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  • 151.
    Suárez, Alfredo
    et al.
    Tecnalia R&I, Advanced Manufacturing Department, San Sebastián, 20.009, Spain.
    Veiga, Fernando
    Tecnalia R&I, Advanced Manufacturing Department, San Sebastián, 20.009, Spain.
    Polvorosa, Roberto
    University of the Basque Country, Department of Mechanical Engineering, Spain.
    Artaza, Teresa
    Tecnalia R&I, Advanced Manufacturing Department, San Sebastián, 20.009, Spain.
    Holmberg, Jonas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Swerea IVFAB, Mölndal, 431 22, Sweden.
    López de Lacalle, Luis Norberto
    University of the Basque Country, Department of Mechanical Engineering, Spain.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Trollhättan, Sweden.
    Surface integrity and fatigue of non-conventional machined Alloy 7182019Ingår i: Journal of manufacturing processes, ISSN 1526-6125, Vol. 48, s. 44-50Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Alloy 718 is a high-strength, corrosion-resistant nickel chromium-based superalloy frequently used for applications, such as aerospace, marine, nuclear reactor and chemical industries, due to its outstanding inherent properties such as high strength and corrosion resistance at high temperatures together with good creep behaviour. Although, the use of conventional manufacturing processes is prevalent for their use on Alloy 718, alternative manufacturing technologies are gaining importance. This work compares the effects of alternative manufacturing processes, such as Abrasive water jet (AWJ), Wire Electrical Discharge Machining (WEDM) and ultrasound vibration assisted milling (UVAM) with conventional milling during the manufacture of Alloy 718 parts. Surface integrity, hardness, residual stress and fatigue strength obtained from these machining processes have been examined for cutting alloy 718. Results show that both residual stresses and surface roughness are correlated with fatigue strength. UVAM results shown an improvement on the surface integrity of the final workpiece. AWJ and WEDM show poorer results, further work on post-process technologies or process condition selection must be carry out to establish them as an alternative in Alloy 718 cutting operations.

  • 152.
    Uczak de Goes, Wellington
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Somhorst, Joop
    Volvo Car Corporation, Göteborg, Sweden.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Gupta, Mohit Kumar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Illkova, Kseniya
    Institute of Plasma Physics, Prague, Czech Republic.
    Suspension Plasma-Sprayed Thermal Barrier Coatings for Light-Duty Diesel Engines2019Ingår i: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 28, nr 7, s. 1674-1687Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Demands for improved fuel efficiency and reduced CO2 emissions of diesel engines have been the driving force for car industry in the past decades. One way to achieve this would be by using thermal spraying to apply a thermal insulation layer on parts of the engine’s combustion chamber. A candidate thermal spray process to give coatings with appropriate properties is suspension plasma spray (SPS). SPS, which uses a liquid feedstock for the deposition of finely structured columnar ceramic coatings, was investigated in this work for application in light-duty diesel engines. In this work, different spray processes and materials were explored to achieve coatings with optimized microstructure on the head of aluminum pistons used in diesel engine cars. The functional properties of the coatings were evaluated in single-cylinder engine experiments. The influence of thermo-physical properties of the coatings on their functional properties has been discussed. The influence of different spray processes on coating formation on the complex piston head profiles has been also discussed. The results show that SPS can be a promising technique for producing coatings on parts of the combustion chamber, which can possibly lead to higher engine efficiency in light-duty diesel engines.

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  • 153.
    Fredriksson, Claes
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sustainability of metal powder additive manufacturing2019Ingår i: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 33, s. 139-144Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Additive manufacturing, or 3D-printing, has attracted attention and raised expectations regarding future production and repair of parts, for example, in the aerospace industry. Various techniques have been utilized to deposit metal alloys for components. It has been suggested that this may offer great benefits in terms of sustainability, in particular, new opportunities for lightweighting. There are, however, outstanding questions about sustainability benefits outside of the use phase. In this paper, the material and manufacturing life-cycle stages were investigated for details produced using INCONEL 718. Energy measurements from an ARCAM A2X Electron Beam Melting system are presented and compared to the embodied energy and indirect CO2-emissions of the feedstock as well as to traditional subtractive manufacturing. It is found that both the metal powder production and the additive manufacturing process itself contribute considerably to total energy use and emissions. Ashby’s 5-step method for assessment of sustainable development is used to briefly discuss economic and social implications of additive manufacturing. © 2019 The Authors. Published by Elsevier B.V.

  • 154.
    Mahade, Satyapal
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Zhou, Dapeng
    Institute of Energy and Climate Research (IEK-1), Forschungszentrum Jülich GmbH, Germany.
    Curry, Nicholas
    Treibacher Industrie AG, Austria.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Vassen, Robert
    Institute of Energy and Climate Research (IEK-1), Forschungszentrum Jülich GmbH, Germany.
    Tailored microstructures of gadolinium zirconate/YSZ multi-layered thermal barrier coatings produced by suspension plasma spray: Durability and erosion testing2019Ingår i: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 264, s. 283-294Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work employed an axial suspension plasma spray (SPS) process to deposit two different gadolinium zirconate (GZ) based triple layered thermal barrier coatings (TBCs). The first was a 'layered' TBC (GZ dense/GZ/YSZ) where the base layer was YSZ, intermediate layer was a relatively porous GZ and the top layer was a relatively dense GZ. The second triple layered TBC was a 'composite' TBC (GZ dense/GZ + YSZ/YSZ) comprising of an YSZ base layer, a GZ + YSZ intermediate layer and a dense GZ top layer. The as sprayed TBCs (layered and composite) were characterized using SEM/EDS and XRD. Two different methods (water intrusion and image analysis) were used to measure the porosity content of the as sprayed TBCs. Fracture toughness measurements were made on the intermediate layers (GZ + YSZ layer of the composite TBC and porous GZ layer of the layered TBC respectively) using micro indentation tests. The GZ + YSZ layer in the composite TBC was shown to have a slightly higher fracture toughness than the relatively porous GZ layer in the layered TBC. Erosion performance of the as sprayed TBCs was evaluated at room temperature where the composite TBC showed higher erosion resistance than the layered TBC. However, in the burner rig test conducted at 1400 °C, the layered TBC showed higher thermal cyclic lifetime than the composite TBC. Failure analysis of the thermally cycled and eroded TBCs was performed using SEM and XRD. © 2018 Elsevier B.V.

  • 155.
    Valiente Bermejo, María Asunción
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Teaching Welding with a Flipped Classroom Approach2019Ingår i: Welding Journal, ISSN 0043-2296, Vol. 98, nr 9, s. 42-45Artikel i tidskrift (Refereegranskat)
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  • 156.
    Charles Murgau, Corinne
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Lundbäck, Andreas
    Division of Mechanics of Solid Materials, Luleå University of Technology, 971 81 Luleå, Sweden .
    Åkerfeldt, Pia
    Division of Materials Science, Luleå University of Technology, 971 81 Luleå, Sweden .
    Pederson, Robert
    GKN Aerospace Engine Systems, 461 81 Trollhättan, Sweden .
    Temperature and microstructure evolution in Gas Tungsten Arc Welding wire feed additive manufacturing of Ti-6Al-4V2019Ingår i: Materials, E-ISSN 1996-1944, Vol. 12, nr 21, artikel-id E3534Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Finite Element Method (FEM) is used to solve temperature field and microstructure evolution during GTAW wire feed additive manufacturing process.The microstructure of titanium alloy Ti-6Al-4V is computed based on the temperature evolution in a point-wise logic. The methodology concerning the microstructural modeling is presented. A model to predict the thickness of the Į lath morphology is also implemented. The results from simulations are presented togethe rwith qualitative and quantitative microstructure analysis.

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  • 157.
    Lagrosen, Yvonne
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik.
    The Quality Café: developing the World-Café method for organizational learning by including quality management tools2019Ingår i: Total quality management and business excellence (Online), ISSN 1478-3363, E-ISSN 1478-3371, Vol. 30, nr 13-14, s. 1515-1527Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of this study was to examine the possibility of integrating the World Café method with the affinity diagram tool from quality management. The proposed combination is called the Quality Café. Quality Cafés were carried out at seven spa hotels, one municipality and two student organisations. The cafés were assessed with feedback seminars and questionnaires. The findings show that the method was appreciated by the participants. It contributed to profound dialogues with deepening insights, which stimulated creativity, increased understanding for quality issues and allowed a more holistic view. In addition, the method was experienced as enjoyable and in itself creating coherence. The findings were related to organisational learning theory and several connections were found. The Quality Café should be a useful method for researchers in social science as well as for practitioners. A limitation is that determining the specific effects of the Quality Café method compared to the original World Café is difficult.

  • 158.
    Ferreira Magalhães, Ana Catarina
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS). Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    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]2019Ingår i: Soldagem & Inspeção, ISSN 0104-9224, E-ISSN 1980-6973, Vol. 24, artikel-id e2428Artikel i tidskrift (Refereegranskat)
    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.

