Ändra sökning
Avgränsa sökresultatet
1234567 1 - 50 av 867
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Holmberg, Jonas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). RISE IVF AB, Argongatan 30, Mölndal, 431 53, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Trollhättan, 461 81, Sweden.
    Berglund, Johan
    RISE IVF AB, Argongatan 30, Mölndal, 431 53, Sweden.
    Beno, Tomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    A detailed investigation of residual stresses after milling Inconel 718 using typical production parameters for assessment of affected depth2020Ingår i: Materials Today Communications, ISSN 2352-4928, Vol. 24, artikel-id 100958Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Production of superalloy gas turbine parts involves time consuming milling operations typically performed in a sequence from rough to finish milling. Rough milling using ceramic inserts allows high removal rates but causes severe sub-surface impact. A relatively large allowance is therefore left for subsequent cemented carbide milling. With increased knowledge of the affected depth it will be possible to reduce the machining allowance and increase efficiency of the manufacturing process. Milling Inconel 718 using typical production parameters has been investigated using new and worn ceramic and cemented carbide inserts. Residual stresses in a milled slot were measured by x-ray diffraction. Stresses were measured laterally across the slot and below the surface, to study the depth affected by milling. The most important result from this work is the development of a framework concerning how to evaluate the affected depth for a milling operation. The evaluation of a single milled slot shows great potential for determining the optimum allowance for machining. Our results show that the residual stresses are greatly affected by the ceramic and cemented carbide milling; both regarding depth as well as distribution across the milled slot. It has been shown that it is important to consider that the stresses across a milled slot are the highest in the center of the slot and gradually decrease toward the edges. Different inserts, ceramic and cemented carbide, and tool wear, alter how the stresses are distributed across the slot and the affected depth. © 2020 The Authors

  • 2.
    Dahat, Shubham
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Hurtig, Kjell
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Scotti, Americo
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    A Methodology to Parameterize Wire + Arc Additive Manufacturing: A Case Study for Wall Quality Analysis2020Ingår i: Journal of Manufacturing and Materials Processing, ISSN 2504-4494, Vol. 4, nr 1, artikel-id 4010014Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

    Ladda ner fulltext (pdf)
    fulltext
  • 3.
    Hanning, Fabian
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Khan, Abdul Khaliq
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada; Manitoba Institute for Materials, University of Manitoba, Winnipeg, Canada .
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Ojo, Olamrewaju
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Advanced microstructural characterisation of cast ATI 718 Plus-effect of homogenisation heat treatments on secondary phases and repair welding behaviour2020Ingår i: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 64, nr 3, s. 523-533Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of base metal conditions on the weld cracking behaviour of cast ATI 718Plus® is investigated by comparing 4 h and 24 h dwell time pseudo-hip homogenisation heat treatments at 1120, 1160 and 1190 °C with the as-cast microstructure. Scanning electron microscopy (SEM), X-ray diffraction (XRD) on electrolytically extracted powder and transmission electron microscopy (TEM) were used to identify Nb-rich secondary phases in interdendritic areas as the C14 Laves phase and Nb(Ti) MC-type carbides. All homogenisation heat treatments but the 1120 °C 4-h condition dissolve the Laves phase. A repair welding operation was simulated by linear groove multi-pass manual gas tungsten arc welding (GTAW). The Laves phase containing microstructures resulted in lower total crack length for heat affected zone cracking. Constitutional liquation of Nb(Ti) MC-type carbides is observed as a liquation mechanism in Laves-free microstructure, while thick liquid film formation due to the Laves eutectic melting could reduce the formation of weld cracks in microstructures containing the Laves phase.

    Ladda ner fulltext (pdf)
    fulltext
  • 4.
    Hosseini, Vahid
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Hurtig, Kjell
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Karlsson, Leif
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Bead by bead study of a multipass shielded metal arc-welded super-duplex stainless steel2020Ingår i: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present study aims at investigating bead geometry and the evolution of microstructure with thermal cycles in multipass shielded metal arc welding of a V-groove 13-mm type-2507 super-duplex stainless steel (SDSS) plate. The weld consisted of 4 beads produced with arc energies of 0.81-1.06 kJ/mm. The upper beads showed lower base metal (BM) dilution than the first bead. Thermal cycles were recorded with thermocouples, indicating that the cooling rate decreased in the as-deposited weld zone when adding a new bead. Ferrite fraction in the as-welded condition was lower for the upper beads. The austenite grain morphology in reheated passes varied depending on the local peak temperatures and the number of reheating passes. Sigma phase precipitated in a location reheated by the third and fourth passes that was subjected to a critical peak temperature for sigma precipitation. Ferrite content, measured using image analysis and Fisher FERITSCOPE technique, showed that the ferrite fraction moved toward 50/50% in the weld metal with an increasing number of reheating cycles. Finally, a schematic map showing an overview of the microstructure in the multipass SDSS weld was introduced.

  • 5.
    Goel, Sneha
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Bourreau, Kévin
    University of Limoges, Specialty Materials, Limoges 87000, France.
    Olsson, Jonas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Klement, Uta
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg 41296, Sweden.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Can Appropriate Thermal Post-Treatment Make Defect Content in as-Built Electron Beam Additively Manufactured Alloy 718 Irrelevant?2020Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, nr 3, artikel-id 536Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

    Ladda ner fulltext (pdf)
    fulltext
  • 6.
    da Silva, Leandro João
    et al.
    SENAI Innovation Institute for Manufacturing Systems and Laser Processing, Joinville, SC, Brazil; Federal University of Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding,Processes, Uberlandia, MG, Brazil.
    Souza, Danielle Monteiro
    Federal University of Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding,Processes, Uberlandia, MG, Brazil.
    de Araújo, Douglas Bezerra
    Federal University of Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding,Processes, Uberlandia, MG, Brazil.
    Reis, Ruham Pablo
    Federal University of Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding,Processes, Uberlandia, MG, Brazil.
    Scotti, Americo
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV). Federal University of Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding,Processes, Uberlandia, MG, Brazil.
    Concept and validation of an active cooling technique to mitigate heat accumulation in WAAM2020Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 107, nr 5-6, s. 2513-2523Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work aimed at introducing and exploring the potential of a thermal management technique, named as near-immersion active cooling (NIAC), to mitigate heat accumulation in Wire + Arc Additive Manufacturing (WAAM). According to this technique concept, the preform is deposited inside a work tank that is filled with water, whose level rises while the metal layers are deposited. For validation of the NIAC technique, Al5Mg single-pass multi-layer linear walls were deposited by the CMT® process under different thermal management approaches. During depositions, the temperature history of the preforms was measured. Porosity was assessed as a means of analyzing the potential negative effect of the water cooling in the NIAC technique. The preform geometry and mechanical properties were also assessed. The results showed that the NIAC technique was efficient to mitigate heat accumulation in WAAM of aluminum. The temperature of the preforms was kept low independently of its height. There was no measurable increase in porosity with the water cooling. In addition, the wall width was virtually constant, and the anisotropy of mechanical properties tends to be reduced, characterizing a preform quality improvement. Thus, the NIAC technique offers an efficient and low-cost thermal management approach to mitigate heat accumulation in WAAM and, consequently, also to cope with the deleterious issues related to such emerging alternative of additive manufacturing.

  • 7.
    Karimi Neghlani, Paria
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Schnur, Christopher
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Contour design to improve topographical and microstructural characteristics of Alloy 718 manufactured by electron beam-powder bed fusion technique2020Ingår i: Additive Manufacturing, ISSN 2214-8604, Vol. 32, artikel-id 101014Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Additive manufacturing (AM) processes are being frequently used in industry as they allow the manufacture ofcomplex parts with reduced lead times. Electron beam-powder bed fusion (EB-PBF) as an AM technology isknown for its near-net-shape production capacity with low residual stress. However, the surface quality andgeometrical accuracy of the manufactured parts are major obstacles for the wider industrial adoption of thistechnology, especially when enhanced mechanical performance is taken into consideration. Identifying theorigins of surface features such as satellite particles and sharp valleys on the parts manufactured by EB-PBF isimportant for a better understanding of the process and its capability. Moreover, understanding the influence ofthe contour melting strategy, by altering process parameters, on the surface roughness of the parts and thenumber of near-surface defects is highly critical. In this study, processing parameters of the EB-PBF techniquesuch as scanning speed, beam current, focus offset, and number of contours (one or two) with the linear meltingstrategy were investigated. A sample manufactured using Arcam-recommended process parameters (threecontours with the spot melting strategy) was used as a reference. For the samples with one contour, the scanningspeed had the greatest effect on the arithmetical mean height (Sa), and for the samples with two contours, thebeam current and focus offset had the greatest effect. For the samples with two contours, a lower focus offset andlower scan speed (at a higher beam current) resulted in a lower Sa; however, increasing the scan speed for thesamples with one contour decreased Sa. In general, the samples with two contours provided a lower Sa (∼22 %)but with slightly higher porosity (∼8 %) compared to the samples with one contour. Fewer defects were detected with a lower scanning speed and higher beam current. The number of defects and the Sa value for thesamples with two contours manufactured using the linear melting strategy were ∼85 % and 16 %, respectively,lower than those of the reference samples manufactured using the spot melting strategy.

