel with a relatively low number of defects per unit volume. Two series of newly designed dog-bone specimens, with low stress gradients, were tested at two constant stress levels, aiming at providing fatigue life lengths of 106–108 cycles and 107–109 cycles, respectively. Fatigue-initiating defects on the fracture surfaces were measured and the corresponding size distributions were analysed to investigate the influence of the elevated stress level needed to achieve shorter life lengths.The presented results indicate a difference between the distribution of initiating defects in the long and shorter life length test series. The main conclusion is that fixed stress level fatigue testing to life lengths around 107 cycles may be a suitable method to estimate the content of large defects in low defect steel materials, provided a suitable test specimen geometry with low stress gradients is used.

  • 106.
    Ekengren, Jens
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Kazymyrovych, Vitaliy
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Bergström, Jens
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Assessment of strength and inclusions of Tool Steels in Very High Cycle Fatigue2009Inngår i: Proceedings of the 8th International Tooling Conference, Vol 1 / [ed] P. Beiss, C. Broeckmann, S. Franke, B. Keysselitz, Verlag Mainz, Wissenschaftsverlag , 2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Fatigue strength is an important material property for many tooling applications, particularly in high performance applications. The research in Very High Cycle Fatigue (VHCF) has demonstrated that the traditional fatigue limit may not be valid for many materials subjected to 107 or more load cycles. Presently, both materials data and mechanism knowledge is missing on VHCF applications, even though many components are run at these life lengths. The fatigue strength is commonly controlled by different defects initiating failure, as in well controlled laboratory experiments may be internal inclusions. In this paper VHCF experimental testing was accomplished by the use of ultrasonic fatigue testing run at 20 kHz allowing long life evaluation within reasonably short test time. Fatigue strength, failure mechanisms and inclusion content were accordingly assessed. Fatigue strength data on H13 tool steel are presented, as well as a statistical approach considering available defect distribution and load distribution in the critically stressed volume, important to both steel supplier and end-user.

  • 107.
    Ekengren, Jens
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Kazymyrovych, Vitaliy
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Burman, Christer
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Bergström, Jens
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Relating gigacycle fatigue to other methods in evaluating the inclusion distribution of a H13 tool steel2007Inngår i: Fourth International Conference on Very High Cycle Fatigue (VHCF-4) / [ed] John E. Allison, J. Wayne Jones, James M. Larsen & Robert O. Ritchie, TMS (The Minerals, Metals & Materials Society) , 2007, s. 45-50Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Inclusions play a crucial role for the fatigue properties of high strength steel, but to find the largest inclusions by microscopy measurements large areas have to be examined.In this study ultrasonic gigacycle staircase fatigue testing has been used to find large inclusions in an H13 tool steel. The inclusions have been examined in SEM and their size distribution modeled using methods from extreme value statistics. The inclusion distribution obtained from the fatigue crack surfaces is compared to distributions acquired by microscopy study of cross sections as well as ultrasound immersion tank measurements and to the corresponding staircase fatigue data via the Murakami √Area model.It is shown that the fatigue method more effectively finds large inclusions than the other methods. It is also shown that the correlation between predictions of inclusion sizes by the √Area model from stress levels and fatigue initiating inclusions is weak forthis material.

  • 108.
    Ekengren, Jens
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Kazymyrovych, Vitaliy
    Burman, Christer
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Bergström, Jens
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    RELATING GIGACYCLE FATIGUE TO OTHER METHODS IN EVALUATING THE INCLUSION DISTRIBUTION OF A H13 TOOL STEEL2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Inclusions play a crucial role for the fatigue properties of high strength steel, but to find the

    largest inclusions by microscopy measurements large areas have to be examined. In this study ultrasonic gigacycle staircase fatigue testing has been used to find large inclusions in an H13 tool steel. The inclusions have been examined in SEM and their size

    distribution modeled using methods from extreme value statistics. The inclusion distribution obtained from the fatigue crack surfaces is compared to distributions acquired by microscopy study of cross sections as well as ultrasound immersion tank measurements and to the corresponding staircase fatigue data via the Murakami \sqrt{Area} model. It is shown that the fatigue method more effectively finds large inclusions than the other methods. It is also shown that the correlation between predictions of inclusion sizes by the \sqrt{Area} model from stress levels and fatigue initiating inclusions is weak for this material