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  • 159.
    Ahmadpour, Ali
    et al.
    Amirkabir University of Technology, Department of Mechanical Engineering, Tehran, Iran.
    Noori Rahim Abadi, Seyyed Mohammad Ali
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Thermal-hydraulic performance evaluation of gas-liquid multiphase flows in a vertical sinusoidal wavy channel in the presence/absence of phase change2019Ingår i: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 138, s. 677-689Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Turbulent gas-liquid multiphase flows with and without phase change in a vertical wavy channel are addressed. The multiphase flow field is resolved using the volume of fluid method (VOF), and the flow equations are discretized and numerically solved by the well-known finite volume method. As a multiphase system without mass transfer, air/water flow is considered. It is shown that numerical simulation is well capable of predicting the various multiphase flow regimes ranging from slug to bubbly flows inside wavy channels. Moreover, accurate predictions of overall pressure drop are provided by numerical solutions for various air and water flow rates and the phase shift angle between wavy channel walls. Additionally, condensing flows of refrigerant R134a are simulated inside wavy channels. It is found that for almost all the cases considered in the present study, the convective heat transfer coefficient is higher in wavy channels in respect to straight channels. However, a significant pressure drop penalty is observed especially for high mass fluxes across wavy channels. Therefore, the use of the wavy channels for the enhancement of condensing heat transfer is only advisable for low mass fluxes with the phase shift angle of 180°. © 2019 Elsevier Ltd

  • 160.
    Mandati, Sreenkanth
    et al.
    Centre for Solar Energy Materials, International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur, Hyderabad, Telangana 500005, India ; Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India.
    Dey, Suhash R.
    Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Sarada, Bulusu V.
    Centre for Solar Energy Materials, International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur, Hyderabad, Telangana 500005, India.
    Two-dimensional CuIn1−xGaxSe 2 nano-flakes by pulse electrodeposition for photovoltaic applications2019Ingår i: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 181, s. 396-404Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fabrication of Cu(In,Ga)Se 2 (CIGS) absorber layers containing two-dimensional nano-flake structures using a single stage pulse electrodeposition technique is reported for the first time, wherein CuCl 2 , InCl 3 , GaCl 3 and H 2 SeO 3 are used as precursors in a pH 3 buffer. The method employs tri-sodium citrate as complexing agent. The phenomenon of intrinsic electrochemical dissolution associated with pulse electrodeposition technique is efficiently utilized to obtain CIGS nano-flakes. The presence of tri-sodium citrate and the relaxation time during pulse electrodeposition play crucial role in achieving control over composition and morphology of CIGS films thereby aiding in the formation of nano-flakes. Evolution of nano-flake structures is systematically investigated with the increase in deposition time during pulse electrodeposition. Elemental analysis reveals the stoichiometric composition of nano-flake films while the formation of chalcopyrite phase-pure CIGS is confirmed by XRD and Raman analyses. The bandgap of CIGS nano-flakes is inferred to be about 1.21 eV from Tauc's plot. Mott-Schottky studies unveil the p-type conductivity of the CIGS with a flat-band potential and carrier density values of −0.15 V and 5.2 × 10 16 cm −3 , respectively. Photoelectrochemical characterization of CIGS films affirms their photoactivity and the photoresponse is almost 20 times compared to the traditional planar CIGS films. Nanostructured CIGS films fabricated by low-cost pulse electrodeposition method reduce materials consumption while promising excellent photoresponse and are suitable for photovoltaic and photoelectrochemical applications. © 2019 International Solar Energy Society

  • 161.
    Mahade, Satyapal
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Ruelle, Céline
    ENSIL, Limoges, Franc.
    Curry, Nicholas
    Treibacher Industrie AG, Althofen, Austria.
    Holmberg, Jonas
    Swerea IVF AB, Mölndal, Sweden.
    Björklund, Stefan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Understanding the effect of material composition and microstructural design on the erosion behavior of plasma sprayed thermal barrier coatings2019Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 488, s. 170-184Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, three different TBC compositions comprising of yttria partially stabilized zirconia (8YSZ), yttria fully stabilized zirconia (48YSZ) and gadolinium zirconate (GZ) respectively, were processed by suspension plasma spray (SPS) to obtain columnar microstructured TBCs. Additionally, for comparison, lamellar microstructured, 7YSZ TBC was deposited by air plasma spray (APS) process. SEM analysis was carried out to investigate the microstructure and white light interferometry was used to evaluate the surface morphology of the as-sprayed TBCs. Porosity measurements were made using water intrusion and image analysis methods and it was observed that the SPS-YSZ and APS-YSZ TBCs showed higher porosity content than SPS-GZ and SPS-48YSZ. The as-sprayed TBC variations (APS-YSZ, SPS-YSZ, SPS-GZ, and SPS-48YSZ) were subjected to erosion test. Results indicate that the erosion resistance of APS-YSZ TBC was inferior to the SPS-YSZ, SPS-GZ and SPS-48YSZ TBCs respectively. Among the SPS processed TBCs, SPS-YSZ showed the highest erosion resistance whereas the SPS-48YSZ showed the lowest erosion resistance. SEM analysis of the eroded TBCs (cross section and surface morphology) was performed to gain further insights on their erosion behavior. Based on the erosion results and post erosion SEM analysis, erosion mechanisms for splat like microstructured APS TBC and columnar microstructured SPS TBCs were proposed. The findings from this work provide new insights on the erosion mechanisms of columnar microstructured TBCs and lamellar microstructured TBCs deposited by plasma spray. © 2019 Elsevier B.V.

  • 162.
    Raza, Tahira
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Svensson, Lars-Erik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Varestraint testing of selective laser additive manufactured alloy 718: influence of grain orientation2019Ingår i: Metals, E-ISSN 2075-4701, Vol. 9, nr 10, artikel-id 1113Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of grain orientation on hot cracking susceptibility of selective laser additive manufactured Alloy 718 was investigated by Varestraint testing. Electron backscattered diffraction showed that cracks in heat affected zone (HAZ) of the welded samples occurred in high angle grain boundaries. The extent of HAZ cracking was smaller in samples tested parallel to the elongated grain orientation and larger in samples transverse to the elongated grain orientation. However, for solidification cracking in the weld metal, no significant difference with respect to grain orientation in the base metal was found. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

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  • 163.
    Singh, Sukhdeep
    et al.
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Varestraint weldability testing of cast ATI® 718Plus™: a comparison to cast Alloy 7182019Ingår i: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, nr 2, s. 389-399Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Varestraint testing of the newly developed cast ATI® 718Plus™ after pseudo-HIP (hot isostatic pressing) heat treatments showed that the extent of solidification cracking was independent of the heat treatment condition. The susceptibility towards heat-affected zone (HAZ) liquation cracking was found to be related to the heat treatment dwell time rather than the temperature. The heat treatments at 1120 and 1190 °C for 24 h were the most susceptible to cracking. On the other hand, heat treatments at 1120, 1160 and 1190 °C for 4-h dwell time exhibited the least amount of cracking. The solidification cracking was found to be similar whereas the HAZ liquation cracking was lower for ATI® 718Plus™ after the heat treatment at 1120 and 1190 °C for 4-h dwell time in comparison to cast Alloy 718.

  • 164.
    Mi, Yongcui
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Sikström, Fredrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Nilsen, Morgan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Ancona, Antonio
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS). CNR-IFN Institute for Photonics and Nanotechnologies, Physics Department, via Amendola 173, Bari, 70126, Italy.
    Vision based beam offset detection in laser stake welding of T-joints using a neural network2019Ingår i: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 36, s. 42-49Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents an experimental study where a vision camera integrates coaxially into a laser beam welding tool to monitor beam deviations (beam offset) in laser stake welding of T-joints. The aim is to obtain an early detection of deviations from the joint centreline in this type of welding where the joint is not visible from the top side. A polynomial surface fitting method is applied to extract features that can describe the behaviour of the melt pool. A nonlinear autoregressive with exogenous inputs neural network model is trained to relate eight image features to the laser beam offset. The performance of the presented model is evaluated offline by different welding samples. The results show that the proposed method can be used to guide post weld inspection and has the potential for on-line adaptive control. © 2019 The Author(s). Published by Elsevier B.V.

  • 165.
    Hosseini, Vahid
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Högström, Mats
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Hurtig, Kjell
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Valiente Bermejo, María Asunción
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Stridh, Lars-Erik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Karlsson, Leif
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Wire-arc additive manufacturing of a duplex stainless steel: thermal cycle analysis and microstructure characterization2019Ingår i: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, nr 4, s. 975-987Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The evolution of microstructures with thermal cycles was studied for wire-arc additive manufacturing of duplex stainless steel blocks. To produce samples, arc energy of 0.5kJ/mm and interlayer temperature of 150 degrees C were used as low heat input-low interlayer temperature (LHLT) and arc energy of 0.8kJ/mm and interlayer temperature of 250 degrees C as high heat input-high interlayer temperature (HHHT). Thermal cycles were recorded with different thermocouples attached to the substrate as well as the built layers. The microstructure was analyzed using optical and scanning electron microscopy. The results showed that a similar geometry was produced with 14 layers4 beads in each layerfor LHLT and 15 layers3 beads in each layerfor HHHT. Although the number of reheating cycles was higher for LHLT, each layer was reheated for a shorter time at temperatures above 600 degrees C, compared with HHHT. A higher austenite fraction (+8%) was achieved for as-deposited LHLT beads, which experienced faster cooling between 1200 and 800 degrees C. The austenite fraction of the bulk of additively manufactured samples, reheated several times, was quite similar for LHLT and HHHT samples. A higher fraction of secondary phases was found in the HHHT sample due to longer reheating at a high temperature. In conclusion, an acceptable austenite fraction with a low fraction of secondary phases was obtained in the bulk of wire-arc additively manufactured duplex stainless steel samples (35-60%), where higher austenite fractions formed with a larger number of reheating cycles as well as longer reheating at high peak temperatures (800-1200 degrees C).