  • 8.
    Gupta, Mohit Kumar
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Li, X-H
    Siemens Turbomachinery AB, Finspang, Sweden.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Kjellman, Björn
    GKN Aerosp, Trollhattan, Sweden.
    Design of high lifetime suspension plasma sprayed thermal barrier coatings2020Ingår i: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 40, nr 3, s. 768-779Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal barrier coatings (TBCs) fabricated by suspension plasma spraying (SPS) have shown improved performance due to their low thermal conductivity and high durability along with relatively low production cost. Improvements in SPS TBCs that could further enhance their lifetime would lead to their widespread industrialisation. The objective of this study was to design a SPS TBC system with optimised topcoat microstructure and topcoat bondcoat interface, combined with appropriate bondcoat microstructure and chemistry, which could exhibit high cyclic lifetime. Bondcoat deposition processes investigated in this study were high velocity air fuel (HVAF) spraying, high velocity oxy fuel spraying, vacuum plasma spraying, and diffusion process. Topcoat microstructure with high column density along with smooth topcoat bondcoat interface and oxidation resistant bondcoat was shown as a favourable design for significant improvements in the lifetime of SPS TBCs. HVAF sprayed bondcoat treated by shot peening and grit blasting was shown to create this favourable design.

  • 9.
    Agic, Adnan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Edge Geometry Effects on Entry Phase by Forces and Vibrations2020Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Intermittent machining is in general strongly related to the large impacts in the entry phase and related vibrations. The influence of the impact forces and vibrations on the cutting process is dependent on workpiece material, structural properties of the tool-workpiece system, cutting edge geometries and cutting parameters. Cutting forces adopt generally a periodic behaviour that gives rise to forced vibrations. In addition, self-induced vibrations may arise because of lowrigidity and insufficient damping in the tool-workpiece system at specific cutting parameters. The ability of the cutting tool to carry the loads during the entry phase and minimize the vibrations is often the key parameter for an effective machining operation.This research work is based on the experiments, analytical studies and modelling. It was carried out through six 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 partly 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 the cutting edge into the workpiece in a face milling application. The methodology for the identification of unfavourable radial depth of cut is also addressed herein. Next, effects of the cutting edge on the vibrations in an end milling application were investigated. This study was related to a contouring operation with the maximum chip thickness in the entry phase when machining steel, ISO P material.

    The results of this work provide some general recommendations when milling this type of workpiece material. After that, the focus was set on the dynamic cutting forces in milling. The force developments over a tooth engagement in milling showed to be strongly dependent on the cutting edge geometry. A significant difference between highly positive versus highly negative geometry was found.

    The implication of this phenomena on the stress state in the cutting edge and some practical issues were analysed. Finally, the role of the helix angle on the dynamic response of a workpiece was investigated. The modelling technique using force simulation and computation of the dynamic response by means of modal analysis was presented. Extensive experimental work was conducted to compare the modelling and experimentally obtained results. The modelling results showed a similar trend as the experimental results. The influence of helix angle on the cutting forces and the dynamic response was explained in detail.The research conducted in this work contributes to the deeper understanding of the influence of the cutting edge geometry and the cutting parameters on the force build up process during the entry phase. The presented studies investigate the force magnitudes, force rates and dynamic behaviour of the tools and workpieces when machining at the challenging entry conditions. The methodologies applied are focused on the physical quantities as forces and vibrations rather than the experimental studies that evaluate tool life. The methods and results of the research work are of great interest for the design of the cutting tools and optimization of the cutting processes.

    Ladda ner fulltext (pdf)
    fulltext
    Ladda ner fulltext (pdf)
    fulltext
  • 10.
    Karimi Neghlani, Paria
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Ålgårdh, Joakim
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). GE Additive | Arcam EBM, Designvägen 2, Mölnlycke, 435 33, Sweden.
    Harlin, P.
    Sandvik Additive Manufacturing, Sandviken, 811 81, Sweden.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Effect of build location on microstructural characteristics and corrosion behavior of EB-PBF built Alloy 7182020Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 106, nr 7-8, s. 3597-3607Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electron beam-powder bed fusion (EB-PBF), a high-temperature additive manufacturing (AM) technique, shows great promise in the production of high-quality metallic parts in different applications such as the aerospace industry. To achieve a higher build efficiency, it is ideal to build multiple parts together with as low spacing as possible between the respective parts. In the EB-PBF technique, there are many unknown variations in microstructural characteristics and functional performance that could be induced as a result of the location of the parts on the build plate, gaps between the parts and part geometry, etc. In the present study, the variations in the microstructure and corrosion performance as a function of the parts location on the build plate in the EB-PBF process were investigated. The microstructural features were correlated with the thermal history of the samples built in different locations on the build plate, including exterior (the outermost), middle (between the outermost and innermost), and interior (the innermost) regions. The cubic coupons located in the exterior regions showed increased level (~ 20 %) of defects (mainly in the form of shrinkage pores) and lower level (~ 30-35 %) of Nb-rich phase fraction due to their higher cooling rates compared to the interior and middle samples. Electrochemical investigations showed that the location indirectly had a substantial influence on the corrosion behavior, verified by a significant increase in polarization resistance (Rp) from the exterior (2.1 ± 0.3 kΩ.cm2) to interior regions (39.2 ± 4.1 kΩ.cm2). © 2020, The Author(s).

    Ladda ner fulltext (pdf)
    fulltext
  • 11.
    Sreekanth, Suhas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Hurtig, Kjell
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Ghassemali, Ehsan
    Jönköping University.
    Effect of Direct Energy Deposition Process Parameters on Single-Track Deposits of Alloy 7182020Ingår i: Metals, E-ISSN 2075-4701, Vol. 10, nr 1, s. 01-16, artikel-id 96Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of three important process parameters, namely laser power, scanning speed and laser stand-off distance on the deposit geometry, microstructure and segregation characteristics in direct energy deposited alloy 718 specimens has been studied. Laser power and laser stand-off distance were found to notably affect the width and depth of the deposit, while the scanning speed influenced the deposit height. An increase in specific energy conditions (between 0.5 J/mm2 and 1.0 J/mm2) increased the total area of deposit yielding varied grain morphologies and precipitation behaviors which were comprehensively analyzed. A deposit comprising three distinct zones, namely the top, middle and bottom regions, categorized based on the distinct microstructural features formed on account of variation in local solidification conditions. Nb-rich eutectics preferentially segregated in the top region of the deposit (5.4–9.6% area fraction, Af) which predominantly consisted of an equiaxed grain structure, as compared to the middle (1.5–5.7% Af) and the bottom regions (2.6–4.5% Af), where columnar dendritic morphology was observed. High scan speed was more effective in reducing the area fraction of Nb-rich phases in the top and middle regions of the deposit. The <100> crystallographic direction was observed to be the preferred growth direction of columnar grains while equiaxed grains had a random orientation.

    Ladda ner fulltext (pdf)
    fulltext
  • 12.
    Zafer, Yunus Emre
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap.
    Goel, Sneha
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Ganvir, Ashish
    Research & Technology, Department of Process Engineering, GKN Aerospace Engine Systems AB, 461 81 Trollhättan, Sweden.
    Jansson, Anton
    Örebro University, School of Science and Engineering, 701 82 Örebro, Sweden.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Encapsulation of Electron Beam Melting Produced Alloy 718 to Reduce Surface Connected Defects by Hot Isostatic Pressing2020Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, nr 5, artikel-id 1226Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Defects in electron beam melting (EBM) manufactured Alloy 718 are inevitable to some extent, and are of concern as they can degrade mechanical properties of the material. Therefore, EBM-manufactured Alloy 718 is typically subjected to post-treatment to improve the properties of the as-built material. Although hot isostatic pressing (HIPing) is usually employed to close the defects, it is widely known that HIPing cannot close open-to-surface defects. Therefore, in this work, a hypothesis is formulated that if the surface of the EBM-manufactured specimen is suitably coated to encapsulate the EBM-manufactured specimen, then HIPing can be effective in healing such surface-connected defects. The EBM-manufactured Alloy 718 specimens were coated by high-velocity air fuel (HVAF) spraying using Alloy 718 powder prior to HIPing to evaluate the above approach. X-ray computed tomography (XCT) analysis of the defects in the same coated sample before and after HIPing showed that some of the defects connected to the EBM specimen surface were effectively encapsulated by the coating, as they were closed after HIPing. However, some of these surface-connected defects were retained. The reason for such remnant defects is attributed to the presence of interconnected pathways between the ambient and the original as-built surface of the EBM specimen, as the specimens were not coated on all sides. These pathways were also exaggerated by the high surface roughness of the EBM material and could have provided an additional path for argon infiltration, apart from the uncoated sides, thereby hindering complete densification of the specimen during HIPing.

    Ladda ner fulltext (pdf)
    fulltext
  • 13.
    Glorieux, Emile
    et al.
    WMG, University of Warwick, Coventry, CV4 7AL, United Kingdom.
    Parthasarathy, Prithwick
    ISolve Technologies, Chennai, 600018, India.
    Svensson, Bo
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Danielsson, Fredrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Energy model for motion planning of 2D-belt press line tending robots2020Ingår i: International Journal of Manufacturing Research, ISSN 1750-0591, Vol. 15, nr 1, s. 52-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A current trend in production is to reduce energy consumption where possible not only to lower the cost but also to be a more energy efficient entity. This paper presents an energy model to estimate the electrical energy consumption of 2D-belt robots used for material handling in multi-stage sheet metal press lines. An estimation of the energy consumption is computed by the proposed energy model based on the robot components’ specifications, the robot path and trajectory. The proposed model can predict the energy consumption offline by simulation, and thus, before installation, avoiding the need for physical experiments. It is demonstrated that it can be used for predicting potential energy reductions achieved by optimising the motion planning. Additionally, it is also shown how to investigate the energy saving achieved by using mechanical brakes when the robot is idle. This effectively illustrates the usefulness of the proposed energy model. © 2020 Inderscience Enterprises Ltd.