  • 109.
    Ekhagen, Sebastian
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Stability of electron acceptor materials for organic solar cells: a work function study of C60/C70 derivatives and N22002019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Thin films of the fullerenes PC60BM and PC70BM and the non-fullerene N2200, three popular electron acceptor materials in organic photovoltaics, have been studied, using both the Kelvin probe method as well as ultraviolet photoelectron spectroscopy. With these methods the work function was measured, as well as the highest occupied molecular orbital (HOMO) onset. Additionally band bending effects were studied by illuminating the samples while measuring the work function with the Kelvin probe so called surface photovoltage. Sample of each material was exposed to either air and simulated sunlight or N2 and simulated sunlight, for different length of time, to observe how the materials work function evolves after exposure to the different conditions. It was observed that, as expected from previous studies, that PC60BM was less photo-stable than PC70BM. Additionally, the work function of PC60BM changed significantly by storage in N2. Each material after exposure for 24h to air and light, was annealed and measured with the Kelvin probe. A restoring effect was observed,  for the non-fullerene material N2200. All three materials developed an increasing surface photovoltage, which suggest increased band bending, when exposed to air and light, indicating that due phot-oxidization, charges are redistributed at the surface of the film. The fullerenes showed a larger surface photovoltage effect than the non-fullerene materials. A difference between the work function values obtained from the Kelvin probe method and the ultraviolet photoelectron spectroscopy could be seen, however the exact reason for this couldn't be isolated within this thesis, but was discussed.

  • 110.
    Elschich, Ahmed
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Thermo-mechanical Fatigue of Electrical Insulation System in Electrical machine2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Electrical machines in electrified heavy-duty vehicles are subjected to dynamic temperature loadings during normal operation due to the different driving conditions. The Electrical Insulation System (EIS) in a stator winding is aged as an effect of these dynamic thermal loads. The thermal loads are usually high constant temperatures and thermal cycling. The high average constant thermal load is well-known in the electrical machine industry but little is known about the effect of temperature cycling. In this project, the ageing of the EIS in stator windings due to temperature cycling is examined.

    In this project, computational simulations of different simplified models that represent the electrical insulation system are made to analyse the thermo-mechanical stresses that is induced due to thermal cycling. Furthermore, a test object was designed and simulated to replicate the stress levels obtained from the simulations. The test object is to ease the physical testing of electrical insulation system. Testing a complete stator takes time and has the disadvantage of having a high mass, therefore a test object is designed and a test method is provided. The results from the finite element analysis indicate that the mechanical stresses induced will affect the lifetime of the electrical insulation system.

    A sensitivity study of several thermal cycling parameters was performed, the stator core length, the cycle rate and the temperature cycle amplitude. The results obtained indicate that the stator core length is too short to have a significant effect on the thermo-mechanical stresses induced. The results of the sensitivity study of the temperature cycle rate and the temperature cycle amplitude showed that these parameters increase the thermo-mechanical stresses induced.

    The results from the simulations of the test object is similar to the results from the simulations of the stator windings, which means that the tests object is valid for testing. The test method that is most appropriate is the power cycling test method, because it replicates the actual application of stator windings. The thermally induced stresses exposing the slot insulation exceeds the yield strength of the material, therefore plastic deformation may occur only after one thermal cycle. The other components in the stator are exposed to stresses below the yield strength.

    The thermally induced stresses exposing the slot insulation are high enough to low cycle fatigue the electrical insulation system, thus thermo-mechanical fatigue is an ageing factor of the electrical insulation system.

  • 111.
    Emanuelsson, Christian
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Scanning Electron Microscopy study of Macbat regeneration effect on lead-acid battery electrodes2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Electrodes from lead-acid batteries were studied using scanning electron microscopy and energy dispersive spectroscopy. This to observe the effects of cycling on the batteries and how a capacity recovery process, known as Macbat regeneration, affected the active material with focus on hard sulphation. First, two new batteries were cycled for two months and electrodes from them were studied when the batteries were new, cycled, fully charged after cycling and regenerated after cycling. Then electrodes from a separate battery that had been used in industry was studied prior to and after Macbat regeneration. On the cycled batteries it was found that after the cycling of the batteries no hard sulphation were present on the electrodes. The study of the separate battery showed that the battery had hard sulphation in its electrodes and that the Macbat regeneration was able to remove hard sulphation both on the surface of the electrodes and also inside the active material.

  • 112. Epure, Alexandru
    Maskinduglighet på planlaserskärare2008Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Lars Höglund AB is one of Scandinavia’s most qualified manufacturers of sheet metal products and provides custom designed products of very detailed precision. One of the main methods of manufacturing is laser cutting. When Lars Höglund AB signed up a new customer, with high demands in tolerances for the products, Lars Höglund AB thought it would be necessary to know the capability of the laser cutting machine. Also the process of how to retrieve this capability was interesting.

     

    The capability will be researched for the following elements:

     

    • Cutting right angles in squares with a corner radius of 1 mm
    • Cutting corners which are not right angle
    • Cutting of circles with constant radius

     

    Measurements were made on 150 pieces of sheet metal details, which had been cut out by the machine.  The data from the measurements where later used to study the capability. The capability study includes such things as calculations of capability indexes Cp and Cpk, the calculations are based on histograms and lean-mean-curves, constructed from the measurement data. The capability of the laser cutting machine was high except for some elements. Those elements with minor capability were the cutting of corner two and three for the rectangles which had a smaller radius than expected, side X for the triangles which were too long and also the diameter of the circles were too big. Advices on how to correct the faults have been given if Lars Höglund AB wants to further more improve the capability of the machine.

