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  • Ekergård, Boel
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Leijon, Mats
    Uppsala University, Swedish Centre for Renewable Electric Energy Conversion, Department on Engineering Sciences, Uppsala, 751 21, Sweden; Chalmers University of Technology, Department of Electrical Engineering, Gothenburg, 412 96, Sweden .
    Longitudinal end effects in a linear wave power generator2020In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 13, no 2, article id 327Article in journal (Refereed)
    Abstract [en]

    Even though the magnetic circuit of a linear electric machine is very similar to a rotating electric machine, they diverge in one fundamental property. The linear generator is open in both ends, i.e., the magnetic circuit is non-symmetric. This paper investigates and discusses the drawbacks of this non-symmetric design in a linear permanent magnet generator, installed in a wave energy conversion system. A two-dimensional geometry has been utilized for the numerical calculations in a finite element method simulation tool. The results present an increased cogging force and significant core losses in the translator as consequences of the longitudinal ends in the machine. © 2020 by the authors.

  • Dahat, Shubham
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Hurtig, Kjell
    University West, Department of Engineering Science, Division of Welding Technology.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology.
    A Methodology to Parameterize Wire + Arc Additive Manufacturing: A Case Study for Wall Quality Analysis2020In: Journal of Manufacturing and Materials Processing, Vol. 4, no 1, article id 14Article in journal (Refereed)
    Abstract [en]

    The objective of this work was the development of a methodology to parametrize wire + arc additive manufacturing (WAAM), aiming dimension repeatability, and tolerances. Parametrization of WAAM is a difficult task, because multiple parameters are involved and parameters are inter-dependent on each other, making overall process complex. An approach to study WAAM would be through operational maps. The choice of current (Im) and travel speed (TS) for the desirable layer width (LW) determines a parametrization that leads to either more material or less material to be removed in post-operations, which is case study chosen for this work. The work development had four stages. First stage, named ‘mock design’, had the objective of visualizing the expected map and reduce further number of experiments. At the second stage, ‘pre-requisite for realistic operational map’, the objective was to determine the operating limits of TS and Im with the chosen consumables and equipment. Within the ‘realistic operational map’ stage, a design for the experiments was applied to cover a parametric area (working envelope) already defined in the previous stage and long and tall walls were additively manufactured. Actual values of LW (external and effective layer width) were measured and an actual operating envelope was reached. According to the geometry-oriented case study, a surface waviness index (SWindex) was defined, determined, and overlapped in the envelope. It was observed that the walls with parameters near the travel speed limits presented higher SWindex. This operational map was further validated (fourth stage) by selecting a target LW and finding corresponding three parametric set (covering the whole range of operational map) to produce walls on which geometry characterization was carried out. After geometry characterization, obtained LW was compared with the target LW (the maximum values were very tied, with deviations from +0.3 to 0.5 mm), with a SWindex deviation at the order of 0.05. Both results evidence high reproductivity of the process, validating the proposed methodology to parametrize WAAM.

  • Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Welding metallurgy and weldability of superalloys2020In: Metals, ISSN 2075-4701, Vol. 10, no 1, article id 143Article in journal (Refereed)
  • Ferreira Magalhães, Ana Catarina
    et al.
    University West, Department of Engineering Science, Division of Production Systems. University West, Department of Engineering Science, Division of Welding Technology.
    De Backer, Jeroen
    University West, Department of Engineering Science, Division of Production Systems.
    Bolmsjö, Gunnar
    Linnaeus University, Växjö, Sweden.
    Thermal dissipation effect on temperature-controlled friction stir welding: [Efeito da dissipação térmica inducida durante soldadura por friçcão linear sob controlo de temperatura]2019In: Soldagem & Inspeção, ISSN 0104-9224, E-ISSN 1980-6973, Vol. 24, article id e2428Article in journal (Refereed)
    Abstract [en]