  • 14.
    Johansson, Mikael
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW). Sandvik Materials Technology, SE-811 81 Sandviken, Sweden.
    Stenvall, Peter
    Sandvik Materials Technology, SE-811 81 Sandviken, Sweden.
    Karlsson, Leif
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Evaluation of test results and ranking criteria for Varestraint testing of an austenitic high-temperature alloy2020Ingår i: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 64, s. 903-912Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Varestraint testing is commonly used to evaluate hot cracking susceptibility of materials. In this paper, the dependence of operators and evaluation technique on test results is studied for a high-temperature austenitic stainless steel (UNS S31035). Samples were tested at six different strain levels ranging from 0.7 to 3.8%. Four different operators evaluated the same samples following the same instructions on how to measure the cracks manually in an optical microscope at x 25 magnification. The largest variation among operators evaluation was found for low strain levels where small and few cracks were found. In addition, one of the four operators used image analysis to evaluate the samples at x 50 magnification. The average total crack length and total number of cracks in fusion zone and heat-affected zone were approximately 1.5 times higher when using image analysis compared with manual evaluation. Image analysis at x 50 made it possible to detect smaller cracks compared with manual evaluation at x 25 magnification, contributing to an increased number of cracks detected. The maximum crack length using image analysis at x 50 was similar to manual evaluation made at x 25 magnification and was the criterion that showed the least variation in this study. However, further comparisons using other magnifications are needed to verify the agreement between manual evaluation and image analysis found in this study. An advantage with evaluation using image analysis is that it provides traceable results. A harmonized standard for Varestraint testing, and especially for evaluation, would decrease the variation among operators and laboratories.

    Ladda ner fulltext (pdf)
    fulltext
  • 15.
    Neikter, Magnus
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Luleå University of Technology, Division of Materials Science, Luleå, 97181, Sweden;Chalmers University of Technology, .
    Colliander, Magnus
    Chalmers University of Technology,Department of Applied Physics, Göteborg, 41296, Sweden.
    de Andrade Schwerz, C.
    GKN Aerospace Engine Systems, Trollhättan, 46138, Sweden.
    Hansson, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). GKN Aerospace Engine Systems, Trollhättan, 46138, Sweden.
    Åkerfeldt, Pia
    Luleå University of Technology, Division of Materials Science, Luleå, 97181, Sweden.
    Pederson, Robert
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Antti, Marta-Lena
    Luleå University of Technology, Division of Materials Science, Luleå, 97181, Sweden.
    Fatigue crack growth of electron beam melted TI-6AL-4V in high-pressure hydrogen2020Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, nr 6, artikel-id 1287Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Titanium-based alloys are susceptible to hydrogen embrittlement (HE), a phenomenon that deteriorates fatigue properties. Ti-6Al-4V is the most widely used titanium alloy and the effect of hydrogen embrittlement on fatigue crack growth (FCG) was investigated by carrying out crack propagation tests in air and high-pressure H2 environment. The FCG test in hydrogen environment resulted in a drastic increase in crack growth rate at a certain DK, with crack propagation rates up to 13 times higher than those observed in air. Possible reasons for such behavior were discussed in this paper. The relationship between FCG results in high-pressure H2 environment and microstructure was investigated by comparison with already published results of cast and forged Ti-6Al-4V. Coarser microstructure was found to be more sensitive to HE. Moreover, the electron beam melting (EBM) materials experienced a crack growth acceleration in-between that of cast and wrought Ti-6Al-4V. © 2020 by the authors.

    Ladda ner fulltext (pdf)
    fulltext
  • 16.
    Devotta, Ashwin Moris
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Improved finite element modelingfor chip morphology prediction inmachining of C45E steel2020Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Populärvetenskaplig Sammanfattning

    Bearbetning är en 150-årig tillverkningsprocess som återfinns antingen direkt eller indirekt i nästan allt som tillverkas. I dagsläget med den snabba omställning motmer digitala arbetssätt riskerar allt som inte digitaliseras med stor sannolikhet att bli kvarlämnat. Två aspekter mot digitaliseringen av skärande bearbetningsprocesser har genomförts i detta arbete. Den första var en utvärdering av befintliga metoder och utvecklingen av nya metoder för att digitalisera komplexa spångeometrier som återfinns i bearbetningsprocessen, vilket inte tidigare gjorts. Nästa steg är att fånga fysiken som är involverad i en skärprocess för att kunna simulera denna med högre noggrannhet. I denna del av arbetet har inriktats till att urskilja små förändringar i ingångsförhållandena i dess relation till spånformning.

    En spånans ytstruktur kan vara antingen slät eller korrugerad. Att veta vilken spånform som kommer att skapas ger oss förmågan att bättre kontrollera bearbetningsprocessen. I det genomförda arbetet har det skapats förbättrande materialmodeller som möjliggör en ökad noggrannhet vad gäller möjligheten att simulera spånformen vid skärande bearbetning. En stor del av arbetet här harägnats åt en ökad förståelse av ett materials uppträdande, i detta fall stål, vid skärande bearbetning. Detta har skett genom omfattande materialtestning där testresultaten har presenterats i form av matematiska ekvationer i de numeriska modellerna. Övriga metoder som har används för att skapa dessa digitala spånor inkluderar datortomografi, höghastighetsvideografi och matematiska modeller. När dessa kombineras med datorgrafik kan man erhålla numeriska modeller för att simulera skärande bearbetning.

    Resultatet av denna förbättring av befintliga numeriska modeller är förmågan att se påverkan av hur små förändringar i skärverktygets geometri kan påverka formen på den av skärprocessen skapade spånan. Sammantaget kan resultatet av den genomförda forskningen bidra till att skapa ett obrutet virtuellt arbetssätt vidproduktutveckling av skärande verktyg.

    Ladda ner fulltext (pdf)
    fulltext
    Ladda ner fulltext (pdf)
    fulltext
  • 17.
    Kisielewicz, Agnieszka
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sikström, Fredrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Christiansson, Anna-Karin
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Palumbo, Gianfranco
    CNR-IFN Institute for Photonics and Nanotechnologies, Physics Department, Bari, Italy.
    Ancona, Antonio
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS). CNR-IFN Institute for Photonics and Nanotechnologies, Physics Department, Bari, Italy.
    In-process spectroscopic detection of chromium loss during Directed Energy Deposition of alloy 7182020Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 186, artikel-id 108317Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, a fast optical spectrometer was used to monitor the Directed Energy Deposition (DED) process, during the deposition of Alloy 718 samples with different laser power, thus different energy inputs into the material. Spectroscopic measurements revealed the presence of excited Cr I atoms in the plasma plume. The presence was more apparent for the samples characterized by higher energy input. The Cr depletion from these samples was confirmed by lower Cr content detected by Energy-Dispersive X-ray Spectroscopy (EDS) analysis. The samples were also characterized by higher oxidation and high-temperature corrosion rates in comparison to the samples produced with low energy input. These results prove the applicability of an optical emission spectroscopic system for monitoring DED to identify process conditions leading to compositional changes and variation in the quality of the built material.

  • 18.
    K, Divya Nath
    et al.
    SCMS School of Engineering & Technology, Karukutty, Ernakulam, Kerala 683582, India.
    Ramanathan, Prabhu K.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Interfaced Circuit using a non- destructive method for Moisture Measurement2020Ingår i: Microprocessors and microsystems, ISSN 0141-9331, E-ISSN 1872-9436, Vol. 73, artikel-id 102951Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Analysing the moisture in stored products like harvested cereal grains and their products, peas, beans, oil-seeds, copra, cocoa beans, spices etc. is very much important to avoid the fungi growth. Moisture can be present in grain in more than one state, i.e. as bound, adsorbed or absorbed water. A designed, integrated circuit was interfaced with personal computer to measure the capacitance which in turn help to calculate the moisture content of rice. The interfaced circuit was tested by measuring the capacitance of different ceramic capacitor. This technique is fast, reliable, accurate and gives hundred set of readings in few seconds. Moisture contents are measured in percentage. The error correction was done with the help of mat - lab programming.

  • 19.
    Gupta, Mohit Kumar
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Musalek, Radek
    Department of Materials Engineering, Institute of Plasma Physics of Czech Academy of Sciences, Prague, Czech Republic.
    Tesar, Tomas
    Department of Materials Engineering, Institute of Plasma Physics of Czech Academy of Sciences, Prague, Czech Republic.
    Microstructure and failure analysis of suspension plasma sprayed thermal barrier coatings2020Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 382, artikel-id 125218Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Improvements in performance of thermal barrier coatings (TBCs) used in gas turbine engines are highly desired as they can result in higher engine efficiency leading to reduction of harmful emissions. Suspension plasma spraying (SPS) has been shown to produce high performance porous columnar TBCs that can provide low thermal conductivity and high durability. Apart from the topcoat microstructure and chemistry, the lifetime of TBCs is also dependent on bondcoat microstructure and chemistry, and topcoat-bondcoat interface roughness. In case of SPS TBCs, the interface roughness can significantly affect the columnar topcoat microstructure, thus making the bondcoat selection even more crucial. In this work, six different sets of samples were produced by fabricating bondcoats with conventional atmospheric plasma spraying (APS), high velocity air fuel (HVAF) spraying, or hybrid water/argon stabilised plasma (WSP-H) gun, and SPS topcoats using axial SPS (ASPS) or WSP-H spray guns. The objective of this study was to investigate the influence of varying the topcoat microstructure, bondcoat microstructure and topcoat-bondcoat interface roughness on oxide growth behaviour and thermal cyclic fatigue (TCF) lifetime of SPS TBCs. Samples after failure were investigated to understand the failure mechanism in each case. The results showed that changing the bondcoat spray process and spray gun resulted in significant variation in bondcoat surface roughness. A porous columnar structure was created by the ASPS process, while a feathery columnar structure was created by the WSP-H spray gun in this study. Samples with WSP-H bondcoat resulted in highest cyclic lifetime in this study, despite showing severe oxidation of the bondcoat as compared to APS and HVAF bondcoats. This result could be attributed to the very high bondcoat surface roughness in these samples that could have resulted in improved mechanical anchoring of the topcoat. The HVAF bondcoats showed the best oxidation resistance in this study. © 2019 Elsevier B.V.