  • 113.
    Erhardsson, Erik
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Aktivering av en dissolvingmassa med enzymer före en konventionell viskosprocess2009Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    In conventional viscose manufacturing, a large amount of carbondisulfide is consumed. This amount has to be decreased to keep the production cost down and to reduce the environmental impact. The purpose with this work was to show if an enzyme treatment of a dissolving pulp could increase the degree of substitution in the viscose so that the amount of carbon disulfide consumed in the process could be decreased. Previous investigations by Kvarnlöf (2007), Engström et.al. (2006) and Henriksson et.al. (2005) has shown that the reactivity of a dissolving pulp (the cellulose raw material) increased when it was pre-treated with endoglucanase (enzyme). Kvarnlöf (2007) also showed that the amount of carbon disulfide that is needed to produce an ordinary viscose (in this work a more viscous viscose has been investigated) could be reduced with one third because of the enzyme treatment.

     

    In this thesis, viscose has been manufactured in a laboratory where the process has been adapted to look like the industrial as far as possible. Analyses were done on the viscose viscosity and degree of substitution. A reference curve was made with the percentage carbon disulfide load versus the viscose gamma number (degree of substitution). Then it was investigated how an enzyme treatment of the dissolving pulp affected the viscose. After the enzyme treatment, the manufacturing process for viscose was done in the exact same way as when the reference tests were done. The enzyme used in this thesis was Carezyme which contents endoglucanase. Then the results from the analyses of the viscose manufactured from enzyme treated dissolving pulp and the reference curve was compared. A positive result would have been that viscose manufactured with enzyme treatment gets a higher gamma number than viscose, with the same load of carbon disulfide, manufactured in the regular way.

     

    The results showed that the degree of substitution had no effect at all; the viscose that has been manufactured from enzyme treated dissolving pulp resulted in gamma numbers on or very close to the reference curve. The only effect that could be shown was a decrease in viscosity, which unfortunately was an unwanted effect. The enzyme treatment has also hampered the process, where shorter fibres among other things have given poorer dewatering properties. Analyses on the viscose manufactured in the laboratory showed that it didn't have the same characteristics as viscose manufactured in a plant.

  • 114.
    Eriksson, Mats
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Sliding wear performance of electroplated hard chromium and autocatalytic nickel-phosphorus coatings at elevated temperatures2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis was written for a Swedish valve manufacturer to find out in what temperature regimes it was possible to replace electroplated hard chromium with autocatalytic electroless nickel-phosphorus. In this work the dry sliding wear properties of electroplated hard chromium and autocatalytic electroless nickel-phosphorus(10% P) were compared. All tests and investigations were done by using available equipment at Karlstads University. The tests were made to find out how the wear of these coatings behaved at different temperatures, how different substrates influence the wear of these coatings and how the roughness of the substrate surface influence the wear properties of these coatings.

    The method used for the wear tests was block-on-ring with a counterformal contact mode. The tests were executed in room temperature, 300C and 400C; with a normal load of 100N, sliding speed was 150rpm and duration of the tests were 15 minutes. All tests were done in an argon gas atmosphere. The coatings was deposited onto the cylinders with a thickness of 30µm. The different substrates used were an austenitic stainless steel(1.4404) and an austenitic-ferritic(duplex) stainless steel(1.4460). Half of the austenitic cylinders had a machined surface and all the others(including duplex cylinders) were machined and grinded to achieve a smoother surface. The blocks used as countersurface were made out of austenitic-ferritic(duplex) stainless steel(1.4460).

    Equipment used to investigate the wear tracks were stereo microscopy, profilometer, microhardness tester and scanning electron microscopy(SEM). The coatings were investigated in matter such as wear depth, wear mode, wear mechanism, chemical composition, topography, morphology, cross-section and hardness.

    The results of this work showed that the nickel coating wear tracks maximal depth were less deep than those of hard chrome, at room temperature. At elevated temperatures the performance varies. The coatings deposited onto cylinders made out of duplex stainless steel performed better than those deposited onto austenitic cylinders. The nickel coating performed better deposited onto the substrates with smooth surface and the chrome coating performed better deposited onto the substrates with rough surface