    During Friction Stir Welding (FSW) of complex geometries, the thermal dissipation, induced by geometric features or the surrounding environment, may strongly affect the final weld quality. In order to guarantee a consistent weld quality for different conditions, in-process welding parameter adaptation is needed. This paper studies the effect of thermal dissipation, induced by the backing bar thermal conductivity, on the weld temperature and the temperature controller response to it. A new temperature sensor solution, the Tool-Workpiece Thermocouple (TWT) method, was applied to acquire online temperature measurements during welding. An FSW-robot equipped with temperature control, achieved by rotation speed adaptation, was used. AA7075-T6 lap joints were performed with and without temperature control. The cooling rate during welding was register plus macrographs and tensile tests were assessed. The controller demonstrated a fast response promoting the heat input necessary to maintain the set welding temperature. The results demonstrated that temperature control using the TWT method is suitable to achieve higher joint performance and provides a fast setup of optimal parameters for different environments. © 2019, Universidade Federal de Uberlandia. All rights reserved.

  • Ryding, Jennie
    et al.
    University West, Department of Social and Behavioural Studies, Division of Psychology, Pedagogy and Sociology.
    Sorbring, Emma
    University West, Department of Social and Behavioural Studies, Division of Psychology, Pedagogy and Sociology.
    Ny förståelse för forskningsbaserade modeller i familjebehandlande socialt arbete2020In: Barnbladet, ISSN 0349-1994, Vol. XLVI, no 1, p. 12-16Article in journal (Other academic)
    Abstract [sv]

    Evidensbaserad praktik (EBP) har sedan 2000-talet fått en ökad användningsgrad inom människorelaterade yrken, t ex inom verksamheter såsom elevhälsan och socialtjänsten, vars professioner uppmuntras till att arbeta evidensbaserat för att höja graden av kunskapsanvändning och kunskapsutvecklinginom fältet.I den här artikeln kommer vi att beskriva hur förståelsen,inställningen och kunskapen kring EBP och dess relaterade arbetssätt är i stort behov av att problematiseras, då dessa inte sällan bygger på förutfattade meningar och okunskap, vilket i sin tur har resulterat i ett för EBP oförtjänt rykte.

  • Devotta, Ashwin Moris
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Improved finite element modelingfor chip morphology prediction inmachining of C45E steel2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Within the manufacturing of metallic components, machining plays an important role and is of vital significance to ensure process reliability. From a cutting tool design perspective, physics-based numerical modeling that can predict chip morphology is highly necessary to design tool macro geometry. The chip morphology describes the chip shape geometry and the chip curl geometry. Improved chip morphology prediction increases process reliability by improved chip breakability and effective chip evacuation.

    To this end, in this work, a platform is developed to compare a numerical model'schip morphology prediction with experimental results. The investigated cuttingprocesses are orthogonal cutting process and nose turning process. Numerical models that simulate the chip formation process are used to predict the chip morphology accompanied by machining experiments. Computed tomography isused to scan the chips obtained from machining experiments evaluating its ability to capture the chip morphology variation. For the nose turning process, chip curl parameters need to be calculated during the cutting process. Kharkevich model is utilized in this regard for calculating the 'chip in process' chip curl parameters. High-speed videography is used to measure the chip side-flow angle during thecutting process experiments enabling comparison with physics-based model predictions.

    With regards to chip shape predictability, the numerical models that simulate the chip formation process are improved by improving the flow stress models and evaluating advanced damage models. The workpiece material, C45E steel, arecharacterized using Gleeble thermo-mechanical simulator. The obtained flow stress is modeled using phenomenological flow stress models. Existing phenomenological flow stress models are modified to improve their accuracy. The fracture initiation strain component of damage models' influence on the prediction of transition from continuous chip to segmented chip is studied. The flow stress models and the damage models are implemented in the numerical models through FORTRAN subroutines. The prediction of continuous to segmented chip transitions are evaluated for varying rake angles and feed rate ata constant cutting velocity.