  • 20.
    Musalek, Radek
    et al.
    Department of Materials Engineering, Institute of Plasma Physics CAS, v.v.i, Prague, Czechia.
    Tesar, Tomas
    Department of Materials Engineering, Institute of Plasma Physics CAS, v.v.i, Prague, Czechia.
    Medricky, Jan
    Department of Materials Engineering, Institute of Plasma Physics CAS, v.v.i, Prague, Czechia.
    Lukac, Frantisek
    Department of Materials Engineering, Institute of Plasma Physics CAS, v.v.i, Prague, Czechia.
    Chraska, Tomas
    Department of Materials Engineering, Institute of Plasma Physics CAS, v.v.i, Prague, Czechia.
    Gupta, Mohit Kumar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Microstructures and Thermal Cycling Properties of Thermal Barrier Coatings Deposited by Hybrid Water-Stabilized Plasma Torch2020Ingår i: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 29, nr 3, s. 444-461Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hybrid water-stabilized plasma (WSP-H) torches provide high-enthalpy plasma which may be utilized for high-throughput and yet economical spraying of coatings from powders, suspensions, and solutions. It was previously demonstrated that microstructures and functional properties of the WSP-H coatings may be tailored to a wide extent for new applications, namely those requiring high coating thickness and/or coating of large components. In this study, applicability potential of WSP-H technology for spraying of novel thermal barrier coatings (TBCs) is demonstrated. WSP-H technology was used for spraying of yttria-stabilized zirconia (YSZ) top-coats from powder, suspension, and solution. Yttria content in the top-coat feedstock was 7-8 wt.%. In addition, gadolinium zirconate (Gd2Zr2O7-GZO) was sprayed from suspension for comparison. NiCrAlY bond-coat was also deposited by WSP-H, and Hastelloy-X alloy was used as substrate material. Microstructure, phase composition, and endurance of the deposited coatings in thermal cycling fatigue (TCF) test and during high-temperature short-term annealing were evaluated. All coatings showed excellent high-temperature stability and TCF resistance withstanding more than 650 cycles, surpassing some of the currently commercially used TBCs. Lifetime of the TBC with columnar top-coat deposited from YSZ suspension exceeded even more than 900 cycles.

  • 21.
    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).
    Mind the Gap: a Collaborative Competence e-Learning Model between University and Industry2020Ingår i: Proceedings of the 53rd Hawaii International Conference on System Sciences Jan 07 - 10, 2020 a Maui, Hawaii, United States of America., 2020, s. 79-88Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article departure from the effects that interorganizational collaboration brings for the participating partners, specifically from design-related activities of e-learning courses and co-production. There search focus is on critical factors for interorganizational collaborative e-learning and coproduction between university and industry. We describe the process of a six-year longitudinal collaborative action research project including six cases and three phases, initialization, implementationand dissemination. The analysis is conducted from a multi-stakeholder perspective; managers, teachers,and practitioners. Overall aim is to reach for a sustainable collaborative competence e-learning model(CCeM) that will increase industrial employees' competences. Main contribution is that co-production of knowledge entails three levels of activities among actors; to have insight into the purposes and practicesof others, the capacity to transform the problems of a practice and together build common knowledge and finally the capacity of mutually co-produce knowledge acted upon in practice towards transformations in the workplace.

    Ladda ner fulltext (pdf)
    fulltext
  • 22.
    Joshi, Shrikant V.
    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).
    Sivakumar, G.
    International Advanced Research Centre for Powder Metallurgy & New Materials (ARCI), Hyderabad,India.
    New Generation Ceramic Coatings for High-Temperature Applications by Liquid Feedstock Plasma Spraying: Defense, Security, Aerospace and Energy Applications2020Ingår i: Handbook of Advanced Ceramics and Composites / [ed] Mahajan, Yashwant; Roy, Johnson, Cham: Springer, 2020, s. 1-42Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Plasma spraying with liquid feedstock offers an exciting opportunity to obtain coatings with characteristics that are vastly different from those produced using conventional spray-grade powders. The two extensively investigated variants of this technique are suspension plasma spraying (SPS), which utilizes a suspension of fine powders in an appropriate medium, and solution precursor plasma spraying (SPPS), which involves use of a suitable solution precursor that can form the desired particles in situ. The advent of axial injection plasma spray systems in recent times has also eliminated concerns regarding low deposition rates/efficiencies associated with liquid feedstock. The 10–100 μm size particles that constitute conventional spray powders lead to individual splats that are more than an order of magnitude larger compared to those resulting from the fine (approximately 100 nm–2 μm in size) particles already present in suspensions in SPS or formed in situ in SPPS. The distinct characteristics of the resulting coatings are directly attributable to the above very dissimilar splats (“building blocks” for coatings) responsible for their formation. This chapter discusses the salient features associated with SPS and SPPS processing, highlights their versatility for depositing a vast range of ceramic coatings with diverse functional attributes, and discusses their utility, particularly for high-temperature applications through some illustrative examples. A further extension of liquid feedstock plasma processing to enable use of hybrid powder-liquid combinations for plasma spraying is also discussed. This presents a novel approach to explore new material combinations, create various function-dependent coating architectures with multi-scale features, and enable convenient realization of layered, composite, and graded coatings as demonstrated through specific examples.

  • 23.
    Krishnamurthy, Kumar
    et al.
    SV College of Engineering, Department of Electrical and Electronics Engineering, Tirupati, India.
    Padmanaban, Sanjeevikumar
    Aalborg University, Department of Energy Technology, Esbjerg, Denmark.
    Blaabjerg, Frede
    Aalborg University, Center for Reliable Power Electronics (CORPE), Department of Energy Technology, Aalborg, Denmark.
    Neelakandan, Ramesh. Babu
    M.Kumarasamy College of Engineering, Karur, India.
    Ramanathan, Prabhu K.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Power Electronic Converter Configurations Integration with Hybrid Energy Sources: A Comprehensive Review for State-of the-Art in Research2020Ingår i: Electric power components and systems, ISSN 1532-5008, E-ISSN 1532-5016Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electricity demand is increasing day by day. On the other side, fossil fuels are depleting at a higher rate. The abundantly available renewable energy sources like solar, wind, and fuel cells are becoming popular sources of energy. But due to the intermittent availability of these renewable energy sources, two or more energy sources are integrated together. Power electronic converters are used for integrating different energy sources. Various power electronic converter (PEC) topologies have been proposed and analyzed in detail to control maximum power point, voltage, frequency, and harmonic distortions. Each of these configurations will differ in its topology and operating principle. The objective of this paper is to present a comprehensive review of various aspects of PEC configurations available for integration of renewable energy sources by systematization into three groups (AC shunt coupled, DC shunt coupled, and hybrid coupled systems). Emphasis is also given to coordination power control, maximum power point, and grid integration challenges related to the hybrid energy system. Furthermore, a general, system modeling of solar, wind, and grid integration is presented here to give an overall picture of a hybrid renewable energy system. ©2020 Taylor & Francis Group, LLC.

  • 24.
    Raza, Tahira
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Process Understanding and Weldability of Laser-Powder Bed Fusion Manufactured Alloy 7182020Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Den laserbaserade pulverbäddmetoden (L-PBF) är en av de vanligaste additiv tillverkningsmetod, där komponenter byggs upp genom att smälta metallpulver med hjälp av laser. Det finns ingen universell uppsättning av parametrarna som kan användas för alla olika material och geometrier. Forskningen som här utförts beträffande processparametrar visade att lasereffekten, skanningshastighet, exponeringstid för laser och dess avstånd mellan två laser punkter var väsentliga för att minska antalet bindfel i materialet. Gasporositet var dessvärre oundvikligt då det primärt härstammar från antingen pulverframställningen eller gasinneslutning under L-PBF processen.

    För att kunna utnyttja L-PBF-tekniken fullt ut som en kommersiell produktionsprocess kan sammanfogning av små L-PBF-delar för att bygga större eller mer komplexa komponenter, till exempel komponenter för jetmotorer, vara en lösning. Mikrostrukturen hos L-PBF tillverkad superlegering 718, som undersökts i detta projekt, har kristallkorn som mestadels är utsträckta i komponentens byggriktning. Kristallkornen i den tillverkade komponenten har en mycket fin cellulär till dendritisk struktur. Legeringens mikrostruktur innehåller dessutom utskiljningar som niobkarbid, titannitrid och den lågsmältande lavesfasen i de interdendritiska områdena samt längs korngränserna. Det genomfördes olika värmebehandlingar för att studera dess inverkan påvarmsprickor. Varm Isostatisk Pressning (HIP), upplösningsbehandling ochåldring utfördes på L-PBF-tillverkat material före svetsning för att jämföra medL-PBF-718-material utan värmebehandling samt även för att jämföra med 718 i plåtform. Resultaten visade att L-PBF-718 var känsligt för sprickbildning i HAZunder svetsning efter alla de typer av värmebehandlingar som undersöktes. Orsaken till varmsprickorna var relaterat till återuppsmältning av sekundära faser.

    L-PBF-718 som utsatts för HIP-behandling visade sig vara mer benägen försprickbildning och var dessutom mindre duktilt. Svetsriktningen i förhållande till riktningen för korntillväxt visade sig också ha en betydande inverkan på känsligheten för varmsprickor. Sprickor i HAZ observerades dessutom vara markant mindre i de prover som var svetsade parallellt med tillväxtriktningen äni prover där svetsningen utfördes vinkelrätt mot den.