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  • 166.
    Eshagh, Mehdi
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Work-integrated learning and Surveying Engineering Education2019Ingår i: VILÄR 5-6 december 2019, University West, Trollhättan: Abstracts / [ed] Kristina Johansson, Trollhättan: University West , 2019, s. 8-8Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Surveying Engineering Education (SEE) programmes are often of three years and the students learn how to model the shape of the Earth's surface by specific instruments, applying mathematics and computer software. They are inherently practically-oriented and majority of their courses contain simulated practical assignments close to the job market. Work-integrated learning (WIL), which is an approach to intentionally involve learners with practical works so that the learn the concepts by using them, is a suitable for SEEs. Different WIL models such as simulated assignment, collaborative learning with help of industry, and cooperative education, are applicable in SEE, which can increase the students' self-confidence, motivation, academic performance, and employability potential in addition to prepare them for working environments. Here, the focus is on the cooperative education in SEE, which is done outside universities. Literatures about WIL lacks attention to SEEs, there is a need for more researches with focus on the state-of-the-actual in this subject rather to see challenges in the work placement of students in business-oriented private sectors. Our literature study and interviews of three graduates from three subsequent graduation years and two students having experience in work placement showed clear supports of the governmental organisations. However, some students experienced difficulties in private companies. The job has been stressful for them and they were sometimes used like labours. Making clear agreements with private companies, clarifying the roles and missions of the students and companies, covering the costs and compensating time are important factors, which need to be considered. Inviting active engineers from companies for performing simulated assignments close to reality at campus will be very helpful for preparing the students for work placement for practical parts of the courses. It is also recommended that cooperative education needs to be performed with a full supervision of university.

  • 167.
    Lagrosen, Yvonne
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik.
    Lagrosen, Stefan
    Linnaeus University, Department of Marketing, Vaxjo, Sweden.
    Workplace health in wellness: a study of Swedish spa-hotels2019Ingår i: International Journal of Quality and Service Sciences, ISSN 1756-669X, E-ISSN 1756-6703, Vol. 11, nr 3, s. 395-408Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: In previous research, quality management practices have been found to be related to better health for employees. Dimensions of health-promoting quality leadership have been defined. The purpose of this study was to identify dimensions of workplace health in the wellness industry and relate them to the dimensions of health-promoting quality leadership. Design/methodology/approach: An empirical study involving seven leading spa-hotels in Sweden has been carried out. The first part of the study consisted of quality cafés carried out at each of the hotels. The quality café is a novel method, which has the World Café-method as its basis, combined with quality management techniques. Based on the findings from the quality cafés, an employee survey was developed. Findings: The findings from the study include a definition of five major health dimensions for the employees, namely, happiness, kinship, respect, physical health conditions and control. The dimensions were found to be statistically consistent and correlated with the self-reported health of the respondents. Research limitations/implications: The findings are related to health promotion theory and the dimensions of health-promoting quality leadership. A framework for health leadership in the wellness industry is proposed. The study was only carried out in one country. Practical implications: The framework and the findings should be useful for managers, particularly in the wellness sector, when designing their operations and health promotion activities. Originality/value: Workplace health in the wellness sector, which is growing worldwide, is very scarcely researched. © 2019, Emerald Publishing Limited.

  • 168.
    Eshagh, Mehdi
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Johansson, Filippa
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Karlsson, Lenita
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Horemuz, Milan
    Royal Institute of Technology, Stockholm, Sweden.
    A case study on displacement analysis of Vasa warship2018Ingår i: Journal of Geodetic Science, ISSN 2081-9919, E-ISSN 2081-9943, Vol. 8, nr 1, s. 43-54Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Monitoring deformation of man-made structures is very important to prevent them from a risk of collapse and save lives. Such a process is also used for monitoring change in historical objects, which are deforming continuously with time. An example of this is the Vasa warship, which was under water for about 300 years. The ship was raised from the bottom of the sea and is kept in the Vasa museum in Stockholm. A geodetic network with points on the museum building and the ship's body has been established and measured for 12 years for monitoring the ship's deformation. The coordinate time series of each point on the ship and their uncertainties have been estimated epoch-wisely. In this paper, our goal is to statistically analyse the ship's hull movements. By fitting a quadratic polynomial to the coordinate time series of each point of the hull, its acceleration and velocity are estimated. In addition, their significance is tested by comparing them with their respective estimated errors after the fitting. Our numerical investigations show that the backside of the ship, having highest elevation and slope, has moved vertically faster than the other places by a velocity and an acceleration of about 2 mm/year and 0.1 mm/year2, respectively and this part of the ship is the weakest with a higher risk of collapse. The central parts of the ship are more stable as the ship hull is almost vertical and closer to the floor. Generally, the hull is moving towards its port and downwards

  • 169.
    Li, Peigang
    et al.
    ESAB AB, Gothenburg, Sweden.
    Hurtig, Kjell
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Högström, Mats
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Svensson, Lars-Erik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Scotti, Americo
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    A contribution to the study of negative polarity in GMA welding2018Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 95, nr 5-8, s. 2543-2553Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    GMAW using the electrode with negative polarity (DCEN) has been frequently suggested as a potential means of increasing production capacity. The objective of this work was to further study the performance of negative polarity in GMAW of carbon steels. In this project phase, bead-on-plate welds were carried out in flat position to assess the effect of different potential shielding gas compositions on bead geometry, finishing and spattering. The characteristics were compared with DCEP at the same current, but depositing the same volume of material per unit of length (more industrial related comparison). The arc length was kept the same by adjusting voltage to reach shortest arcs, yet with suitable non short-circuiting metal transfer mode. An approach to measure bead convexity was also proposed and assessed. The results showed that DCEN is feasible as a means of increasing GMAW production capacity. However, to become DCEN applicable with GMAW, the results suggest an Ar based blend with around 6.5 % of O2 is the most appropriate shielding gas, as much as that there is a demand for a standard electronic controlled power source able to work in constant current mode. 

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  • 170.
    Balachandramurthi Ramanathan, Arun
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Moverare, Johan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Linköping University, Department of Management and Engineering, SE 581 83 Linköping, Sweden.
    Mahade, Satyapal
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Pederson, Robert
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Additive Manufacturing of Alloy 718 via Electron Beam Melting: Effect of Post-Treatment on the Microstructure and the Mechanical Properties.2018Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, nr 1, artikel-id E68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Alloy 718 finds application in gas turbine engine components, such as turbine disks, compressor blades and so forth, due to its excellent mechanical and corrosion properties at elevated temperatures. Electron beam melting (EBM) is a recent addition to the list of additive manufacturing processes and has shown the capability to produce components with unique microstructural features. In this work, Alloy 718 specimens were manufactured using the EBM process with a single batch of virgin plasma atomized powder. One set of as-built specimens was subjected to solution treatment and ageing (STA); another set of as-built specimens was subjected to hot isostatic pressing (HIP), followed by STA (and referred to as HIP+STA). Microstructural analysis of as-built specimens, STA specimens and HIP+STA specimens was carried out using optical microscopy and scanning electron microscopy. Typical columnar microstructure, which is a characteristic of the EBM manufactured alloy, was observed. Hardness evaluation of the as-built, STA and HIP+STA specimens showed that the post-treatments led to an increase in hardness in the range of ~50 HV1. Tensile properties of the three material conditions (as-built, STA and HIP+STA) were evaluated. Post-treatments lead to an increase in the yield strength (YS) and the ultimate tensile strength (UTS). HIP+STA led to improved elongation compared to STA due to the closure of defects but YS and UTS were comparable for the two post-treatment conditions. Fractographic analysis of the tensile tested specimens showed that the closure of shrinkage porosity and the partial healing of lack of fusion (LoF) defects were responsible for improved properties. Fatigue properties were evaluated in both STA and HIP+STA conditions. In addition, three surface conditions were also investigated, namely the 'raw' as-built surface, the machined surface with the contour region and the machined surface without the contour region. Machining off the contour region completely together with HIP+STA led to significant improvement in fatigue performance.

  • 171.
    Neikter, Magnus
    et al.
    Luleå University of Technology, Luleå, Sweden.
    Woracek, R.
    European Spallation Source ERIC, Lund, Sweden. Nuclear Physics Institute of the CAZ, Czech Republic.
    Maimaitiyili, T.
    Paul Scherrer Institute, Villigen, Switzerland; Malmö University, Malmö, Sweden.
    Scheffzük, C.
    Karlsruhe Institute of Technology, Karlsruhe, Germany; Frank Laboratory of Neutron Physics, Dubna, Russian Federation.
    Strobl, M.
    Paul Scherrer Institute, Villigen, Switzerland; Niels Bohr Institute, Copenhagen, Denmark; Nuclear Physics Institute of the CAZ, Czech Republic.
    Antti, Marta-Lena
    Luleå University of Technology, Luleå, Sweden.
    Åkerfeldt, P.
    Luleå University of Technology, Luleå, Sweden.
    Pederson, Robert
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Bjerkén, C.
    Malmö University, Malmö, Sweden.
    Alpha texture variations in additive manufactured Ti-6Al-4V investigated with neutron diffraction2018Ingår i: Additive Manufacturing, ISSN 2214-8604, Vol. 23, s. 225-234Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Variation of texture in Ti-6Al-4V samples produced by three different additive manufacturing (AM) processes has been studied by neutron time-of-flight (TOF) diffraction. The investigated AM processes were electron beam melting (EBM), selective laser melting (SLM) and laser metal wire deposition (LMwD). Additionally, for the LMwD material separate measurements were done on samples from the top and bottom pieces in order to detect potential texture variations between areas close to and distant from the supporting substrate in the manufacturing process. Electron backscattered diffraction (EBSD) was also performed on material parallel and perpendicular to the build direction to characterize the microstructure. Understanding the context of texture for AM processes is of significant relevance as texture can be linked to anisotropic mechanical behavior. It was found that LMwD had the strongest texture while the two powder bed fusion (PBF) processes EBM and SLM displayed comparatively weaker texture. The texture of EBM and SLM was of the same order of magnitude. These results correlate well with previous microstructural studies. Additionally, texture variations were found in the LMwD sample, where the part closest to the substrate featured stronger texture than the corresponding top part. The crystal direction of the α phase with the strongest texture component was [112¯3]. © 2018 Elsevier B.V.