  • 115.
    Erothu, Harikrishna
    et al.
    Aston University, England.
    Kolomanska, Joanna
    Aston University, England.
    Johnston, Priscilla
    Aston University, England.
    Schumann, Stefan
    Heraeus Deutschland GmbH & Co KG, Germany.
    Deribew, Dargie
    Belect OPV GmbH, Germany.
    Toolan, Daniel T. W.
    University Sheffield, England.
    Gregori, Alberto
    University Pau & Pays Adour, France..
    Dagron-Lartigau, Christine
    University Pau & Pays Adour, France..
    Portale, Giuseppe
    ESRF European Synchrotron, France.
    Bras, Wim
    ESRF European Synchrotron, Netherlands Org Sci Res, DUBBLE ESRF Beamline BM26, F-38043 Grenoble 9, France..
    Arnold, Thomas
    Diamond Light Source Ltd, England.
    Distler, Andreas
    Belect OPV GmbH, Germany.
    Hiorns, Roger C.
    CNRS, France.
    Mokarian-Tabari, Parvaneh
    National University Ireland University Coll Cork, Ireland.
    Collins, Timothy W.
    National University Ireland University Coll Cork, Ireland.
    Howse, Jonathan R.
    University Sheffield, England.
    Topham, Paul D.
    Aston University, England.
    Synthesis, Thermal Processing, and Thin Film Morphology of Poly(3-hexylthiophene)-Poly(styrenesulfonate) Block Copolymers2015Inngår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 48, nr 7, s. 2107-2117Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of novel block copolymers, processable from single organic solvents and subsequently rendered amphiphilic by thermolysis, have been synthesized using Grignard metathesis (GRIM) and reversible addition-fragmentation chain transfer (RAFT) polymerizations and azide-alkyne click chemistry. This chemistry is simple and allows the fabrication of well-defined block copolymers with controllable block lengths. The block copolymers, designed for use as interfacial adhesive layers in organic photovoltaics to enhance contact between the photoactive and hole transport layers, comprise printable poly(3-hexylthiophene)-block-poly(neopentyl p-styrenesulfonate), P3HT-b-PNSS. Subsequently, they are converted to P3HT-b-poly(p-styrenesulfonate), P3HT-b-PSS, following deposition and thermal treatment at 150 degrees C. Grazing incidence small- and wide-angle X-ray scattering (GISAXS/GIWAXS) revealed that thin films of the amphiphilic block copolymers comprise lamellar nanodomains of P3HT crystallites that can be pushed further apart by increasing the PSS block lengths. The approach of using a thermally modifiable block allows deposition of this copolymer from a single organic solvent and subsequent conversion to an amphiphilic layer by nonchemical means, particularly attractive to large scale roll-to-roll industrial printing processes.

  • 116.
    Falk, Erik
    et al.
    Karlstads universitet, Institutionen för ingenjörsvetenskap, fysik och matematik.
    Magnusson, Martin
    Karlstads universitet, Institutionen för ingenjörsvetenskap, fysik och matematik.
    Svetspåverkan på nickelaluminiumbrons2007Independent thesis Basic level (professional degree), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    Detta examensarbete har utförts åt Rolls-Royce AB Kristinehamn som tillhör den marina divisionen av koncernen. De tillverkar fasta/ställbara fartygspropellrar, pod- och vattenjetsystem. Detta arbete är en materialundersökning angående bronspropellrar. Propellerbladen sandgjuts och under gjutprocessen uppstår porositeter som inte är önskvärda då de försämrar materialets hållfasthet. Dessa svetsas igen med hjälp av TIG-svetsning.

    Rolls-Royce vill få ökad förståelse hur dessa svetsreparationer påverkar materialets egenskaper med avseende på mikrostruktur, hårdhet och draghållfasthet.

    Det finns klassningssällskap som har bestämmelser angående fartygskonstruktion och de har då även regler angående reparationssvetsning av bronspropellrar samt om olika värmebehandlingar efter svetsningen. Rolls-Royce vill ha en sammanställning av vad klassningssällskapen säger om värmebehandling efter reparationssvetsning på bronspropellrar.

    Totalt tio dragprov utfördes, två som referens, åtta svetsade varav två ej värmebehandlade, två avspänningsglödgade 315°C, två värmebehandlade 500°C enligt Rolls-Royce WPS (Welding Procedure Specification) samt två anlöpta 650°C. Svetsbrott vid dragprovningen uppkom i samtliga prov som var ovärmebehandlade och avspänningsglödgade, men för proven som var värmebehandlade vid 500°C inträffade ett av brottet i grundmaterialet och för 650°C skedde samtliga brott i grundmaterialet. Detta tyder på att anlöpningen stärkt svetsens egenskaper, gentemot grundmaterialet. Därefter utfördes hårdhetsmätning vid svetsområdet samt en mikrostrukturanalys. Proverna jämfördes för att utreda vilken värmebehandling som var den bästa, för att sedan jämföras mot klassningssällskapens värmebehandlingar.

    Efter svetsning försämrades brottgränsen och duktiliteten, men med hjälp av högre värmebehandlingstemperatur, 500°C och anlöpning, erhölls högre värden. Sträckgränsen ökade något efter svetsning samt med påföljande värmebehandling. Hårdheten i svetsgodset och i grundmaterialet ökade med anlöpningen.

    Endast en förändring inträffade i mikrostrukturen och det var vid anlöpning, då den oönskade betafasen som uppkom efter svetsning, började omvandlas till alfa- och kappafas.

    Högre värmebehandlingstemperaturer förbättrade materialets egenskaper efter svetsning, och anlöpning gjorde även så att brotten uppkom i grundmaterialet istället för kring svetsen.