    Ladda ner fulltext (pdf)
    fulltext
    Ladda ner fulltext (pdf)
    fulltext
  • 25.
    Jorge, Vinius Lemes
    et al.
    Federal University of Uberlandia, Uberlândia, MG, Brazil.
    Scotti, Fernando Matos
    Federal University of Uberlandia, Uberlândia, MG, Brazil.
    Reis, Ruham Pablo
    Federal University of Uberlandia, Uberlândia, MG, Brazil.
    Scotti, Américo
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    The effect of pulsed cold-wire feeding on the performanceof spray GMAW2020Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 107, s. 3485-3498Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The application of pulsed cold-wire (P-CW) feeding has been one of the new approaches for arc welding over the past years. Such technique applied to GTAW shows that it can influence the process performance. However, P-CW feeding in GMAW has not been explored yet. Thus, the current work aimed at introducing and evaluating the effects of P-CW on the performance of GMAW, particularly with the spray metal transfer. The P-CW pulsing frequency and the angle between the cold-wire and the plate were varied in bead-on-plate and V-groove weldments. The effects of the P-CW on the weld bead geometry and metallurgical texture were, then, examined through cross-sections. The metal transfer from the wire tip to the weld pool and the arc behavior during wire feeding were analyzed backed by high-speed imaging. A thermal camera was used to monitor the back of the plates to examine the heat behavior with both the P-CW and non-pulsed feeding conditions. On the one hand, the results revealed that, although the pulsation affects the arc and the electric signal behavior and the metal transfer, no sensitive influence could be noticed regarding the weld bead geometries. On the other hand, the pulsed cold-wire feeding interfered in the thermal profile outside the weld pool. For the highest frequency explored, regardless the feeding angle, less heat was transferred to the plate. The smaller heat input in these cases limited grain growth, reducing the coarse grain HAZ area and resulting in a more refined microstructure. Therefore, P-CW showed to interfere in the GMAW process performance.

  • 26.
    Ferreira Magalhães, Ana Catarina
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Thermoelectric Measurements for Temperature Control of Robotic Friction Stir Welding2020Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Friktionsomrörningssvetsning (FSW) genomgår en snabb industriell utveckling inom bland andra flyg-, marin-, järnvägs- och fordonssektorn, speciellt i aluminium. Aktuella industriella tillämpningar har hittills huvudsakligen varit enkla långa raka svetsar, men intresset för komponenter med högre geometrisk komplexitet ökar. Sådana komponenter utgör en utmanande uppgift på grund avvarierande inducerad termisk spridning längs med fogen, och särskilt på grund av behovet av lämplig utrustning, som kan följa en 3D-svetsbana. Detta gäller speciellt när verktyget monteras på en industrirobot, där höga processkrafter resulterar i böjning, vilka kan leda till svetsfel och sämre mekaniska egenskaper. Utgångspunkten i detta arbete är att temperaturen i verktygets kontakt med materialet har störst betydelse för fogkvaliteten.

    I det presenterade tillvägagångssättet styrs rotationshastigheten under svetsningen för att bibehålla önskad temperatur längs svetsen. En innovativ temperaturmätmetod baserad på termoelektrisk effekt mellan verktyg och arbetsstycke (TWT) erbjuder en skattning av temperaturen från hela gränssnittet mellan verktyg och arbetsstycke (TWT-data). Denna temperaturskattning används som den styrda variabeln. Det övergripande syftet med denna avhandling är att visa att styrning baserad på TWT-data är industriellt användbar för att bibehålla fogegenskaper vid fogning av geometriskt komplexa komponenter med hjälp av friktionsomröringssvetsning.

    TWT-data visar sig vara ett snabbt, repeterbart och genomförbart sätt att få en representativ realtidsskattning av fogens temperatur under hela processen. Som sådan är den lämplig för skattning av processtemperaturen och styrning av processen. TWT-data tillhandahåller information även under startskedet och identifierar när verktyget pressas mot arbetsstycket, och speciellt när verktygets skuldra får kontakt med arbetsstycket. Denna information ger en förbättrad startprocedur, vilket är viktigt speciellt vid robotisering, eftersom robotens vekhet påverkar verktygets z-position.

    Svetsning under temperaturreglering gav förbättrad fogprestanda, låg draghållfasthetsvariation längs fogen och ett reducerat antal misslyckade svetsar, och förväntas förenkla utvecklingen av en svetsprocedur, vilket möjliggör en minskning av tid och material.

    Konceptet validerades framgångsrikt genom att svetsa en komponent bestående av två olika fogar med en tvådimensionell svetsbana i en geometriskt komplexkomponent med hjälp av robotutrustning. Tillvägagångssättet för temperaturstyrning är inte begränsat till robotutrustning, utan också lämpligt för standard FSW-utrustning, vilket är av intresse för olika applikationer där kvalitet och tid är viktiga faktor.

    Ladda ner fulltext (pdf)
    fulltext
  • 27.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Welding metallurgy and weldability of superalloys2020Ingår i: Metals, ISSN 2075-4701, Vol. 10, nr 1, artikel-id 143Artikel i tidskrift (Refereegranskat)
    Ladda ner fulltext (pdf)
    fulltext
  • 28.
    Reddy, Damodhar
    et al.
    School of Electrical Engineering, Vellore Institute Technology, Vellore, 632014, India.
    Ramasamy, Sudha
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    A back propagation network based MPPT algorithm for grid-tied wind energy system with Vienna Rectifier2019Ingår i: International Journal of Renewable Energy Research, ISSN 1309-0127, Vol. 9, nr 2, s. 1097-1107Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a boost type Vienna Rectifier with a back propagation network algorithm for maximum power point tracking (MPPT) from the wind energy system. The preferred control algorithm deals with non-linear problems with improved conversance precision and reduced learning time. In this system, boost type Vienna Rectifier is employed as a machine side converter for single stage energy conversion of AC to DC with the enhanced output voltage and a grid side converter worked for DC to AC conversion. Vienna Rectifier facilitates power flow with high power density, continuous sinusoidal input current, improved power factor and offers low voltage stress across the switches. The proposed system is designed to meet the load power demand of 1kW Active power with the combined contribution of the wind and the main grid. The resulting analysis of the Vienna Rectifier with the aforementioned control algorithm is validated through Matlab-Simulink for variable wind speeds. © 2019, International Journal of Renewable Energy Research.

  • 29.
    Ganvir, Ashish
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Björklund, Stefan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Yao, Yiming
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, 41296, Sweden.
    Vadali, Srikanth V.S.S.
    University of Hyderabad, School of Engineering Sciences and Technology, Hyderabad, 500046, India.
    Klement, Uta
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, 41296, Sweden.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    A facile approach to deposit graphenaceous composite coatings by suspension plasma spraying2019Ingår i: Coatings, ISSN 2079-6412, Vol. 9, nr 3, artikel-id 171Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper demonstrates, for the first time ever, the deposition of graphenaceous composite coatings using an easy, yet robust, suspension plasma spraying (SPS) process. As a case study, a composite coating comprising 8 wt.% of yttria-stabilized-zirconia (8YSZ) and reinforced with graphene oxide (GO) was deposited on a steel substrate. The coatings were sprayed using an 8YSZ-GO mixed suspension with varied plasma spray parameters. Establishing the possibility of retaining the graphene in a ceramic matrix using SPS was of specific interest. Electron microscopy and Raman spectroscopy confirmed the presence of graphenaceous material distributed throughout the coating in the 8YSZ matrix. The experimental results discussed in this work confirm that SPS is an immensely attractive pathway to incorporate a graphenaceous material into virtually any matrix material and can potentially have major implications in enabling the deposition of large-area graphene-containing coatings for diverse functional applications. © 2019 by the authors.

    Ladda ner fulltext (pdf)
    fulltext
  • 30.
    Ferreira Magalhães, Ana Catarina
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Cederqvist, Lars
    SKB AB, Oskarshamn, Sweden.
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Håkansson, Emil
    Volvo Cars, Göteborg, Sweden.
    Ossiansson, Bruno
    Volvo Cars, Skövde, Sweden.
    Bolmsjö, Gunnar
    Linnaeus University, Växjö, Sweden.
    A Friction Stir Welding case study using Temperature Controlled Robotics with a HPDC Cylinder Block and dissimilar materials joining2019Ingår i: Journal of Manufacturing Processes, ISSN 1526-6125, Vol. 46, s. 177-184Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The automotive industry is going through a radical transformation from combustion engines to fully electric propulsion, aiming at improving key performance indicators related to efficiency, environmental sustainability and economic competitiveness. In this transition period, it is important to continue the innovation of combustion engines for e.g. plug-in hybrid vehicles. This led Volvo Cars to pursue radically new manufacturing processes such as Friction Stir Welding (FSW). The work presented in this paper is a case study whereby feasibility of using FSW to join a reinforcement element into the aluminium casted Cylinder Block was studied. The complex geometry of the joint required a flexible five-axis manipulator, i.e. an industrial robot, as well as advanced process control, i.e. temperature feedback control, in order to maintain a consistent weld quality throughout the whole component. The process was successfully demonstrated in a lab environment and offers a cost-efficient solution while maintaining the durability and higher efficiency. The outcome of this study shows the great potential of implementing the FSW process in combination with High Pressure Die Casted components, such a Cylinder Block. © 2019 The Society of Manufacturing Engineers