    The results from the numerical model evaluation platform show that the methodology provides the framework where an advance in numerical models is evaluated reliably from a 'chip morphology prediction capability' viewpoint forthe nose turning process. The numerical modeling results show that the chip curl variation for varying cutting conditions is predicted qualitatively. The flow stress curves obtained through Gleeble thermo-mechanical simulator show dynamic strain aging presence in specific temperature -strain rate ranges. The results of the phenomenological model modification show their ability to incorporate the dynamic strain aging influence. The modified phenomenological model improvesthe accuracy of the numerical models' prediction accuracy. The flow stress models combined with advanced damage model can predict the transition from continuous to segmented chip. Within damage model, the fracture initiation strain component is observed to influence the continuous chip to segmented chip transition and chip segmentation intensity for varying rake angle and feed rate and at a constant cutting velocity.

  • Carlsson, Jesper
    University West, Department of Social and Behavioural Studies, Division for Educational Science and Languages.
    Gender Bias in Sports Commentary: the CrossFit Games2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This paper examines the phenomenon of gender-biased language of sports commentary in the 2019 CrossFit Games. Three events from the 2019 CrossFit Games were transcribed verbatim and analyzed to answer five hypotheses relating to the overarching question of this paper; Do commentators' talks contain noticeable differences in the mentions of female and male athletes?

    The results of the five hypotheses were mixed; two were confirmed, two were ambiguous, and one was refuted. However, in relation to previous research, the conclusion of this paper was that the phenomenon of gender-biased speech in sports commentary exists in the sport of CrossFit in the year 2019.

    This paper suggests that further research should be carried out in the field of gender-biased commentary in sports and its relation to society and, more specifically the communities of both athletes and commentators.

  • Karlsson Nygren, Camilla
    University West, Department of Social and Behavioural Studies, Division for Educational Science and Languages.
    "Alla sinnen, att man är kreativ med hela kroppen": en forskningsstudie om lärares tankar kring användandet av estetiska uttrycksformer i matematikundervisningen2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Bakgrund: För att elever ska kunna tillämpa sig kunskaperna i matematikundervisningen djupare krävs det att de får lära sig det teoretiska genom praktiska och kreativa övningar. Det krävs enligt forskningen även att elever får diskutera matematik med varandra och att de har lärare och pedagoger som är väl utbildade tillika bekväma med att undervisa traditionell undervisning kombinerat med estetiska uttrycksformer. Därför krävs det även att lärare får kompetensutveckling som gynnar deras arbete med estetiska uttrycksformer i matematikundervisningen. Redan existerande forskning gällande estetiska uttrycksformer inom matematik återfinner man vanligast att den är genomförd i förskolan eller grundskolans äldre år, väldigt sällan återfinns forskning gällande lågstadiet.

    Syfte: Syftet med studien var att undersöka på vilket sätt lärare ansåg sig arbeta med estetiska uttrycksformer i matematikundervisningen, vilka tankar de hade om estetiska uttrycksformer samt att få reda på om de fick kompetensutveckling som de ansåg som tillräcklig för att kunna arbeta med estetiska uttrycksformer så som de själva önskade.

    Metod: Jag har använt mig av en kvalitativ ansats i form av respondentintervjuer av delvis ostrukturerad karaktär. Främst hade jag velat använda mig av endast parintervjuer vilket skulle lett till att antalet respondenter varit få och därför använde jag mig även av enskilda intervjuer.