    De klassningssällskap som har högre värmebehandlingstemperaturer bör då vara mer fördelaktiga än de som säger att värmebehandling inte behövs.

  • 117.
    Fashandi, Hossein
    et al.
    Linköping University.
    Soldemo, Markus
    KTH.
    Weissenrieder, Jonas
    KTH.
    Gothelid, Mats
    KTH.
    Eriksson, Jens
    Linköping University.
    Eklund, Per
    Linköping University.
    Spetz, Anita Lloyd
    Linköping University.
    Andersson, Mike
    Linköping University.
    Applicability of MOS structures in monitoring catalytic properties, as exemplified for monolayer-iron-oxide-coated porous platinum films2016Inngår i: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 344, s. 583-590Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metal Oxide Semiconductor (MOS) capacitor devices comprised of monolayer iron oxide-coated as well as non-coated polycrystalline Pt deposited on oxidized silicon carbide substrates have been fabricated and their usefulness as realistic model systems in catalyst studies development was evaluated. The CO oxidation characteristics of both iron oxide- and non-coated Pt catalysts were investigated using mass spectrometry, monitoring the carbon dioxide production rate for different combinations of carbon monoxide (CO) and oxygen concentrations at various temperatures. Additionally, the output capacitance of the MOS model catalysts was recorded for each individual CO oxidation activity. A low-temperature shift in CO oxidation characteristics for the monolayer-coated compared to the non-coated Pt catalysts was observed, similar to that previously reported for monolayer iron oxide grown on single-crystalline Pt substrates. A strong correlation between the output capacitance of the MOS structures and the CO oxidation characteristics was found for both monolayer- and non-coated model catalysts. Furthermore, the devices exhibit retained MOS electrical output and CO oxidation characteristics as well as an unaffected catalyst surface composition, as confirmed by photoelectron spectroscopy, even after 200 h of continuous model catalyst operation. In addition to the implications on practical applicability of monolayer iron oxide coating on widely used polycrystalline Pt films in real-world catalysts and sensors, the findings also point to new possibilities regarding the use of MOS model systems for in situ characterization, high throughput screening, and tailoring of e.g. catalyst- and fuel-cell-electrode materials for specific applications.

  • 118.
    Fellenius, Malin
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Reduction of vibration transmitted through car seats: A study to reduce test drivers’ whole-body vibrations at Volvo Car Group’s test facility2017Independent thesis Basic level (university diploma), 15 poäng / 22,5 hpOppgave
    Abstract [en]

    Present thesis will concentrate on the attention to reduce the input of whole-body vibrations transmitted to test drivers in durability tests. On behalf of Volvo Cars, the purpose has been to develop a concept solution on the driver's seat. Solving this problem is significant due to test driver’s safety and theirs ergonomically conditions. This project is conducted as a Bachelor of Science thesis for the Innovation & design engineer program at Karlstad University.   

    The assignment is in collaboration with the research and development department Proving Ground Testing Group located outside Borås on their test facility, Hällered Proving Ground (HPG). Where they perform endurance tests on rough roads with complete vehicles. The main goal of this project is to increase the time drivers can actively drive the test cars each day, as well as reduce the exposure of whole-body vibration transmitted to test drivers.  

    The project has been carried out through the Engineering Design Process, which is a substantial model for working with creativity during product development. The report consists of a pre-study in areas like dynamic systems of vibration, ergonomics, previous research, benchmarking and seat structure. This was achieved by identifying the problem areas in an early stage. A number of concepts solutions were evaluated and compared according to implementability and realizability. The final decision was made on a concept, resulted in changing the current foam in the seat. Thereafter, it presents the evaluation of materials throughout the material database CES EduPack and through product research.    

    The last part of the report presents results from laboratory testings and a field test. The objective was to determine which arrangement provided the best isolation throughout different combinations of materials/products and material thicknesses.

    The result of the test showed that an increase of material thickness was the optimal solution. Polyurethane (PUR) foam is best suited for this and factors such as material properties and combination of materials has less or none impact on reducing whole-body vibrations. Therefore, the current foam can maybe be enough, but it needs to be evaluated further. This solution doesn't do any major changes to the cars specification and therefore the cars can be evaluated as before.  

    Further development is to build a prototype with thicker dimensions and implement it in a test vehicle. Subsequently verifying a decrease of exposure from whole-body vibrations, in the form of a real-life test.

    The solution is intended solely for test vehicles at Volvo’s endurance track facility at Hällered. The assignment was to facilitate working conditions for test drivers and make the work more efficient. The thesis purpose was to achieve a sustainable solution, according to Volvo Cars` requirements to reduce exposure from whole-body vibrations and this project is therefore fulfilled. It was important that the solution was easy to implement and can be applied on all platforms, correspondently be used on future test cars from Volvo.  