  • 31.
    Devotta, Ashwin Moris
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW). R&D Turning, Sandvik Coromant AB, Sandviken, 811 81, Sweden.
    Sivaprasad, Palla Venkata
    R&D, Sandvik Materials Technology AB, Sandviken, 811 81, Sweden.
    Beno, Tomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Eynian, Mahdi
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Hurtig, Kjell
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Magnevall, Martin
    R&D, Sandvik Coromant AB, 811 81 Sandviken, Sweden; Blekinge Institute of Technology, Department of Mechanical Engineering, SE-371 41 Karlskrona, Sweden .
    Lundblad, Mikael
    R&D, Sandvik Coromant AB, 811 81 Sandviken, Sweden.
    A modified Johnson-Cook model for ferritic-pearlitic steel in dynamic strain aging regime2019Ingår i: Metals, ISSN 2075-4701, Vol. 9, nr 5, artikel-id 528Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, the flow stress behavior of ferritic-pearlitic steel (C45E steel) is investigated through isothermal compression testing at different strain rates (1 s-1, 5 s-1, and 60 s-1) and temperatures ranging from 200 to 700 °C. The stress-strain curves obtained from experimental testing were post-processed to obtain true stress-true plastic strain curves. To fit the experimental data to well-known material models, Johnson-Cook (J-C) model was investigated and found to have a poor fit. Analysis of the flow stress as a function of temperature and strain rate showed that among other deformation mechanisms dynamic strain aging mechanism was active between the temperature range 200 and 400 °C for varying strain rates and J-C model is unable to capture this phenomenon. This lead to the need to modify the J-C model for the material under investigation. Therefore, the original J-C model parameters A, B and n are modified using the polynomial equation to capture its dependence on temperature and strain rate. The results show the ability of the modified J-C model to describe the flow behavior satisfactorily while dynamic strain aging was operative. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

  • 32.
    Valiente Bermejo, María Asunción
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Hurtig, Kjell
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Eyzop, Daniel
    Outokumpu Stainless AB, Avesta R&D Center, 774 41 Avesta, Sweden.
    Karlsson, Leif
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    A New Approach to the Study of Multi-Pass Welds–Microstructure and Properties of Welded 20-mm-Thick Superduplex Stainless Steel2019Ingår i: Applied Sciences, E-ISSN 2076-3417, Vol. 9, nr 6, artikel-id 1050Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Type 2507 superduplex stainless steel 20 mm in thickness was multi-pass-welded with Gas Metal Arc Welding (GMAW) and Flux-Cored Arc Welding (FCAW) processes. Recommended and higher arc energies and inter-pass temperatures were used. Thermal cycles were monitored using a recently developed procedure involving the successive instrumentation of the multi-pass welds, pass by pass, by addition of thermocouples in each weld pass. The repeatability of temperature measurements and survival rate of more than 90% of thermocouples confirmed the reliability of the procedure. Reheating by subsequent passes caused a progressive increase in the austenite content of the weld metal. The as-deposited GMAW passes with higher-than-recommended arc energy showed the lowest presence of nitrides. Therefore, the cooling rate&mdash;and not the time exposed at the critical temperature range&mdash;seems to be the key factor for nitride formation. The welding sequence layout also plays an important role in the distribution of secondary phases. A larger amount and concentration of secondary austenite and &sigma;-phase was found for a larger number of subsequent passes in the immediate vicinity of a specific weld pass. The impact toughness exceeded requirements for all welds. Differences in absorbed energies were related to the amount of micro-inclusions found with the FCAW weld showing the lowest absorbed energies and highest amount of micro-inclusions. Pitting corrosion preferentially initiated in locations with secondary austenite and &sigma;-phase. However, in the absence of these secondary phases, the HAZ containing nitrides was the weakest location where pitting initiated. The results of this work have implications on practical welding for superduplex stainless steels: the current recommendations on maximum arc energy should be revised for large thickness weldments, and the importance of the welding sequence layout on the formation of secondary phases should be considered.

    Ladda ner fulltext (pdf)
    fulltext
  • 33.
    Eriksson, Kristina M.
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Chirumalla, Koteshwar
    Ericsson, Mikael
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    A novel blended learning course developed jointly between three universities to address competence development of professionals in digitalized manufacturing2019Ingår i: VILÄR 5-6 december 2019, University West, Trollhättan: Abstracts / [ed] Kristina Johansson, Trollhättan: University West , 2019, s. 6-7Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    New competences and knowledge needs arises as manufacturing industry evolves and becomes increasingly digitalized. Facing this transformation, one of the challenges is the continuous and growing need for novel initiatives for competence development.The case portrayed here stems from a Swedish cross-university project aiming to jointly develop and offer courses for competence development of professionals in the manufacturing and IT sectors. The ambition is to increase the impact of the universities' respective efforts of meeting industry competence needs, where the continuous digital transformation entails that employees must develop or even change their qualifications.

    The case outlined focus co-production of a joint course package, at master level, between three universities and their respective company networks. Participating universities have long traditions in working closely with companies in research and education, where approaches for co-production have evolved over time. We make use of our joint understanding of the manufacturing industry's specific competence needs and our experiences of sustainable course formats for participants working full time.The joint course covers aspects of a manufacturing company on three levels: plant level i.e. material and production flows, cell level e.g. robotic simulation and visualisation, and system level i.e. data acquisition and monitoring through sensors. Each university is developing a course module of 2.5 ECTS, addressing a level respectively of their specialist competence. Participants are to complete assignments for each course module, i.e. for all three manufacturing levels, where the previous assignment provides an input to the next level, enabling the participants to encompass a holistic view of a manufacturing system. Participants need to combine study and work and at the same time they wish to extend their network, hence we are adopting a blended learning approach, where virtual labs and web conferences are mixed with physical meetings.A variety of challenges arise when designing such novel approaches: combining company networks, course design including online learning, planning of physical course meetings,

    joint promotion, common admission and validation process, financial models and more. However, engaging in partnerships with industry for knowledge transformation and development has the potential to become rewarding for all parties.

  • 34.
    Asala, Gbenga
    et al.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Ojo, Olanrewaju A.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    A study of the dynamic impact behaviour of IN 718 and ATI 718Plus® superalloys2019Ingår i: Philosophical Magazine, ISSN 1478-6435, E-ISSN 1478-6443, Vol. 99, nr 4, s. 419-437Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dynamic impact response of IN 718 and ATI 718Plus®, in both the solution heat treated and age-hardened conditions, were investigated at different deformation temperatures and strain rates using a direct impact Hopkinson pressure bar. Analyses of the results provide a vital but previously not reported information that the ATI 718Plus® offers a higher resistance to damage during high strain rate ballistic impact deformation compared to the most widely used Iron-nickel based superalloy, Inconel 718. ATI 718Plus® showed higher strain hardening and strain rate sensitivity, in both heat treatment conditions, than IN 718. The difference in the deformation behaviour of both alloys, in the annealed condition, is attributable to the compositional modification in ATI 718Plus® which has been reported to lower its stacking fault energy and increases the tendency for deformation twinning. However, in the age-hardened condition, the difference is believed to be related to the disparity in the operative strengthening mechanism, of the precipitates present in both alloys. Furthermore, a higher susceptibility to strain location and the formation of adiabatic shear band, in aged IN 718, is attributable to the stronger temperature-softening characteristics observed in the alloy and to the limited strain hardening tendency under dynamic impact loading. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.

  • 35.
    Nilsen, Morgan
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Sikström, Fredrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Christiansson, Anna-Karin
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    A study on change point detection methods applied to beam offset detection in laser welding2019Ingår i: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 36, s. 72-79Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents an experimental study where a photodiode integrated into a laser beam welding tool is used to monitor laser beam spot deviations fromthe joint, the beam offset. The photodiode system is cost effective and typically easy to implement in an industrial system. The selected photodiode is a silicondetector sensitive in the spectral range between 340-600nm which corresponds to the spectral emissions from the plasma plume. The welding application is closed-square-butt joint welding where a laser beam offset can cause lack of fusion in the resulting weld. The photodiode signal has been evaluated by two different change point detection methods, one off-line and one on-line method, with respect to their detection performance. Off-line methods can be used to guide post weld inspection and on-line methods have the potential to enable on-line adaptive control or the possibility to stop the process for repair. The performance of the monitoring system and the change point detection methods have been evaluated from data obtained during laser beam welding experiments conducted on plates of stainless steel. The results clearly indicates the possibility to detect beam offsets by photodiode monitoring.

  • 36.
    Nilsen, Morgan
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Sikström, Fredrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Christiansson, Anna-Karin
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Adaptive control of the filler wire rate during laser beam welding of squared butt joints with varying gap width2019Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 102, nr 9-12, s. 3667-3676Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Adding filler wire control to autogenous laser beam welding of squared butt joints offers a means to widen up the tight fit-up tolerances associated with this process. When the gap width varies, the filler wire rate should be controlled to assure a constant geometry of the resulting weld seam. A dual mode sensing system is proposed to estimate the joint gap width and thereby control the filler wire rate. A vision camera integrated into the welding tool together with external LED illumination and a laser line projection enables two sensing modes, one surface feature extraction mode and one laser triangulation-based mode. Data from the both modes are fused in a Kalman filter, and comparisons show that the fusing of the data gives more robust estimation than estimates from each single mode. A feed-forward control system adaptively adjusts the filler wire rate based on the estimations ofthe joint gap width in front of the keyhole. The focus is on keeping the data processing simple and affordable, and the real-time performance of the sensor and control system has been evaluated by welding experiments. It is shown that the proposed system can be used for on-line control of the filler wire rate to achieve a constant weld geometry during varying joint gap widths

    Ladda ner fulltext (pdf)
    fulltext
  • 37.
    Sadeghi, 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).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Advances in Corrosion-Resistant Thermal Spray Coatings for Renewable Energy Power Plants. Part I: Effect of Composition and Microstructure2019Ingår i: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 28, nr 8, s. 1749-1788Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Power generation from renewable resources has attracted increasing attention in recent years owing to the global implementation of clean energy policies. However, such power plants suffer from severe high-temperature corrosion of critical components such as water walls and superheater tubes. The corrosion is mainly triggered by aggressive gases like HCl, H2O, etc., often in combination with alkali and metal chlorides that are produced during fuel combustion. Employment of a dense defect-free adherent coating through thermal spray techniques is a promising approach to improving the performances of components as well as their lifetimes and, thus, significantly increasing the thermal/electrical efficiency of power plants. Notwithstanding the already widespread deployment of thermal spray coatings, a few intrinsic limitations, including the presence of pores and relatively weak intersplat bonding that lead to increased corrosion susceptibility, have restricted the benefits that can be derived from these coatings. Nonetheless, the field of thermal spraying has been continuously evolving, and concomitant advances have led to progressive improvements in coating quality; hence, a periodic critical assessment of our understanding of the efficacy of coatings in mitigating corrosion damage can be highly educative. The present paper seeks to comprehensively document the current state of the art, elaborating on the recent progress in thermal spray coatings for high-temperature corrosion applications, including the alloying effects, and the role of microstructural characteristics for understanding the behavior of corrosion-resistant coatings. In particular, this review comprises a substantive discussion on high-temperature corrosion mechanisms, novel coating compositions, and a succinct comparison of the corrosion-resistant coatings produced by diverse thermal spray techniques.