    Resultat: Resultatet visar att de lärare som medverkat i studien säger sig använda estetiska uttrycksformer i matematikundervisningen i stor utsträckning och jag kan utifrån intervjuerna konstatera att lärarna är väl medvetna om på vilket sätt de använder sig av estetiska uttrycksformer när de planerar undervisningen. Lärarna använder sig av många olika metoder och material för att få kunskaperna att befästas djupare hos eleverna samtidigt som de estetiska uttrycksformerna hjälper lärarna med att kunna se samtliga elevers kunskaper, då estetiska uttrycksformer gör att alla elever får komma till sin rätt. Dock önskar majoriteten av deltagarna mer kompetensutveckling för att kunna få inspiration till nya arbetssätt, till att bli mer bekväma och att kunna utmana sig själva. Enligt lärarna är även tidsbrist en återkommande problemaspekt i yrket då det finns lite tid till att kunna anpassa och ändra undervisningen efter elevernas önskemål eller omvärldens händelser, eller tid till att kunna göra större estetiska projekt då det är antingen för få pedagoger i klassrummet eller för många elever i klasserna.

  • Hanning, Fabian
    et al.
    Chalmers Univ Technol, Dept Ind & Mat Sci, Gothenburg, Sweden.
    Khan, Abdul Khaliq
    Univ Manitoba, Dept Mech Engn, Winnipeg, MB R3T 5V6, Canada.
    Steffenburg-Nordenstroem, Joachim
    GKN Aerosp Sweden AB, S-46138 Trollhattan, Sweden.
    Ojo, Olanrewaju
    Univ Manitoba, Dept Mech Engn, Winnipeg, MB R3T 5V6, Canada.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Investigation of the Effect of Short Exposure in the Temperature Range of 750-950 degrees C on the Ductility of Haynes (R) 282 (R) by Advanced Microstructural Characterization2019In: Metals, E-ISSN 2075-4701, Vol. 9, no 12, article id 1357Article in journal (Refereed)
    Abstract [en]

    A Gleeble-based test method has been developed to study the change in the ductility signature of Haynes (R) 282 (R) during isothermal exposure from 5 s to 1800 s. A temperature range of 750 to 950 degrees C has been used to investigate the effect of age-hardening reactions. Microstructural constituents have been analyzed and quantified using scanning and transmission electron microscopy. Carbides present in the material are identified as primary MC-type TiC carbides, Mo-rich M6C secondary carbides, and Cr-rich M23C6 secondary carbides. Gamma prime (gamma’) precipitates are present in all the material conditions with particle sizes ranging from 2.5 nm to 58 nm. Isothermal exposure causes the growth of gamma’ and development of a grain boundary carbide network. A ductility minimum is observed at 800-850 degrees C. The fracture mode is found to be dependent on the stroke rate, where a transition toward intergranular fracture is observed for stroke rates below 0.055 mm/s. Intergranular fracture is characterized by microvoids present on grain facets, while ductility did not change during ongoing age-hardening reactions for intergranularly fractured Haynes (R) 282 (R).

  • Goel, Sneha
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Bourreau, Kévin
    University of Limoges, Specialty Materials, Limoges 87000, France.
    Olsson, Jonas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Klement, Uta
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg 41296, Sweden.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Can Appropriate Thermal Post-Treatment Make Defect Content in as-Built Electron Beam Additively Manufactured Alloy 718 Irrelevant?2020In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, no 3, article id 536Article in journal (Refereed)
    Abstract [en]

    Electron beam melting (EBM) is gaining rapid popularity for production of complex customized parts. For strategic applications involving materials like superalloys (e.g., Alloy 718), post-treatments including hot isostatic pressing (HIPing) to eliminate defects, and solutionizing and aging to achieve the desired phase constitution are often practiced. The present study specifically explores the ability of the combination of the above post-treatments to render the as-built defect content in EBM Alloy 718 irrelevant. Results show that HIPing can reduce defect content from as high as 17% in as-built samples (intentionally generated employing increased processing speeds in this illustrative proof-of-concept study) to <0.3%, with the small amount of remnant defects being mainly associated with oxide inclusions. The subsequent solution and aging treatments are also found to yield virtually identical phase distribution and hardness values in samples with vastly varying as-built defect contents. This can have considerable implications in contributing to minimizing elaborate process optimization efforts as well as slightly enhancing production speeds to promote industrialization of EBM for applications that demand the above post-treatments.