  • 119.
    Flygare, Mattias
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Svensson, Krister
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Quantifying crystallinity in carbon nanotubes and its influence on mechanical behaviour2019Inngår i: Materials Today Communications, ISSN 2352-4928, Vol. 18, s. 39-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The different fabrication methods that have been developed for making carbon nanotubes will provide materials with different levels of crystallinity. As crystallinity is qualitatively known to have a profound influence on material properties, this raises the need for standardised quantitative analysis. Here we show how transmission electron microscopy can be used to provide quantitative information about effective crystallite sizes in individual nanotubes which we link to the mechanical behaviour of the tubes. The method relies on a thorough analysis of diffraction patterns and a careful extraction of instrumental and sample contributions to the peak shapes. We find that arc-discharge grown tubes have crystallite sizes that are comparable to the circumference of the outer tube walls, while commercial catalytically grown tubes have much smaller crystallites implying that each cylindrical nanotube wall can be thought of as a patchwork of small graphene-like grains. The clear differences in crystallite sizes are then compared to known differences in mechanical behaviour, such as a substantial disparity in stiffness and significantly different behaviours under bending stress.

  • 120.
    Fransson, Christoffer
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap. Karlstads universitet, Institutionen för ingenjörsvetenskap, fysik och matematik.
    Accelerated aging of aluminum alloys2009Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In order to determine storage life for aluminum alloys it is essential to have a good knowledge on the accelerated aging behavior and the mechanical properties that are affected. The selected aluminum alloys are AA2017, AA6082, AA7075 and the study has been focused on their impact toughness and hardness relation to aging beyond peak conditions. To be able to plot the mechanical properties versus aging time and temperature, Differential Scanning Calorimetric runs have been the key to obtain supporting activation energies for a specific transformation. The activation energies have been calculated according to the Kissinger method, plotted in Matlab. Arrhenius correlation has also been applied to predict the natural aging time for long time storage in 30 degrees Celsius. It could be concluded that the results from the mechanical test series show that the constructed Arrhenius 3D method did not meet the expectations to extrapolate constant activation energies down to storage life condition. Scanning electron microscopy together with light optical microscopy analyses show how important it is to apply notches in proper test specimen directions and how precipitates are grown, as it will affect impact toughness and hardness.

    An ending discussion is held to explain how mechanical testing progressed and how other external issues affected the master thesis operations.

  • 121.
    Fredriksson, Gunnel
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Electrical Discharge and How it Affects Tool Steels1994Rapport (Annet vitenskapelig)
  • 122.
    Fredriksson, Gunnel
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Electrical Discharge Machining and its influence on Forming Tools1997Konferansepaper (Fagfellevurdert)
  • 123.
    Fredriksson, Gunnel
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Electrical Discharge Machining and the properties of Tool Steels1996Rapport (Annet vitenskapelig)
  • 124.
    Fredriksson, Gunnel
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Influence of EDM: Post treatments and coatings on mechanical porperties of cold work steels1999Rapport (Annet vitenskapelig)
    Abstract [en]

    This report is a presentation of results from the laboratory tests of the project Electrical Discharge Machining of Tools in Cold Work Applications. Two high speed steels, two cold work ingot cast and forged steels, and one powder metallurgical cold work steel at hardness from 51 to 66 HRc were included in the study. In the first part of the report differences between the various tool steels in how they respond to electrical discharge machining (EDM) are discussed. Surface alterations, defect distributions, static and fatigue strength are included as well as wire and die sinking EDM, both rough and fine. In the second part some post EDM treatments are examined. The effect of tempering and shot peening after EDM on mechanical properties of the tool steel is shown and a comparison of mechanical polishing and electrochemical polishing (ECP) is given. Since cold work tool steels are being used at increasing hardness, the third part is a study where the hardness of two tool steels has been varied in order to see how important this is to the effect of EDM on mechanical properties of the steel. In the last part the combination of EDM, mechanical or electrochemical polishing and thin ceramic surface coatings are studied, one CVD and one PVD coating

  • 125.
    Fredriksson, Gunnel
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Inverkan av temperatur, dielektrikum och elektrodmaterial på ytegenskaperna hos gnistarbetat varmarbetsstål1992Rapport (Fagfellevurdert)
  • 126.
    Fredriksson, Gunnel
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Materialutveckling beträffande formningsverktyg för prototyp och småserier1992Rapport (Annet vitenskapelig)
  • 127.
    Fredriksson, Gunnel
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Metoder för ytjämnhetsmätning1988Rapport (Annet vitenskapelig)
  • 128.
    Fredriksson, Gunnel
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Bergström, Jens
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Hogmark, S.
    Crack Growth in Cold Work Tool Steels - Influence of Surface Condition, Microstructure and Hardness1999Konferansepaper (Fagfellevurdert)
  • 129.
    Fredriksson, Gunnel
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Bergström, Jens
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Hogmark, S
    Fatigue resistance and surface properties of EDMed cold work tool steels1996Konferansepaper (Fagfellevurdert)
  • 130.
    Fredriksson, Gunnel
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Hogmark, S
    Influence of dielectric and temperature in electrical discharge machining of hot work tool steel1996Inngår i: Surface Engineering 11Artikkel i tidsskrift (Fagfellevurdert)
  • 131.
    Frodeson, Stefan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Henriksson, Gunnar
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Berghel, Jonas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Effects of moisture content during densification of biomass pellets, focusing on polysaccharide substances2019Inngår i: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 122, s. 322-330Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, we pelletized four different pure polysaccharides represented cellulose - Avicel, hemicelluloses - locus bean gum mannan and beech xylan and other polysaccharides - apple pectin, and three woods - pine, spruce and beech. All were pelletized at 100° in a single pellet press unit with different level of moisture content from 0 to 15%. The maximal friction force and work required for compression and friction was analyzed together with the pellet density and hardness. The results showed that xylan pellets completely changed in color at 10% moisture content, and this also occurred to some extent with pectin pellets. The color of both Avicel and locus bean gum pellets were not affected at all. During compression, the results showed that water does not affect compression up to 5 kN, while above 5 kN water decreases the energy need for densification of Avicel, locus bean gum and woods. Above 5 kN the energy needs for compressing xylan and pectin increases with increased moisture content. The hardest pellets were produced from Avicel, while locus bean gum produced the weakest pellets. The study concludes that there is a significant difference in how water affects the two hemicelluloses, glucomannan and xylan, during densification.

  • 132.
    Frodeson, Stefan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Henriksson, Gunnar
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Berghel, Jonas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Pelletizing pure biomass substances to investigate the mechanical properties and bonding mechanisms2018Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, nr 1, s. 1202-1222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Solid fuel for heating is an important product, and for sustainability reasons, it is important to replace nonrenewable fuels with renewable resources. This entails that the raw material base for pellet production has to increase. A broader spectrum of materials for pelleting involves variation in biomass substances. This variation, due to lack of knowledge, limits the possibilities to increase the pellet production using new raw materials. In this study, pellets were produced with a single pellet press from 16 different pure biomass substances representing cellulose, hemicellulose, other polysaccharides, protein, lignin, and extractives, and five different wood species, representing softwoods and hardwoods. All pellets were analyzed for the work required for compression and friction, maximum force needed to overcome the backpressure, pellet hardness, solid density, and moisture uptake. The results showed that the hardest pellets were produced from the group of celluloses, followed by rice xylan and larch arbinogalactan. The weakest pellets were from the group of mannans. Conclusions are that the flexible polysaccharides have a greater impact on the pelletizing process than previously known, and that the differences between xylan and glucomannan may explain the difference in the behavior of pelletizing softwoods and hardwoods.

  • 133.
    Gaard, Anders
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Influence of tool microstructure on galling resistance2013Inngår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 57, s. 251-256Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 134.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Aspects on the reactivity of dissolving pulps prior to viscose preparation2012Konferansepaper (Annet vitenskapelig)
  • 135.
    Girlanda, Orlando
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Delamination of paperboard related to offset printing2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The relationship between the behavior of paper during converting operations and the mechanical properties of paper are a fundamental issue for both paper producers and converters. In the attempt to establish these relationships and thus be able to judge the performance of paper, several testing methods have been developed. The major obstacle to achieve this goal is the fact that the stress conditions acting on paper are not always clearly defined neither in converting operations nor during testing. The first step to achieve a better understanding of the problem is to determine the fundamental mechanical properties of paper.Secondly, the stress condition occurring during converting must be investigated. In this respect, the modeling of paperboard represents a fundamental tool, allowing for the definition of the stress acting on paper during virtually every stage of the converting process or testing. These two steps lead to a better choice of the testing methods that are more relevant for each specific converting operation. The studies presented in this thesis investigate the different aspect of out of plane resistance in paper materials, with particular attention to the problem of delamination during offset printing.

  • 136. Girlanda, Orlando
    Experimental Study and Numerical Simulation ofDelamination in Multiply Paperboard during Offset Printing: Licentitatuppsats2004Rapport (Annet vitenskapelig)
    Abstract [en]

    During converting operations and in end-use situations paper has to withstand complex loading conditions, which may in some cases lead to failure. Sometimes paper experiences out-of-plane splitting, commonly denoted by the term delamination.

    This work dealt specifically with the problem of delamination of paperboard occurring in offset printing. The experimental part was mainly focused on the characterization of the mechanical properties of multiply paperboard in the thickness direction. The effects of damage on the strength were initially considered. Furthermore, the delamination position in multiply paperboard was determined using different testing methods.

    The numerical part consisted of a FE analysis of the stress and strain fields in paperboard at the exit of the printing nip. The failure process was studied under imposed displacements conditions with parameterized mechanical properties of board

  • 137. Girlanda, Orlando
    Finit element modelling av ink-tack vid tryckning i offset2004Annet (Annet (populærvitenskap, debatt, mm))
  • 138. Girlanda, Orlando
    Kartongs defektkänslighet i tjockleksriktningen2004Annet (Annet (populærvitenskap, debatt, mm))
  • 139.
    Girlanda, Orlando
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Fellers, Christer
    Delamination Position in Multiply Paperboard Acheived by Different Testing MethodsManuskript (preprint) (Annet vitenskapelig)
  • 140.
    Girlanda, Orlando
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Fellers, Christer
    STFI-Packforsk AB, Stockholm.
    Evaluation of the tensile stress-strain properties in the thickness direction of paper materials2007Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, nr 1, s. 49-56Artikkel i tidsskrift (Fagfellevurdert)
  • 141.
    Girlanda, Orlando
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Fellers, Christer
    STFI-Packforsk AB, Stockholm.
    Modeling of Delamination in Paperboard during Sheet Offset PrintingManuskript (preprint) (Annet vitenskapelig)
  • 142. Girlanda, Orlando
    et al.
    Hallbäck, Nils
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Östlund, S.
    Tryding, J.
    Defect sensitivity and strength of paperboard in the out-of-plane tension and shear2005Inngår i: Journal of Pulp and Paper Science, 31(2), 100-104 (2005)Artikkel i tidsskrift (Fagfellevurdert)
  • 143.
    Glaad, Gustaf
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Pressurizing of high-pressure fuel system forsingle cylinder test cell2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master thesis covers the development of a high-pressure fuel system for compression ignitedfuels such as diesel and diesel-like fuels that will be deployed into a single cylinder test cell at AVLMTC Södertälje, Sweden. The test cell is used by AVL to conduct research and testing of new fuelsfor their customers and this new fuel system will widen the span of fuels able to be tested by theequipment.This thesis focuses on pumping and pressurizing of the fuel, ensuring that all ingoing materialsare non-corrosive in this environment and compatible with the necessary fuels and lastly a safetyanalysis of the system with respect to operator and process safety. Other aspects of the projectsuch as mass flow measurements and fuel conditioning is covered in a sister thesis Mass flowrate measurement of compression ignition fuels in high-pressure stand-alone pump unit for singlecylinder test cell written by C. Aksoy [1].The goal of this thesis project was to deliver a finished manufactured fuel system and if the timeallowed for it, also validate its performance and finally installing and incorporating it into the singlecylinder test cell. The development process started with the writing of a product specificationoutlining the requirements and request on the product in a specification of requirements matrix andrelate these to product properties of the system using a quality function deployment (QFD) matrix.This document was then used as a base for further advancement in developing concepts to solveeach product property and weighing these concepts against each other using Pugh’s matrices. Thechosen concepts were then further developed, a flow chart for the system was developed as well asfuel lines and other supporting components were analyzed and chosen.In the end the high-pressure fuel pump from Scania’s XPI fuel system were chosen as well asa pressure transducer in the HP1000 series from ESI. Within the time frame of this thesis, theproject did not end up getting finished to the degree planned, but due to time constraints werehalted before starting manufacturing of the system. Some minor component choices remained aswell as documentation such as drawings and finalizing the physical layout of the system remained.All information regarding the remaining work needed to finalize the project and deploying thesystem in the test cell were outlined and with more time, the fuel system should fulfill its purposeof allowing testing and research of compression ignited fuel to be possible in the test cell.

  • 144.
    Gunnerek, Rasmus
    Karlstads universitet.
    Fatigue behavior of Ti-6Al-4V alloys manufactured by Selective Laser Melting: Influence of microstructure, surface roughness and surface morphology2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The intention of this thesis is to investigate the fatigue behavior of the Ti-6Al-4V alloy

    manufactured by the relatively new additive manufacturing process called Selective Laser Melting(SLM). SLM

    has been shown the interest from important industries such as the aerospace and biomedical industry for its

    potential of manufacturing lightweight and complex parts to net shape without the need of conventional

    methods like machining.

    Due to the short history of SLM there is little knowledge about how fatigue properties are

    influenced by the manufacturing process. This project aims to add to that knowledge by studying

    how the microstructure, surface roughness and surface morphology influences the fatigue life of

    SLM made Ti-6Al-4V alloys. Fatigue tests are done by conducting 3-point bending tests on SLM

    and conventional samples.

    It was found that the SLM samples only managed 9% of the fatigue life obtained for conventional

    samples. This was assumed to be caused by the poor surface roughness of SLM samples, acting as

    stress concentrations resulting in multiple crack nucleation leading to final fracture. It was also

    found that a surface morphology of 90°, relative to the length of the sample, had worse fatigue life

    compared to 60° and 30° due to the pattern of the sample being perpendicular to the applied load.

  • 145.
    Gåård, Anders
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Effect of Carbide Precipitates in Tool Steel on Material Transfer: A Molecular Dynamics2015Konferansepaper (Fagfellevurdert)
  • 146.
    Gåård, Anders
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Galling in sheet metal forming2008Inngår i: Proceedings of the IDDRG 2008 Conference : Best in class stamping, 16-18 June 2008, Olofström, Sweden., 2008Konferansepaper (Fagfellevurdert)
  • 147.
    Gåård, Anders
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