    Ladda ner fulltext (pdf)
    fulltext
  • 38.
    Sadeghi, 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).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Advances in Corrosion-Resistant Thermal Spray Coatings for Renewable Energy Power Plants: Part II - Effect of Environment and Outlook2019Ingår i: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 28, nr 8, s. 1789-1850Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-temperature corrosion of critical components such as water walls and superheater tubes in biomass/waste-fired boilers is a major challenge. A dense and defect-free thermal spray coating has been shown to be promising to achieve a high electrical/thermal efficiency in power plants. The field of thermal spraying and quality of coatings have been progressively evolving; therefore, a critical assessment of our understanding of the efficacy of coatings in increasingly aggressive operating environments of the power plants can be highly educative. The effects of composition and microstructure on high-temperature corrosion behavior of the coatings were discussed in the first part of the review. The present paper that is the second part of the review covers the emerging research field of performance assessment of thermal spray coatings in harsh corrosion-prone environments and provides a comprehensive overview of the underlying high-temperature corrosion mechanisms that lead to the damage of exposed coatings. The application of contemporary analytical methods for better understanding of the behavior of corrosion-resistant coatings is also discussed. A discussion based on an exhaustive review of the literature provides an unbiased commentary on the advanced accomplishments and some outstanding issues in the field that warrant further research. An assessment of the current status of the field, the gaps in the scientific understanding, and the research needs for the expansion of thermal spray coatings for high-temperature corrosion applications is also provided. © 2019, The Author(s).

    Ladda ner fulltext (pdf)
    fulltext
  • 39.
    Svenman, Edvard
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    An inductive gap measurement method for square butt joints2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    A recent method in aero engine production is to fabricate components from smaller pieces, rather than machining them from large castings. This has made laser beam welding popular, offering high precision with low heat input and distortion, but also high productivity. At the same time, the demand for automation of production has increased, to ensure high quality and consistent results. In turn, the need for sensors to monitor and control the laser welding process is increasing. In laser beam welding without filler material, the gap between the parts to be joined must be narrow. Optical sensors are often used to measure the gap, but with precise machining, it may become so narrow that it is difficult to detect, with the risk of welding in the wrong position. This thesis proposes the use of an inductive sensor with coils on either side of the gap. Inducing currents into the metal, such a sensor can detect even gaps that are not visible. The new feature of the proposal is based on using the complex response of each coil separately to measure the distance and height on both sides of the gap, rather than an imbalance from the absolute voltage of each coil related to gap position. This extra information allows measurement of gap width and alignment as well as position in a working range of about 1 mm around the gap, and decreases the influence from variation in gap alignment to the position measurement. The sensor needs to be calibrated with a certain gap width and height alignment. In real use, these will vary, causing the sensor to be less accurate. Using initial estimates of the gap parameters from the basic sensor, a model ofthe response can be used to estimate the measurement error of each coil, whichin turn can be used for compensation to improve the measurement of the gap properties. The properties of the new method have been examined experimentally, using aprecise traverse mechanism to record single coil responses in a working range around a variable dimension gap, and then using these responses to simulate atwo coil probe. In most cases errors in the measurement of weld gap position and dimensions are within 0.1 mm. Different coil orientations were studied using numerical simulation, and validated in experiments using a two coil probe. The influence of scratches, chamfers and variation in plate thickness was investigated at different frequencies.

    Ladda ner fulltext (pdf)
    Avhandling
    Ladda ner fulltext (pdf)
    Erratablad
  • 40.
    Asala, Gbenga
    et al.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, R3T 5V6, Canada.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Ojo, Olanrewaj A.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, R3T 5V6, Canada.
    Analysis and constitutive modelling of high strain rate deformation behaviour of wire-arc additive-manufactured ATI 718Plus superalloy2019Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 103, nr 1-4, s. 1419-1431Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A fundamental prerequisite for obtaining realistic finite element simulation of machining processes, which has become a key machinability assessment for metals and alloys, is the establishment of a reliable material model. To obtain the constitutive model for wire-arc additive-manufactured ATI 718Plus, Hopkinson pressure bar is used to characterise the flow stress of the alloy over a wide range of temperatures and strain rates. Experiment results show that the deformation behaviours of as-deposited ATI 718Plus superalloy are influenced by the applied strain rate, test temperature and strain. Post-deformation microstructures show localised deformation within the deposit, which is attributable to the heterogeneous distribution of the strengthening precipitates in as-deposited ATI 718Plus. Furthermore, cracks are observed to be preferentially initiated at the brittle eutectic solidification constituents within the localised band. Constitutive models, based on the strain-compensated Arrhenius-type model and the modified Johnson-Cook model, are developed for the deposit based on experimental data. Standard statistical parameters, correlation coefficient (R), root-mean-square error (RMSE) and average absolute relative error (AARE) are used to assess the reliability of the models. The results show that the modified Johnson-Cook model has better reliability in predicting the dynamic flow stress of wire-arc-deposited ATI 718Plus superalloy. © 2019, Springer-Verlag London Ltd., part of Springer Nature.

  • 41.
    Ramasamy, Sudha
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Zhang, Xiaoxiao
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Bennulf, Mattias
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Danielsson, Fredrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Automated Path Planning for Plug Produce in a Cutting-tool Changing Application2019Ingår i: 24th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), 2019, s. 356-362, artikel-id 8869398Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, a path planning algorithm is designed and tested with a real robot for a Plug & Produce demonstrator. The demonstrator is divided into modules that can be connected and removed. Modules are used for various processes like tool change and storage. This paper focuses on the process of cutting-tool change for the production industry. The Plug & Produce demonstrator uses a multi-agent system where parts and resources are agents. A part agent, e.g., a cutting-tool, can request a robot to perform skills like transportation. This requires the robot to be autonomous. The aim of this paper is to automate the path planning for industrial robotics in a Plug & Produce system. This is done by implementing a sampling based RRT algorithm combined with a collision detection function in RobotStudio. With various real time scenarios, the path planning execution time is observed and presented in the paper.

  • 42.
    Hameed, Pearlin
    et al.
    Centre for Biomaterials, Cellular & Molecular Theranostics (CBCMT), Vellore Institute of Technology, Vellore, 632014, India.
    Gopal, Vasanth
    Centre for Biomaterials, Cellular & Molecular Theranostics (CBCMT), Vellore Institute of Technology, Vellore, 632014, India; Department of Physics, School of Advanced Sciences, Vellore Institute of Technology, Vellore, 632014, India.
    Björklund, Stefan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Ganvir, Ashish
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sen, Dwaipayan
    Centre for Biomaterials, Cellular & Molecular Theranostics (CBCMT), Vellore Institute of Technology, Vellore, 632014, India.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Manivasagam, Geetha
    Centre for Biomaterials, Cellular & Molecular Theranostics (CBCMT), Vellore Institute of Technology, Vellore, 632014, India.
    Axial Suspension Plasma Spraying: An ultimate technique to tailor Ti6Al4V surface with HAp for orthopaedic applications2019Ingår i: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 173, s. 806-815Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dissolution of atmospheric plasma sprayed (APS) hydroxyapatite (HAp) coatings on Ti-6Al-4 V medical implants have always been a challenge to overcome in the field of biomedical industry. In the present work, an attempt has been made to develop a HAp coating using a novel thermal spray process called axial suspension plasma spraying (SPS), which leads to thin adherent coatings. Two HAp coatings fabricated by APS (P1 and P2) and four SPS HAp coatings (S1, S2, S3 and S4) produced with varying spraying parameters were characterized in terms of (1) microstructure, porosity, hardness, adhesion strength, contact angle and phase purity; (2) corrosion resistance in 10% Fetal bovine serum (FBS); (3) in-vitro cell adherence and cell viability using human umbilical cord blood-derived mesenchymal stem cells (hMSCs). Amongst different APS and SPS coatings, P1 and S3 exhibited superior properties. S3 coating developed using SPS exhibited 1.3 times higher adhesion strength when compared to APS coating (P1) and 9.5 times higher corrosion resistance than P1. In addition, both S3 and P1 exhibited comparatively higher biocompatibility as evidenced by the presence of more than 92% viable hMSCs. © 2018 Elsevier B.V.

  • 43.
    Sikström, Fredrik
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Nilsen, Morgan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Beam offset detection in laser stake welding of tee joints based on photodetector sensing2019Ingår i: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 36, s. 64-71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents an experimental study where a photodetector is used in a laser beam welding tool to monitor beam deviations (beam offsets) in stake welding of tee joints. The aim is to obtain an early detection of deviations from the joint centerline in this type of welding where the joint is not visible from the top side. The photodetector used is a GaP diode sensitive in the spectral range 150-550 nm corresponding to the spectral emissions form the plasma plume during keyhole welding. The photodetector signal has been evaluated by change point detection methods with respect to their detection performance. Both an off-line and an on-line method have been evaluated. The off-line method can be used to guide post weld inspection and the on-line method has the potential to enable on-line adaptive position control and/or the possibility to stop the process for repair. The results shows that the proposed method can be used as a go/no go system and to guide post weld inspection.