  • 172.
    Agic, Adnan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Analysis of entry phase in intermittent machining2018Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Cutting forces and vibrations are essential parameters in the assessment of a cutting process. As the energy consumption in the machining process is directly affected by the magnitude of the cutting forces it is of vital importance to design cutting edges and select process conditions that will maintain high tool performance through reduced energy consumption. The vibrations are often the cause of poor results in terms of accuracy, low reliability due to sudden failures and bad environmental conditions caused by noise. The goal of this work is to find out how the cutting edge and cutting conditions affect the entry conditions of the machining operation. This is done utilizing experimental methods and appropriate theoretical approaches applied to the cutting forces and vibrations. The research was carried out through three main studies beginning with a force build-up analysis of the cutting edge entry into the workpiece in intermittent turning. This was followed by a second study, concentrated on modelling of the entry phase which has been explored through experiments and theory developed in the first study. The third part was focused on the influence of the radial depth of cut upon the entry of cutting edge into the workpiece in a face milling application. The methodology for the identification of unfavourable cutting conditions is also explained herein. Important insights into the force build-up process help addressing the correlation between the cutting geometries and the rise time of the cutting force. The influence of the nose radius for a given cutting tool and workpiece configuration during the initial entry is revealed. The critical angle i.e. the position of the face milling cutter that results in unfavourable entry conditions has been explained emphasizing the importance of the selection of cutting conditions. Finally, the theoretical methods utilized for the evaluation of the role of cutting edge geometry within entry phase dynamics has been explored. This has revealed the trends that are of interest for selection of cutting conditions and cutting edge design.

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  • 173.
    Mishchenko, Andrii
    et al.
    Federal University of Uberlandia (UFU),Laprosolda-Center for Research and Development of Welding Processes, Uberlândia, Brazil.
    Wu, Leonardo
    Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil.
    da Silva, Vanessa K.
    Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil.
    Scotti, Americo
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV). Federal University of Uberlandia (UFU),Laprosolda-Center for Research and Development of Welding Processes, Uberlândia, Brazil.
    Analysis of residual stresses resulting from the surface preparation for X-ray diffraction measurement2018Ingår i: Journal of the Brazilian Society of Mechanical Sciences and Engineering, ISSN 1678-5878, E-ISSN 1806-3691, Vol. 40, nr 2, artikel-id 94Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is no consensus in the literature on the need to remove preprocessing layers from the material prior to the measurement of residual stresses by X-ray diffractometer. Thus, the purpose of this work was to evaluate the residual stresses induced by material preprocessing and its evolution during the preparation of the surface by electrolytic removal. Sample surfaces were pre-processed by grinding and sandblasting and the resulting residual stresses were measured by X-ray diffractometry. At each removal stage, the evolution of residual stresses, hardness and microstructure of the surface were verified. It was concluded that different preprocessing methods can induce surface residual stresses of either tension or compression, reaching different depths. Removal by electrolytic method of the modified layer has shown itself capable of reducing significantly the magnitude of the residual stresses induced by preprocessing. On the other hand, the depth of deformed grains or surface hardness proved to be incapable of predicting the depth of induced residual stresses. Finally, it was discussed whether or not the layers removed by this method reveal the subsurface stresses and if the removal should take place before or after a second processing.

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  • 174.
    Ekberg, Johanna
    et al.
    Chalmers University of Technology, Department of Materials and Manufacturing Technology,Göteborg, Sweden.
    Klement, Uta
    Chalmers University of Technology, Department of Materials and Manufacturing Technology,Göteborg, Sweden.
    Björklund, Stefan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Analysis of single splats produced by axial suspension plasma spraying2018Ingår i: Surface Engineering, ISSN 0267-0844, E-ISSN 1743-2944, Vol. 34, nr 5, s. 407-411Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Axial suspension plasma spraying (ASPS) is a relatively new, innovative technique with which microstructures have been produced that are similar to the ones produced by electron beam physical vapor deposition. They have a columnar structure and consist of nm- and µm-sized pores. However, so far the formation of the microstructure is not fully understood because fragmentation and vaporisation of the liquid significantly affects the deposition process. Analysis of single splats can provide important information on the phenomena controlling the coating formation process and the final coating properties. Therefore, the present study aims at providing first results of 8 wt-% yttria-stabilised zirconia single splats sprayed onto a steel substrate by use of ASPS. Scanning electron microscopy and atomic force microscopy have been used to characterise the splats with respect to appearance, shape, and size distribution. © 2017 Institute of Materials, Minerals and Mining Published by Taylor & Francis on behalf of the Institute

  • 175.
    Eriksson, Monica
    et al.
    Högskolan Väst, Institutionen för hälsovetenskap, Avdelningen for hälsopromotion och vårdvetenskap.
    Alsén, Pia
    Högskolan Väst, Institutionen för hälsovetenskap, Avdelningen för omvårdnad - avancerad nivå.
    Lycke, Liselott
    Högskolan Väst, Institutionen för ingenjörsvetenskap.
    Tano, Ingrid
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Aronsson, Gunnar
    Stockholms universitet, Stockholm, Sverige.
    ARK: modell för att systematiskt arbeta med hållbart arbetsliv inom universitet och högskola (UoH)2018Ingår i: FALF 2018 - program och abstraktbok / [ed] Per Lindberg, Gävle: University Press , 2018, s. 123-123Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Bakgrund

    Hållbart arbetsliv är idag ledord för arbetslivets förändrade villkor. Inom UoH i Sverige fanns i slutet av 2017 omkring 75 000 anställda varav ca 35 000 inom forskning och undervisning (UKÄ, 2017). Det är en sektor med stor betydelse för samhällsutvecklingen i Sverige. Arbetsmiljön inom sektorn ställer särskilda krav på personalen. Förvånansvärt få studier har gjorts i Sverige om arbetsmiljön för personal inom UoH. Med förebild från Norge implementeras nu för första gången i Sverige en forskningsbaserad (krav-resurs-modellen) och sektorsspecifik ny modell för att systematiskt arbeta med arbetsmiljön, den s.k. Ark-modellen (arbeidsmiljø- og klimaundersøkelser, se figur) vid Högskolan Väst. Arbetsmiljöverkets föreskrift 2015:4 betonar den organisatoriska och sociala arbetsmiljön, vilket väl tillgodoses i denna modell.

    Syfte

    Att systematiskt och långsiktigt arbeta med arbetsmiljön ur ett främjande, förebyggande och rehabiliterande perspektiv på såväl individ- som organisatorisk nivå för att utveckla förhållanden som bidrar till ett hållbart arbetsliv.

    Metod

    Genom KIWEST (Knowledge Intensive Work Environment Survey Target) kartläggs arbetsmiljön utifrån 28 olika dimensioner. Kategorier som belyses är t.ex. sociala, uppgiftsbaserade och organisatoriska resurser samt jobbkrav och tillhörighet till jobbet. Organisatoriska förhållanden mäts med FaktaARK 1 medan genomförda insatser mäts med FaktaARK 2.

    Resultat

    KIWEST sändes till all personal med 20 % anställning eller mer. Utav 539 tillfrågade personer svarade 376, vilket ger en svarsfrekvens på 69,8 %. Resultatet visar att specifikt för sektorn är upplevelsen av tidspress samtidigt som arbetet upplevs som meningsfullt och viktigt. Nu följer analyser, planering, genomförande och utvärdering av insatser på olika nivåer inom högskolan. KIWEST-formuläret sänds till personalen med 3-års intervall. I förbättringsarbetet ingår även att granska och utvärdera genomförandet, därvid ingår även metodutveckling. Förbättringsarbetet sätts in i ett större organisatoriskt perspektiv och är en naturlig del i kvalitetssäkringsprocessen och ledningssystemet. ARK-processen förväntas bidra till teoriutveckling av krav- och resursmodellen samt öka kunskapen om arbetsmiljön inom UoH.

  • 176.
    Nystedt, Patrik
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Öinert, Johan
    Blekinge Institute of Technology, Department of Mathematics and Natural Sciences, Karlskrona, Sweden.
    Pinedo, Héctor
    Universidad Industrial de Santander, Escuela de Matemáticas, Carrera 27 Calle 9, Edificio Camilo Torres Apartado de correos 678, Bucaramanga, Colombia.
    Artinian and noetherian partial skew groupoid rings2018Ingår i: Journal of Algebra, ISSN 0021-8693, E-ISSN 1090-266X, Vol. 503, s. 433-452Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Let alpha = {alpha(g) : Rg-1 -> R-g}(g is an element of mor(G)) be a partial action of a groupoid G on a (not necessarily associative) ring R and let S = R-star alpha G be the associated partial skew groupoid ring. We show that if a is global and unital, then S is left (right) artinian if and only if R is left (right) artinian and R-g = {0}, for all but finitely many g is an element of mor(G). We use this result to prove that if a is unital and R is alternative, then S is left (right) artinian if and only if R is left (right) artinian and R-g = {0}, for all but finitely many g is an element of mor(G). This result applies to partial skew group rings, in particular. Both of the above results generalize a theorem by J. K. Park for classical skew group rings, i.e. the case when R is unital and associative, and G is a group which acts globally on R. We provide two additional applications of our main results. Firstly, we generalize I. G. Connell's classical result for group rings by giving a characterization of artinian (not necessarily associative) groupoid rings. This result is in turn applied to partial group algebras. Secondly, we give a characterization of artinian Leavitt path algebras. At the end of the article, we relate noetherian and artinian properties of partial skew groupoid rings to those of global skew groupoid rings, as well as establish two Maschke-type results, thereby generalizing results by M. Ferrero and J. Lazzarin for partial skew group rings to the case of partial skew groupoid rings.

  • 177.
    Hattinger, Monika
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Eriksson, Kristina M.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Aspects of Knowledge Transformation in Industry-Union-University Collaborations: A study of Work-integrated e-Learning courses target Norwegian industry2018Ingår i: VILÄR Abstraktbok / [ed] Kristina Johansson, Trollhättan: Högskolan Väst , 2018, s. 10-10Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The focus in this study is on knowledge transformation in the workplace following substantial competence initiatives through blended e-learning at the university level. Competence development on academic level is a key factor for industries in times of increased digitalization of manufacturing work. To develop competitive manufacturing requires employees with expert knowledge, which professional organisations need to strengthening. Even if individual employees' motivation for learning is essential, management need to put efforts on competence development and encourage education that, combine theory and practice in forms of work integrated learning. Blended e-learning courses on university level has been successful for supporting such competence development needs, which here is described as work-integrated e-learning, e-WIL. In this study, we explore practitioners' knowledge transformation after their participation in blended e-WIL courses that are designed with industry target content aiming for workplace transformations. Specifically, we focus on the learning efforts versus the management strategies after e-learning initiatives that have an effect on workplace transformations.

    The industry target courses in the case study, are designed in collaboration between an industry-union-university venture of a Norwegian industry network, the Addiscounion and a Swedish university. Six courses are included comprising three knowledge subjects; Logistics and Supply Chain Management, Engineering Tools, and Robotics and Automation. Addisco was the facilitator for engaging industry university collaboration, and stimulated co-creation between industry companies. Data was collected through a longitudinal action research project, comprising six focus group sessions with 113 industry participants during 2015 and 2018. We analysed the company management support of knowledge transformation through the course participants' manifestations of experiences in focus groups, conducted after each course intervention. Overall results show that most participants experience a low management support of knowledge transformation as an engine for workplace transformation, after conducting e-WIL courses. Stimulation of individual motivation and new skills gained were not promoted within the workplace structures. There seem to be a lack of individual competence plans, time for studies, business models and routines, networking and recognition of the individuals' knowledge transformation. Rather, participants claimed their individual responsibilities, and motivation that drives them to further competence development. We therefore argue for stronger management awareness and designed learning models, to develop company strategies that fully appreciate the benefits and new knowledge that industry participants bring back into the workplace after course participation.

  • 178.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Reddy, Liam
    The University of Nottingham, Faculty of Engineering, Nottingham, UK.
    Hussein, Tanvir
    The University of Nottingham, Faculty of Engineering, Nottingham, UK.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings2018Ingår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 132, nr March, s. 170-184Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chlorine-induced corrosion of HVAF-sprayed Ni21Cr and Ni5Al coatings was investigated in 5 vol.% O2 + 500vppm HCl + N2 with and without KCl at 600 °C up to 168 h. Both coatings were protective in the absence of KCl. With KCl, Ni21Cr degraded through a two-stage mechanism: 1) formation of K2CrO4 followed by diffusion of Cl− through the oxide grain boundaries to yield chlorine and a non-protective oxide, and 2) inward diffusion of chlorine though defects in the non-protective oxide, leading to breakaway oxidation. Cl−/Cl2 could not diffuse through the protective alumina scale formed on Ni5Al, hence the corrosion resistance increased.

  • 179.
    Hattinger, Monika
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Co-constructing Expertise: Competence Development through Work-Integrated e-Learning in joint Industry-University Collaboration2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis is inter-disciplinary and proceed from the ongoing challenges of the increased digitalization, automation and robotization that impact the manufacturing industry's emergent need of high-qualified practitioners. Digitalization also challenges universities to open up to external collaboration and to design blended e-learning targeting industry knowledge needs. The studies take up on such challenges and explore inter-organizational collaborations and forms of knowledge construction to strengthen engineering competences integrated inwork in a way that enables manufacturing companies to remain effective and to be prepared for future industrial transformations. The objective is to explore how mutual construction of knowledge emerge through learning activities between multiple actors in a joint industry-university collaborative e-learning practice. The empirical setting is a new type of collaborative course concept developed within the project ProdEx. The project comprise a network of industries and one university in a longitudinal design and implementation process of blended and work-integrated e-learning. This initiative was explored with a collaborative action research approach integrated with five studies, from four perspectives, the industry managers, the practitioners, the research teachers and the course unit. Negotiated knotworking, from cultural-historical activity theory, became a central theoretical concept and a working tool to examine how managers, practitioners and research teachers together negotiated production technology knowledge content and e-learning design towards future workplace transformations. This concept was used to further understand how co-construction of knowledge was developing over time into a richer concept. The results contributes to a wider understanding of how co-construction of knowledge in an e-learning design practice was developing into stronger relations between actors and into more stable courses. Real learning cases and digital labs support theory-practical intertwining of mutual learning of active participation between practitioners and ix research teachers. Initial e-learning technology failures and pedagogical mistakes in the courses were easier to overcome, than issues concerning continuous company support for course participation. Matching industry competence needs with university research fields is continuously challenging. Practitioners' aiming for personal continuous competence development on university level created critical and high-qualitative performances and valuable engagement throughout the process of co-construction of knowledge. The knowledge co-construction became a two-way development, pushing research teachers to active involve and consider practitioners' industry experiences concerning learning content, pedagogical strategies and e-learning forms. While earlier research has discussed the problems of crossing boundaries between industry and university, overall findings show that industry and university actors are crossing boundaries when they mutually co-construct knowledge in an elearningpractice. Co-construction of knowledge entail mutual trust, sideways and interactive learning in a collaborative context. The main contribution suggested in the thesis is that co-constructing expertise entail three levels of activities among actors; to have insight into the purposes and practices of others (relational expertise), the capacity to transform the problems of a practice and together build common knowledge (distributed expertise), and finally the capacity of mutually co-construct knowledge acted upon in practice towards work-integrated transformations (co-constructing expertise).

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  • 180.
    Hattinger, Monika
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Eriksson, Kristina M.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Co-construction of Knowledge in Work-Integrated E-learning Courses in Joint Industry-University Collaboration2018Ingår i: International Journal of Advanced Corporate Learning, ISSN 1867-5565, E-ISSN 1867-5565, Vol. 11, nr 1, s. 10-16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Blended e-learning in higher education targeting company knowledge needs, can support continuous competence development for practitioners in the manufacturing industry. However, university education is traditionally not designed for workplace knowledge needs that strengthen practitioners' learning in everyday work, i.e. work-integrated learning.

    Designing for such learning efforts is even more challenging when the pedagogical strategy is to stimulate practitioners own work experiences as a valuable knowledge source in construction with other peers or teachers. The aim is to explore how engineering practitioners and research teachers mutually co-construct knowledge. In particular, three types of case-based methodologies are examined within a range of industry targeted e-learning courses. The study is part of alongitudinal joint industry-university project. Eleven courses were analyzed through focus group sessions with 110 practitioners from 15 different companies. Results show that 1) Virtual digital cases stimulate high technology learning, but show low collaboration with peers, 2) On-line collaborative negotiation cases stimulate both web conferencing and high interactivity, and 3) Real workplace cases do not stimulate e-learning, but motivate strong work-integrated learning and knowledge expansion.

  • 181.
    Eshagh, Mehdi
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Steinberger, Bernhard
    Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, Germany & Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Postboks 1028 Blindern, Oslo, Norway.
    Tenzer, Robert
    Hong Kong Polytechnic University, Department of Land Surveying and Geo-Informatics, 11 Yuk Chai Rd, Hung Hom, Hong Kong.
    Tassara, Andrés
    Universidad de Concepción, Departamento de Ciencias de la Tierra, Facultad de Ciencias Químicas, Victor Lamas 1290, Concepción, Chile.
    Comparison of gravimetric and mantle flow solutions for sub-lithopsheric stress modeling and their combination2018Ingår i: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 213, nr 2, s. 1013-1028Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Based on Hager and O’Connell’s solution to mantle flow equations, the stresses induced by mantle convection are determined using the density and viscosity structure in addition to topographic data and a plate velocity model. The solution to mantle flow equations requires the knowledge of mantle properties that are typically retrieved from seismic information. Large parts of the world are, however, not yet covered sufficiently by seismic surveys. An alternative method of modeling the stress field was introduced by Runcorn. He formulated a direct relation between the stress field and gravity data, while adopting several assumptions, particularly disregarding the toroidal mantle flow component and mantle viscosity variations. A possible way to overcome theoretical deficiencies of Runcorn’s theory as well as some practical limitations of applying Hager and O’Connell’s theory (in the absence of seismic data) is to combine these two methods. In this study, we apply a least-squares analysis to combine these two methods based on the gravity data inversion constraint on mantle flow equations. In particular, we use vertical gravity gradients from the Gravity field and steady state Ocean Circulation Explorer that are corrected for the gravitational contribution of crustal density heterogeneities prior to applying a localized gravity-gradient inversion. This gravitational contribution is estimated based on combining the Vening Meinesz-Moritz and flexural isostatic theories. Moreover, we treat the non-isostatic effect implicitly by applying a band-limited kernel of the integral equation during the inversion. In numerical studies of modeling, the stress field within the South American continental lithosphere we compare the results obtained after applying Runcorn and Hager and O’Connell’s methods as well as their combination. The results show that, according to Hager and O’Connell’s (mantle flow) solution, the maximum stress intensity is inferred under the northern Andes. Additional large stress anomalies are detected along the central and southern Andes, while stresses under most of old, stable cratonic formations aremuch less pronounced or absent. A prevailing stress-vector orientation realistically resembles a convergent mantle flow and downward currents under continental basins that separate Andean Orogeny from the Amazonian Shield and adjacent cratons. Runcorn’s (gravimetric) solution, on the other hand, reflects a tectonic response of the lithosphere to mantle flow, with the maximum stress intensity detected along the subduction zone between the Nazca and Altiplano plates and along the convergent tectonic margin between the Altiplano and South American plates. The results also reveal a very close agreement between the results obtained from the combined and Hager and O’Connell’s solutions. © The Author(s) 2018. Published by Oxford University Press on behalf of The Royal Astronomical Society.

  • 182.
    Hosseini, Vahid
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV). Innovatum AB., Trollhättan, Trollhättan, Sweden.
    Karlsson, Leif
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Engelberg, D.
    University of Manchester, School of Materials, M13 9PL, Manchester, United Kingdom.
    Wessman, Sten
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Correction to: Time-temperature-precipitation and property diagrams for super duplex stainless steel weld metals (Welding in the World, (2018), 62, 3, (517-533), 10.1007/s40194-018-0548-z)2018Ingår i: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 62, nr 4, s. 893-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Unfortunately due to typesetting mistakes, Tables 4-€“6 have been displayed erroneously in the article. © 2018, International Institute of Welding.

  • 183.
    Haas, Sylvio
    et al.
    Photon Science, DESY, Hamburg, Germany.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Fisk, Martin
    Malmö University, Materials Science and Applied Mathematics, Malmö, Sweden Division of Solid Mechanics, Lund University, Lund, Sweden.
    Park, Jun-Sang
    X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, USA.
    Lienert, Ulrich
    Photon Science, DESY, Hamburg, Germany.
    Correlation of precipitate evolution with Vickers hardness in Haynes® 282® superalloy: In-situ high-energy SAXS/WAXS investigation2018Ingår i: Materials Science & Engineering: B. Solid-state Materials for Advanced Technology, ISSN 0921-5107, E-ISSN 1873-4944, Vol. 11, s. 250-258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this work is to characterize the precipitation kinetics in Haynes® 282® superalloys using in-situ high-energy Small Angle X-ray Scattering (SAXS) together with Wide Angle X-ray Scattering (WAXS). The phases identified by WAXS include γ (matrix), γ′ (hardening precipitates), MC (metallic carbides), and M23C6/M6C (secondary metallic carbides). The γ'-precipitates are spheroids with a diameter of several nanometres, depending on the temperature and ageing time. From the SAXS data, quantitative parameters such as volume fraction, number density and inter-particle distance were determined and correlated with ex-situ Vickers microhardness measurements. The strengthening components associated with precipitates and solid solutions are differentiated using the measured Vickers microhardness and SAXS model parameters. A square root dependence between strengthening attributable to the precipitates and the product of volume fraction and mean precipitate radius is found. The solid solution strengthening component correlates with the total volume fraction of precipitates.

  • 184.
    Javidi Shirvan, Alireza
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Choquet, Isabelle
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Nilsson, Håkan
    Chalmers University of Technology, Department of Mechanics and Maritime Sciences, 412 96 Gothenburg, Sweden..
    Jasak, Hrvoje
    University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 10 000 Zagreb, Croatia..
    Coupling boundary condition for high-intensity electric arc attached on a non-homogeneous refractory cathode2018Ingår i: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 222, s. 31-45Artikel i tidskrift (Refereegranskat)
  • 185.
    Puneet, C.
    et al.
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Valleti, Krishna
    International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    Venu Gopal, A.
    National Institute of Technology, Warangal, India.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW). International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, India.
    CrAlSiN nanocomposite thin films for high-speed machining applications2018Ingår i: Materials and Manufacturing Processes, ISSN 1042-6914, E-ISSN 1532-2475, Vol. 33, nr 4, s. 371-377Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    CrAlSiN nanocomposite thin films with varying film chemistry were developed on tungsten carbide (WC)specimens using cylindrical cathodic arc physical vapor deposition (c-CAPVD) technique. The physical, mechanical, and tribological properties of all the films were comprehensively investigated for arriving at the film chemistry leading to the best properties with respect to mechanical applications. The best tribo-mechanical properties were obtained in films with Cr/(AlþSi) ratio of 1.2. This coating with best properties was translated on to WC drill bits for machining tests. The Al and Si content has shown major influence on the adhesion strength and phase constitution of the films, with a considerable change in residual stress too. The superior properties achieved could be attributed to the formation of an ear-perfect nanocomposite structure, with the crystalline CrAlN phase surrounded by an amorphous Si3N4 phase. The tool life of the coated CrAlSiN tools was investigated during dry machining of EN 24material. In comparison to the tool life of an uncoated tool and a TiAlSiN-coated tool, the best CrAlSiN coatings synthesized in this study performed exceedingly well. The present study clearly demonstrates the advantages of CrAlSiN over other existing similar coatings for high-speed machining.

  • 186.
    Mandati, Sreekanth
    et al.
    Centre for Solar Energy Materials, International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur P. O., Hyderabad, Telangana 500005, India; Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India .
    Dey, Suhash R.
    Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana 502285, India.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Bulusu, Sarada. V.
    Centre for Solar Energy Materials, International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur P. O., Hyderabad, Telangana 500005, India.
    Cu(In,Ga)Se2 Films with Branched Nanorod Architectures Fabricated by Economic and Environmentally Friendly Pulse-Reverse Electrodeposition Route2018Ingår i: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 6, nr 11, s. 13787-13796Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cu(In,Ga)Se2 (CIGS) materials are one of the most promising solar cell technologies owing to their large absorption coefficient and tunable direct bandgap, and they have gained considerable commercial maturity. The study herein puts forward the preparation of nanostructured CIGS films containing branched nanorod architectures, which is reported for the first time. The process employs an economic pulse-reverse electrodeposition technique by utilizing the fundamentals of electro-reduction and oxidation to fabricate nanostructured CIGS and completely avoids conventional energy-intensive high-temperature annealing/selenization step. Comprehensive characterization of nanoarchitectured films reveals the stoichiometric composition and chalcopyrite structure with dominant (112) orientation. Nanostructured CIGS exhibits excellent photoactivity with a photocurrent density of 4.31 mA/cm2 at -0.13 V vs RHE in a liquid junction, which is highest for a bare CIGS film and is attributable to its inherent high interface area and better charge transport properties compared to planar films. The ability to produce such efficient nanostructures using an economic, scalable, sustainable, and eco-friendly approach can considerably reduce fabrication costs compared with existing high-temperature bulk material preparation methods. © 2018 American Chemical Society.

  • 187.
    Ganvir, Ashish
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Design of Suspension Plasma Sprayed Thermal Barrier Coatings2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Thermal barrier coatings (TBCs) are widely used on gas turbine components to provide thermal insulation, which in combination with advanced cooling, can enable the gas turbine to operate at significantly higher temperatures even above the melting temperature of the metallic components. There is a permanent need,mainly due to environmental reasons, to increase the combustion temperature inturbines, hence new TBC solutions are needed. By using a liquid feedstock in thermal spraying, new types of TBCs can be produced. Suspension plasma/flame or solution precursor plasma spraying are examples of techniques that can be utilized for liquid feedstock thermal spraying. This approach of using suspension and solution feedstock, which is an alternative to the conventional solid powder feedstock spraying, is gaining increasing research interest since it has been shown to be capable of producing coatings withsuperior performance. The objective of this research work was to identify relationships between process parameters, coating microstructure, thermal conductivity and lifetime in suspension plasma sprayed TBCs. A further objective was to utilize these relationships to enable tailoring of the TBC microstructure for superior performance compared to state-of-the-art TBC used in industry today, i.e. solid feedstock plasma sprayed TBCs. Different spraying techniques, namely suspension high velocity oxy fuel, solution precursor plasma and suspension plasma spraying (with axial and radial feeding) were explored and compared to solid feedstock plasma spraying. A variety of microstructures, such as highly porous, vertically cracked and columnar, were produced and investigated. It was shown that there are strong relationships between microstructure, thermo-mechanical properties and performance of the coatings. Specifically, axial suspension plasma spraying wasshown as a very promising technique to produce various microstructures as wellas highly durable coatings. Based on the experimental results, a tailored columnar microstructure design for a superior TBC performance is also proposed.

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  • 188.
    Jorge, Vinicius Lemes
    et al.
    Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Alves Santos, Cesar Henrique
    Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Scotti, Fernando Matos
    Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Larquer, Thiago Resende
    Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Mota, Carolina Pimenta
    Instituto Federal de Educação, Ciência e Tecnologia do Triângulo Mineiro – IFTM, Patos de Minas, MG, Brasil.
    Reis, Ruham Pablo
    Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Scotti, Americo
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV). Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Development and Evaluation of Wire Feeding Pulsing Techniques for Arc Welding: Desenvolvimento e Avaliação de Técnicas para Pulsação da Alimentação de Arame em Soldagem a Arco2018Ingår i: Soldagem & Inspeção, ISSN 0104-9224, E-ISSN 1980-6973, Vol. 23, nr 3, s. 326-339Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Applying pulsed wire feeding techniques is one of the new approaches for welding, such as for GTAW and GMAW. However, these techniques invariably require specific feeders and/or welding torches, limiting its implementation due to the high costs of the equipment. Thus, the current work aims to introduce and exploratorily evaluate techniques to pulse the wire feeding that works independently from the feeder and/or torch. The first technique is electromechanically driven, and the second one based on electromagnetics. The effects of amplitude and frequency of the pulsed feeding were evaluated in terms of weld bead formation over plates and of the corresponding electric signals. For GTAW, the pulsed wire feeding is capable of modifying the weld bead and make the metal transfer from the wire to the pool more regular. For GMAW, it was found that the pulsing of the wire feeding can interfere with the process, being capable of turning an irregular globular metal transfer into a regular one, while decreasing the mean current and affecting the bead formation. Overall, it is concluded that pulsed wire feeding can affect the processes, even when made independently from the feeder and torch, opening a field for development of derivative welding technologies.

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  • 189.
    Fahlström, Karl
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW). Swerea KIMAB, Kista, University West, Sweden.
    Blackburn, Jon
    The Welding Institute, Great Britain.
    Karlsson, Leif
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Svensson, Lars-Erik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Effect of Laser Welding Parameters on Porosity of Weldsin Cast Magnesium Alloy AM502018Ingår i: Modern Approaches on Material Science, ISSN 2641-6921, Vol. 1, nr 2, s. 25-32Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pores in the weld metal lower the mechanical properties of the weld. It is therefore important to understand the pore formation mechanisms and find procedures that could reduce porosity. This study focused on laser welding of 3 mm thick magnesium alloy AM50, investigating how different parameters affect porosity formation. Low levels of porosity content were achieved by either increasing the welding speed or using a two-pass welding approach. It was found that higher welding speeds did not allow pores,which were pre-existing from the die-casting process, to have sufficient time to coalesce and expand. In the two-pass welding technique, pores were removed as a result of a degassing process which occurred through the second pass.

  • 190.
    Gruber, H.
    et al.
    Chalmers University of Technology, Department of Industrial and Materials Science, Division of Materials and Manufacture, Gothenburg, SE-412 96, Sweden.
    Karimi Neghlani, Paria
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Hryha, E.
    Chalmers University of Technology, Department of Industrial and Materials Science, Division of Materials and Manufacture, Gothenburg, SE-412 96, Sweden.
    Nyborg, L.
    Chalmers University of Technology, Department of Industrial and Materials Science, Division of Materials and Manufacture, Gothenburg, SE-412 96, Sweden.
    Effect of Powder Recycling on the Fracture Behavior of Electron Beam Melted Alloy 7182018Ingår i: Powder Metallurgy Progress, ISSN 1335-8987, Vol. 18, nr 1, s. 40-48Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Understanding the effect of powder feedstock alterations during multicycle additive manufacturing on the quality of built components is crucial to meet the requirements on critical parts for aerospace engine applications. In this study, powder recycling of Alloy 718 during electron beam melting was studied to understand its influence on fracture behavior of Charpy impact test bars. High resolution scanning electron microscopy was employed for fracture surface analysis on test bars produced from virgin and recycled powder. For all investigated samples, an intergranular type of fracture, initiated by non-metallic phases and bonding defects, was typically observed in the regions close to or within the contour zone. The fracture mode in the bulk of the samples was mainly moderately ductile dimple fracture. The results show a clear correlation between powder degradation during multi-cycle powder reuse and the amount of damage relevant defects observed on the fracture surfaces. In particular, samples produced from recycled powder show a significant amount of aluminum-rich oxide defects, originating from aluminum-rich oxide particulates on the surface of the recycled powder. © 2018 H. Gruber et al., published by Sciendo.

  • 191.
    Segerstark, Andreas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Svensson, Lars-Erik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Ojo, Olanrewaju
    University of Manitoba, Department of Mechanical Engineering,Winnipeg, R3T 5V6, Canada.
    Effect of Process Parameters on the Crack Formation in Laser Metal Powder Deposition of Alloy 7182018Ingår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 49A, nr 10, s. 5042-5050Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cracking in Alloy 718 using laser metal powder deposition has been evaluated in this study. It is found that the material is susceptible to cracking when the laser power is high, the scanning speed is high and the powder feeding rate is low. Almost all the cracks are located close to the center of the deposited wall and propagates in the normal direction to the substrate. Evidence of liquation are found at the cracked surfaces and since all cracks reside in regions which are reheated several times, the cracks are determined to mostlikely be heat affected zone liquation cracks. The influence of respective process parameter was evaluated using a design of experiment approach. It is shown that, when the powder feeding rate is incorporated as avariable, the heat input is not a suitable indicator for the hot cracking susceptibility in laser metal powder deposition of Alloy 718. A combinatory model using the power ratio together with the heat input is therefore proposed.

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  • 192.
    Hosseini, Vahid
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Karlsson, Leif
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Wessman, Sten
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV). Swerea KIMAB AB, P.O. Box 7047, Kista, Sweden.
    Fuertes, Nuria
    Swerea KIMAB AB, P.O. Box 7047, Kista, Sweden.
    Effect of sigma phase morphology on the degradation of properties in a super duplex stainless steel2018Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 11, nr 6, artikel-id 933Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sigma phase is commonly considered to be the most deleterious secondary phase precipitating in duplex stainless steels, as it results in an extreme reduction of corrosion resistance and toughness. Previous studies have mainly focused on the kinetics of sigma phase precipitation and influences on properties and only a few works have studied the morphology of sigma phase and its influences on material properties. Therefore, the influence of sigma phase morphology on the degradation of corrosion resistance and mechanical properties of 2507 super duplex stainless steel (SDSS) was studied after 10 h of arc heat treatment using optical and scanning electron microscopy, electron backscattered diffraction analysis, corrosion testing, and thermodynamic calculations. A stationary arc was applied on the 2507 SDSS disc mounted on a water-cooled chamber, producing a steady-state temperature gradient covering the entire temperature range from room temperature to the melting point. Sigma phase was the major intermetallic precipitating between 630 °C and 1010 °C and its morphology changed from blocky to fine coral-shaped with decreasing aging temperature. At the same time, the average thickness of the precipitates decreased from 2.9 Όm to 0.5 Όm. The chemical composition of sigma was similar to that predicted by thermodynamic calculations when formed at 800-900 °C, but deviated at higher and lower temperatures. The formation of blocky sigma phase introduced local strain in the bulk of the primary austenite grains. However, the local strain was most pronounced in the secondary austenite grains next to the coral-shaped sigma phase precipitating at lower temperatures. Microstructures with blocky and coral-shaped sigma phase particles were prone to develop microscale cracks and local corrosion, respectively. Local corrosion occurred primarily in ferrite and in secondary austenite, which was predicted by thermodynamic calculations to have a low pitting resistance equivalent. To conclude, the influence of sigma phase morphology on the degradation of properties was summarized in two diagrams as functions of the level of static load and the severity of the corrosive environment. © 2018 by the authors.

  • 193.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Hussain, Tanvir
    Univ Nottingham, Fac Engn, Nottingham NG7 2RD, England.
    Huhtakangas, Matti
    MH Engn AB, S-69142 Karlskoga, Sweden.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Effect of SiO2 Dispersion on Chlorine-Induced High-Temperature Corrosion of High-Velocity Air-Fuel Sprayed NiCrMo Coating2018Ingår i: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 74, nr 9, s. 984-1000Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    NiCrMo coatings with and without dispersed SiO2 were deposited using high-velocity air-fuel technique. Thermogravimetric experiments were conducted in 5% O-2 + 500 vppm HCl + N-2 with and without a KCl deposit at 600 degrees C for up to 168 h. The SiO2-containing coating showed lower weight change as a result of formation of a protective and adherent Cr-rich oxide scale. SiO2 decelerated short-circuit diffusion of Cr3+ through scale's defects, e.g., vacancies, and promoted the selective oxidation of Cr to form the protective Cr-rich oxide scale. Furthermore, the presence of SiO2 led to less subsurface depletion of Cr in the coating, and accordingly less corrosion of the substrate. The formed corrosion product on the SiO2-free coating was highly porous, non-adherent, and thick.

  • 194.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Eklund, Johan
    Chalmers University of Technology, Department of Environmental Inorganic Chemistry, 41296 Gothenburg, Sweden.
    Simon, Julien Phother
    Chalmers University of Technology, Department of Environmental Inorganic Chemistry, 41296 Gothenburg, Sweden.
    Liske, Jesper
    Chalmers University of Technology, Department of Environmental Inorganic Chemistry, 41296 Gothenburg, Sweden.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Effect of water vapor on the oxidation behavior of HVAF-sprayed NiCr and NiCrAlY coatings2018Ingår i: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176, Vol. 69, nr 10, s. 1431-1440Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Isothermal oxidation behavior of NiCr and NiCrAlY coatings deposited onto low alloy 16Mo3 steel by high-velocity air fuel (HVAF) process was investigated in 5% O-2+20% H2O+N-2 at 600 degrees C for 168h. Whereas NiCrAlY showed lower mass gain compared to NiCr, both coatings succeeded in maintaining the integrity with the substrate during the exposure without any breakaway oxidation. A thin Cr-rich oxide scale (Cr2O3) formed on NiCr, and a thin mixed oxide scale (Al2O3 with NiCr2O4) formed on NiCrAlY significantly increasing the oxidation protection in the presence of water vapor.

  • 195.
    Mahade, Satyapal
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Curry, Nicholas
    Treibacher Industrie AG, Austria.
    Effect of YSZ thickness on the thermal cyclic fatigue performance of gadolinium zirconate/YSZ double layered TBCs2018Ingår i: Proceedings of the International Thermal Spray Conference, s. 79-83Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal barrier coatings (TBCs) play a vital role in allowing the gas turbine engines to operate at high temperatures. With higher operating temperatures (>1200°C), the standard TBC material, 7-8wt. % Yttria Stabilized Zirconia (YSZ), is susceptible to CMAS (Calcium Magnesium Alumino Silicates) degradation and undesirable phase transformation. New TBC materials such as gadolinium zirconate (GZ) have shown to be capable of overcoming the challenges faced by YSZ. However, GZ has inferior fracture toughness relative to YSZ. In this work, three double layered TBC variations with different GZ and YSZ thickness respectively (400GZ/100YSZ, 250GZ/250YSZ and 100GZ/400GZ respectively, where the prefix numbers represent thickness in urn) were produced by suspension plasma spray (SPS) process. In all the three double layered TBC variations, the overall TBC thickness with GZ as the top layer and YSZ as the base layer was kept the same (500 urn). The objective was to investigate the influence of YSZ thickness on the thermal cyclic fatigue performance of GZ/YSZ double layered TBC. The as sprayed TBCs were characterized by SEM, XRD and porosity measurements and later subjected to thermal cyclic fatigue test at 1100°C. It was observed that the GZ/YSZ double layered TBC with lowest YSZ thickness (400GZ/100YSZ) showed higher thermal cyclic lifetime whereas the TBC with thicker YSZ layer (100GZ/400YSZ) showed lowest thermal cyclic fatigue lifetime. The failure analysis of the thermally cycled TBCs revealed similar failure modes, i.e. spallation of the top coat due to horizontal crack propagation within the thermally grown oxide (TGO). Furthermore, the ceramic top coats in all the three TBC variations after failure showed the widening of column gaps. © 2018 ASM International® All rights reserved.

  • 196.
    Eshagh, Mehdi
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Elastic thickness determination based on Vening Meinesz-Moritz and flexural theories of isostasy2018Ingår i: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 213, nr 3, s. 1682-1692Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Elastic thickness (Te) is one of mechanical properties of the Earth's lithosphere. The lithosphere is assumed to be a thin elastic shell, which is bended under the topographic, bathymetric and sediment loads on. The flexure of this elastic shell depends on its thickness or Te. Those shells having larger Te flex less. In this paper, a forward computational method is presented based on the Vening Meinesz–Moritz (VMM) and flexural theories of isostasy. Two Moho flexure models are determined using these theories, considering effects of surface and subsurface loads. Different values are selected for Te in the flexural method to see by which one, the closest Moho flexure to that of the VMM is achieved. The effects of topographic/bathymetric, sediments and crustal crystalline masses, and laterally variable upper mantle density, Young's modulus and Poisson's ratio are considered in whole computational process. Our mathematical derivations are based on spherical harmonics, which can be used to estimate Te at any single point, meaning that there is no edge effect in the method. However, the Te map needs to be filtered to remove noise at some points. A median filter with a window size of 5° × 5° and overlap of 4° works well for this purpose. The method is applied to estimate Te over South America using the data of CRUST1.0 and a global gravity model.

  • 197.
    Åkerfeldt, Pia
    et al.
    Luleå University of Technology,Division of Materials Science, Luleå, Sweden.
    Hörnqvist Colliander, Magnus
    Chalmers University of Technology, Department of Physics, Göteborg, Sweden.
    Pederson, Robert
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV). Luleå University of Technology,Division of Materials Science, Luleå, Sweden.
    Antti, Marta-Lena
    Luleå University of Technology,Division of Materials Science, Luleå, Sweden.
    Electron backscatter diffraction characterization of fatigue crack growth in laser metal wire deposited Ti-6Al-4V2018Ingår i: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 135, s. 245-256Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By additive manufacturing (AM) there is a feasibility of producing near net shape components in basically one step from 3D CAD model to final product. The interest for AM is high and during the past decade a lot of research has been carried out in order to understand the influence from process parameters on the microstructure and furthermore on the mechanical properties. In the present study laser metal wire deposition of Ti-6Al-4V has been studied in detail with regard to its fatigue crack propagation characteristics. Two specimen orientations, parallel and perpendicular to the deposition direction, have been evaluated at room temperature and at 250 °C. No difference in the fatigue crack growth rate could be confirmed for the two specimen orientations. However, in the fractographic study it was observed that the tortuosity varied between certain regions on the fracture surface. The local crack path characteristic could be related to the alpha colony size and/or the crystallographic orientation. Moreover, large areas exhibiting similar crystallographic orientation were observed along the prior beta grain boundaries, which were attributed to the wide alpha colonies frequently observed along the prior beta grain boundaries. © 2017 Elsevier Inc.

  • 198.
    Karimi Neghlani, Paria
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Electron beam melting of Alloy 718: Influence of process parameters on the microstructure2018Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Additive manufacturing (AM) is the name given to the technology of building 3D parts by adding layer-by-layer of materials, including metals, plastics, concrete, etc. Of the different types of AM techniques, electron beam melting (EBM), as a powder bed fusion technology, has been used in this study. EBM is used to build parts by melting metallic powders by using a highly intense electron beam as the energy source. Compared to a conventional process, EBM offers enhanced efficiency for the production of customized and specific parts in aerospace, space, and medical fields. In addition, the EBM process is used to produce complex parts for which other technologies would be either expensive or difficult to apply. This thesis has been divided into three sections, starting from a wider window and proceeding to a smaller one. The first section reveals how the position-related parameters (distance between samples, height from build plate, and sample location on build plate) can affect the microstructural characteristics. It has been found that the gap between the samples and the height from the build plate can have significant effects on the defect content and niobium-rich phase fraction. In the second section, through a deeper investigation, the behavior of Alloy 718 during the EBM process as a function of different geometry-related parameters is examined by building single tracks adjacent to each other (track-by-track) andsingle-wall samples (single tracks on top of each other). In this section, the main focus is to understand the effect of successive thermal cycling on microstructural evolution. In the final section, the correlations between the main machine-related parameters (scanning speed, beam current, and focus offset) and the geometrical (melt pool width, track height, re-melted depth, and contact angle) and microstructural (grain structure, niobium-rich phase fraction, and primary dendrite arm spacing) characteristics of a single track of Alloy 718 have been investigated. It has been found that the most influential machine-related parameters are scanning speed and beam current, which have significant effects on the geometry and the microstructure of the single-melted tracks.

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  • 199.
    Glorieux, Emile
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Franciosa, Pasquale
    University of Warwick, Warwick Manufacturing Group, CV4 7AL Coventry, UK.
    Ceglarek, Darek
    Warwick Manufacturing Group, University of Warwick, CV4 7AL Coventry, UK.
    End-effector design optimisation and multi-robot motion planning for handling compliant parts2018Ingår i: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 57, nr 3, s. 1377-1390Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The deformation of compliant parts during material handling is a critical issue that can significantly affect the productivity and the parts' dimensional quality. There are multiple relevant aspects to consider when designing end-effectors to handle compliant parts, e.g. motion planning, holding force, part deformations, collisions, etc. This paper focuses on multi-robot material handling systems where the end-effector designs influence the coordination of the robots to prevent that these collide in the shared workspace. A multi-disciplinary methodology for end-effector design optimisation and multi-robot motion planning for material handling of compliant parts is proposed. The novelty is the co-adaptive optimisation of the end-effectors' structure with the robot motion planning to obtain the highest productivity and to avoid excessive part deformations. Based on FEA, the dynamic deformations of the parts are modelled in order to consider these during the collision avoidance between the handled parts and obstacles. The proposed methodology is evaluated for a case study that considers the multi-robot material handling of sheet metal parts in a multi-stage tandem press line. The results show that a substantial improvement in productivity can be achieved (up to 1.9%). These also demonstrate the need and contribution of the proposed methodology.

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  • 200.
    Johansson, Pierre E.C.
    et al.
    Volvo Group Trucks Operations, Gothenburg, 405 08, Sweden; Chalmers University of Technology, Gothenburg, 412 96, Sweden.
    Malmsköld, Lennart
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Fast-Berglund, Åsa
    Chalmers University of Technology, Gothenburg, 412 96, Sweden.
    Moestam, Lena
    Volvo Group Trucks Operations, Gothenburg, 405 08, Sweden.
    Enhancing Future Assembly Information Systems: Putting Theory into Practice2018Ingår i: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 17, s. 491-498Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The manufacturing industry is in a changing state where technology advancements change the mindset of how manufacturing systems will function in the future. Industry 4.0 provides manufacturing companies with new methods for improved decision-making processes and dynamic process control. Despite this ambition, the manufacturing industry is far away from implementing this approach in practice. Assembly information systems will play an even more vital role enabling information transfer from product design to shop floor assembly in the future. To prepare the industry for these changes that are foreseen and for those that are yet to be discovered, a learning factory environment is vital. Such an environment is intended to support the industry during the development of assembly information systems. This paper presents an industrial demonstrator which incorporates well-known methods for improving assembly work stations with the perspective on assembly information systems. These methods are still not widely used in manual assembly intense manufacturing companies. This demonstrator illustrates how established theories can be practically used when designing future assembly information systems. The demonstrator will be used to validate functionalities and requirements for future assembly information systems.

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