  • 44.
    Gupta, Siddhartha
    et al.
    VIT Vellore,School Of Electrical Engineering (SELECT),Vellore,India.
    Sinha, Neha
    VIT Vellore,School Of Electrical Engineering (SELECT),Vellore,India.
    Ramasamy, Sudha
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Babu, Challa
    VIT Vellore,School Of Electrical Engineering (SELECT),Vellore,India.
    Breast Cancer Detection Using Image Processing Techniques2019Ingår i: 2019 Innovations in Power and Advanced Computing Technologies (i-PACT), Institute of Electrical and Electronics Engineers Inc. , 2019, Vol. 1Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cancer is the uncontrolled multiplication of group of cells in a particular location of the body and is the second largest disease leading to the death of women in the world. The disease can be cured if it is detected in early stages. A lot of research has been done to find out the tumor correctly but a 100% accurate method has not been found. Research on breast cancer detection using digital image processing is not new but many new approaches in this field is being considered to accurately predict the tumor region. The present approach is to detect the tumor region visually as well as to figure out in which region the tumor is mostly concentrated. This work majorly focuses on finding out the best algorithm/s to detect the tumor present in the breast. In the proposed work, a variety of algorithms has been applied but the best one suited for cancer detection is the combination of K Means, Closing, Dilation and Canny Edge Detection algorithm. © 2019 IEEE.

  • 45.
    Johansson, Pierre Eric Christian
    et al.
    Volvo Group Trucks Operations.
    Malmsköld, Lennart
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Fast-Berglund, Åsa
    Chalmers University of Technology, Göteborg, Sweden.
    Moestam, Lena
    Volvo, Gothenburg, Sweden.
    Challenges of handling assembly information in global manufacturing companies2019Ingår i: Journal of Manufacturing Technology Management, ISSN 1741-038X, E-ISSN 1758-7786Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose

    The purpose of this paper is to describe challenges the manufacturing industry is currently facing when developing future assembly information systems. More specific, this paper focuses on the handling of assembly information from manufacturing engineering to the shop floor operators.

    Design/methodology/approach

    Multiple case studies have been conducted within one case company between 2014 and 2017. To broaden the perspective, interviews with additionally 17 large and global manufacturing companies and 3 industry experts have been held. Semi-structured interviews have been the main data collection method alongside observations and web questionnaires.

    Findings

    Six focus areas have been defined which address important challenges in the manufacturing industry. For manual assembly intense manufacturing company, challenges such as IT challenges, process challenges, assembly process disturbances, information availability, technology and process control, and assembly work instructions have been identified and hinder implementation of Industry 4.0 (I4.0).

    Originality/value

    This longitudinal study provides a current state analysis of the challenges the manufacturing industry is facing when handling assembly information. Despite the vast amount of initiatives within I4.0 and digitalization, this paper argues that the manufacturing industry needs to address the six defined focus areas to become more flexible and prepared for the transition toward a digitalized manufacturing industry.

  • 46.
    Sadeghi, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Chlorine-induced high-temperature corrosion and erosion-corrosion of HVAF and HVOF-sprayed amorphous Fe-based coatings2019Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 371, nr S1, s. 20-35Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chlorine-induced high-temperature corrosion and erosion-corrosion behavior of amorphous Fe-based coatings sprayed by high velocity air-fuel (HVAF) and high velocity oxy-fuel (HVOF) techniques were investigated. The coated specimens were first exposed to isothermal high-temperature corrosion at 600 °C in ambient air with and without KCl. The exposed specimens were then subjected to alumina erodent. The as-sprayed HVAF coating showed a more compact and uniform microstructure with a higher hardness leading to higher corrosion and erosion-corrosion resistance. After erosion, all the coatings similarly exhibited a combined brittle/ductile damage to surface oxide scale that previously formed in the corrosive environment. The corrosion and erosion-corrosion behavior of the coatings primarily relied on the uniformity of coatings’ microstructure and distribution of alloying elements to form the protective oxide scale in the corrosive environment, which can resist against erodent in the erosive media. © 2019 Elsevier B.V.

  • 47.
    Aranke, Omkar
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Algenaid, Wael
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Awe, Samuel
    R and D Department, Automotive Components Floby AB, Floby, 52151, Sweden.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Coatings for automotive gray cast iron brake discs: A review2019Ingår i: Coatings, ISSN 2079-6412, Vol. 9, nr 9, artikel-id 552Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gray cast iron (GCI) is a popular automotive brake disc material by virtue of its high melting point as well as excellent heat storage and damping capability. GCI is also attractive because of its good castability and machinability, combined with its cost-effectiveness. Although several lightweight alloys have been explored as alternatives in an attempt to achieve weight reduction, their widespread use has been limited by low melting point and high inherent costs. Therefore, GCI is still the preferred material for brake discs due to its robust performance. However, poor corrosion resistance and excessive wear of brake disc material during service continue to be areas of concern, with the latter leading to brake emissions in the form of dust and particulate matter that have adverse effects on human health. With the exhaust emission norms becoming increasingly stringent, it is important to address the problem of brake disc wear without compromising the braking performance of the material. Surface treatment of GCI brake discs in the form of a suitable coating represents a promising solution to this problem. This paper reviews the different coating technologies and materials that have been traditionally used and examines the prospects of some emergent thermal spray technologies, along with the industrial implications of adopting them for brake disc applications. © 2019 by the authors.

    Ladda ner fulltext (pdf)
    fulltext
  • 48.
    Reddy, Damodhar
    et al.
    HITAM, Department of Electrical and Electronics Engineering, Hyderabad, India.
    Ramasamy, Sudha
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Comparative Analysis of P & O and RBFN MPPT Controller Based Three Level SEPIC Topology for 1.2kW Solar PV System2019Ingår i: Gazi University Journal of Science, E-ISSN 2147-1762, Vol. 32, nr 3, s. 853-869Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    This paper accords an intelligent controller based 3-level SEPIC configuration for energy transformation in the solar PV system. An artificial intelligence based radial basis function network is engaged as a control algorithm for the maximum power extraction and the converter control can be done based on the duty cycle generated by the controller. In this system, a SEPIC topology is used for high voltage gain with reduced switching losses. In this paper, an RBFN controller based 3-level SEPIC topology is designed for 1.2kW solar PV system over the traditional P & O (Perturb & Observe) control method and the comparative result analysis is done though the simulation output for the corresponding input parameters.

  • 49.
    dos Santos Paes, Luiz Eduardo
    et al.
    Federal University of Santa Catarina, Department of Mechanical Engineering, Laboratory of Precision Engineering, Laser Division (LMP-Laser), Florianópolis, Brazil.
    Pereira, Milton
    Federal University of Santa Catarina, Department of Mechanical Engineering, Laboratory of Precision Engineering, Laser Division (LMP-Laser), Florianópolis, Brazil.
    Weingaertner, Walter Lindolfo
    Federal University of Santa Catarina, Department of Mechanical Engineering, Laboratory of Precision Engineering, Laser Division (LMP-Laser), Florianópolis, Brazil.
    Scotti, Americo
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV). Federal University of Uberlandia, Center for Research and Development of Welding Processes (Laprosolda), Uberlândia Brazil.
    Souza, Tiago
    Federal University of Santa Catarina, Department of Mechanical Engineering, Laboratory of Precision Engineering, Laser Division (LMP-Laser), Florianópolis, Brazil.
    Comparison of methods to correlate input parameters with depth of penetration in LASER welding2019Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 101, nr 5-8, s. 1157-1169Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the industrial relevance of LASER welding, determination of sustainable parameterization is still a challenge. Trial and error, or even not totally justified methodologies, are frequently applied on LASER welding parametrization. This approach potentially leads to a decrease of the process tolerance and, consequently, increasing the likelihood of imperfections, which means extra operational time and raising of the final cost. The present paper addresses a comparative discussion about five factors experimentally determined and frequently used to predict depth of penetration in LASER welding. The experiments were performed with a 10-kW fiber LASER. In a first batch, power was varied while welding speed was fixed at 1 m/min. In a second batch, welding speed was varied and power was kept at 10 kW. The first demonstrated concern on using these popular factors is the definition and quantification of LASER energy. For evidencing this aspect, two samples were processed with the same welding energy of 120 kJ/m, yet resulting in completely different penetrations. Eventually, an empirical model based on power as a factor allowed a more reliable prediction of the depth of penetration.

  • 50.
    Valiente Bermejo, María Asunción
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Wessman, Sten
    Swerim AB, Kista, Sweden.
    Computational thermodynamics in ferrite content prediction of austenitic stainless steel weldments2019Ingår i: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, nr 3, s. 627-635Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, four computational approaches using Thermo-Calc and DICTRA have been used to calculate the ferrite content of a set of austenitic stainless steel welds with different solidification modes and ferrite contents. To evaluate the computational approaches, the calculations were compared to the experimental results. It was found that for each solidification mode, there is one computational approach that predicts ferrite with better accuracy. For ferritic-austenitic alloys, the best accuracy is obtained when considering the peritectic model, with deviations of 1.2–1.4% ferrite. In the case of austenitic-ferritic alloys, the solidification analysed through the eutectic approach showed an accuracy of 0.6–1.6% ferrite, whilst in alloys with fully ferritic solidification, starting calculations, not from the liquid state but from fully ferritic below solidus, was the best approach, showing 2.3% ferrite deviation from the experimental measurements. Computational thermodynamics has proved to be a promising tool to explore simulation and calculation of ferrite content phase fractions in welding. However, further investigation is still needed to correlate the real microstructural features with the computational parameter “cell size”. The feasibility and accuracy of computational thermodynamics when predicting ferrite in low-heat-input welding processes such as laser welding is also another aspect for additional investigation.

    Ladda ner fulltext (pdf)
    fulltext
1234567 1 - 50 av 867
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf