oru.sePublikasjoner
Endre søk
Begrens søket
123 1 - 50 of 117
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Arapan, S.
    et al.
    IT4Innovations, VSB-Technical University of Ostrava, Ostrava-Poruba, Czech Republic; ICCRAM, International Research Center in Critical Raw Materials and Advanced Industrial Technologies, University of Burgos, Burgos, Spain.
    Nieves, P.
    ICCRAM, International Research Center in Critical Raw Materials and Advanced Industrial Technologies, University of Burgos, Burgos, Spain.
    Cuesta-Lopez, S.
    ICCRAM, International Research Center in Critical Raw Materials and Advanced Industrial Technologies, University of Burgos, Burgos, Spain; ICAMCyL, International Center for Advanced Materials and Raw Materials of Castilla y Léon, Léon, Spain.
    Gusenbauer, M.
    Department for Integrated Sensor Systems, Danube University Krems, Wiener Neustadt, Austria.
    Oezelt, H.
    Department for Integrated Sensor Systems, Danube University Krems, Wiener Neustadt, Austria.
    Schrefl, T.
    Department for Integrated Sensor Systems, Danube University Krems, Wiener Neustadt, Austria.
    Delczeg-Czirjak, E. K.
    Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Uppsala, Sweden.
    Herper, H. C.
    Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Uppsala, Sweden.
    Eriksson, Olle
    Örebro universitet, Institutionen för naturvetenskap och teknik. Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Uppsala, Sweden.
    Influence of antiphase boundary of the MnAl tau-phase on the energy product2019Inngår i: Physical Review Materials, ISSN 2475-9953, Vol. 3, nr 6, artikkel-id 064412Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we use a multiscale approach to describe a realistic model of a permanent magnet based on MnAl tau-phase and elucidate how the antiphase boundary defects present in this material affect the energy product. We show how the extrinsic properties of a microstructure depend on the intrinsic properties of a structure with defects by performing micromagnetic simulations. For an accurate estimation of the energy product of a realistic permanent magnet based on the MnAl tau-phase with antiphase boundaries, we quantify exchange interaction strength across the antiphase boundary defect with a simple approach derived from first-principles calculations. These two types of calculations, performed at different scales, are linked via atomistic spin-dynamics simulations.

  • 2.
    Asnafi, Nader
    Sapa Technology, Finspång (and Vetlanda), Sweden.
    Analytical modelling of the forces and pressures required in hydropiercing2000Rapport (Annet vitenskapelig)
  • 3.
    Asnafi, Nader
    Sapa Technology, Finspång (and Vetlanda), Sweden .
    Automotive Tubular Hydroforming: Fundmentals and Industrial Practice2000Konferansepaper (Annet vitenskapelig)
  • 4.
    Asnafi, Nader
    Luleå University of Technology, Luleå, Sweden .
    Formbarhet under dragpressning, sträckpressning och bockning samt egenskaper efter formning av aluminiumplåt1988Rapport (Annet vitenskapelig)
  • 5.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Forming of Aluminium2002Konferansepaper (Annet vitenskapelig)
  • 6.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Hydroformability of Extra High Strength Steels in Structural Tubular Applications: an Analysis based on Literature Survey1997Rapport (Annet vitenskapelig)
  • 7.
    Asnafi, Nader
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Innovative Lead Time and Cost Efficient Tools and Dies for Lightweight Autobody Components2016Konferansepaper (Annet vitenskapelig)
  • 8.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Manufacturing the car body of tomorrow2002Konferansepaper (Annet vitenskapelig)
  • 9.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Nya material och processer vid framtagning av lättviktskarosser2004Konferansepaper (Annet vitenskapelig)
  • 10.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden .
    On Prediction of the Yield Strength of Pressed Panels by Using the Tensile Behaviour of the Virgin Material1992Konferansepaper (Annet vitenskapelig)
  • 11.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    On Springback of Double-Curved Autobody Panels, Part I: Theoretical Treatment1996Rapport (Annet vitenskapelig)
  • 12.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    On Springback of Double-Curved Autobody Panels, Part II: Experimental Analysis1996Rapport (Annet vitenskapelig)
  • 13.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden .
    On strength, stiffness and dent resistance of car body panels1995Inngår i: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 49, nr 1-2, s. 13-31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There are cases in which practitioners wish to be able to predict the properties of a panel, should they replace one material by another. In this study, the yield strength, stiffness and dent resistance of double-curvature car body panels are treated both theoretically and experimentally. The results of the investigation show that the above-mentioned properties of a pressed panel can be predicted provided that the magnitude of the principal surface strains and the magnitude of the panel radii at the panel centre are known.

  • 14.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    On Strength, Stiffness and Dent Resistance of Car Body Panels1993Rapport (Annet vitenskapelig)
  • 15.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    On Strength, Stiffness and Dent Resistance of Car Body Panels1993Konferansepaper (Annet vitenskapelig)
  • 16.
    Asnafi, Nader
    Gränges Technology, Finspång, Sweden.
    On stretch and shrink flanging of sheet aluminium by fluid forming1999Inngår i: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 96, nr 1-3, s. 198-214Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this investigation, vertical stretch and shrink flanging of sheet aluminium by fluid forming are studied experimentally and theoretically. The theoretical part comprises both analytical modelling and finite-element simulations.

    The fracture limit in stretch flanging is determined by the plastic strain ratio, the strain hardening exponent, and the uniform strain. The greater the magnitude of these parameters, the greater will be the fracture limit.

    The maximum applied pressure determines the ’wrinkling’ limit in shrink flanging by fluid forming. The greater is this pressure, the greater ’wrinkling’ limit. This limit is certainly several times greater in magnitude than that in shrink flanging by conventional tools (a rigid punch and die).

  • 17.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    On Stretch and Shrink Flanging of Sheet Aluminium by Fluid Forming1996Rapport (Annet vitenskapelig)
  • 18.
    Asnafi, Nader
    Industrial Development Center/Volvo Cars Body Components, Olofström, Sweden .
    On Stretch and Shrink Flanging of Sheet Aluminium by Fluid Forming1998Inngår i: Proceedings, working groups meeting - IDDRG, International Deep Drawing Research Group: Genval, Benelux, June 15 - 16, 1998, 1998Konferansepaper (Annet vitenskapelig)
  • 19.
    Asnafi, Nader
    Industrial Development Centre, Olofström, Sweden.
    On tool stresses in cold heading of fasteners1999Inngår i: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 6, nr 5, s. 321-335Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this investigation, attention was focused on the tool stresses that emerge during manufacturing of fasteners. These stresses were studied both experimentally and theoretically. The theoretical part comprised finite-element simulation. This simulation showed that the zone at the die insert profile radius is so heavily loaded that plastic deformation is initiated in this region. In the experimental part, the emerging strains were measured in the region close to the interface between the die insert and the stress ring. The correspondence is good between the theoretical and experimental strains in this region. In spite of this and although 20 fasteners were cold-forged, the die insert did not fracture. Forming at production facilities showed that the die insert cracked after 9080 parts were produced. The results obtained in this investigation and the test conducted at production facilities indicate that high cycle fatigue, and not monotomic rupture, is the main cause of tool fracture in practice.

  • 20.
    Asnafi, Nader
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Proceedings of the 2nd International Conference on Material Engineering and Advanced Manufacturing Technology (MEAMT 2018)2018Konferanseproceedings (Fagfellevurdert)
  • 21.
    Asnafi, Nader
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Proceedings of the International Conference on Mechanical, Electric and Industrial Engineering (MEIE2018)2018Konferanseproceedings (Fagfellevurdert)
  • 22.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Springback & Fracture in V-Die Bending: A Literature Survey of Analytical Models1996Rapport (Annet vitenskapelig)
  • 23.
    Asnafi, Nader
    Gränges Technology, Finspång, Sweden.
    Springback and fracture in v-die air bending of thick stainless steel sheets2000Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 21, nr 3, s. 217-236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this investigation, the attention is focused on the springback and fracture of thick stainless steel sheets. Nine different stainless grades and various thickness are tested. The thinnest sheet is 7.9 mm, whilst the thickest sheet is 31.3 mm. A consistent analytical model is constructed for prediction of the springback, the inner sheet radius prior to and after unloading, and the smallest die width. The springback calculated by this analytical model is in all cases smaller than that found experimentally. The correspondence between theory and practice, is however, very good, although the shift in the position of the neutral axis and thinning are neglected in the theoretical analysis. Fracture did not occur in any of the conducted bending operations. It is commonly assumed that fracture in v-die bending is related to the reduction in the cross-section area at fracture, Z, in tensile testing. Z was greater than 70% for the majority of the studied materials. It is shown that particularly the mode of fracture (fracture through shear bands or by necking) should be studied in future investigations.

  • 24.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    The Influence of In-Process Variation of Blank Holding Force on Deep-Drawability1995Inngår i: Leading-Edge Manufacturing Strategies for the Metalforming Industry, Richmond Heights, Ohio, USA: PMA , 1995, s. 965-976Konferansepaper (Annet vitenskapelig)
  • 25.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    The Influence of In-Process Variation of Blank Holding Force on Deep-Drawability1993Rapport (Annet vitenskapelig)
  • 26.
    Asnafi, Nader
    Uddeholms AB, Hagfors, Sweden.
    The tool and die materials research and innovation agenda2013Inngår i: International Heat Treatment and Surface Engineering, ISSN 1749-5148, Vol. 7, nr 3, s. 101-105Artikkel i tidsskrift (Fagfellevurdert)
  • 27.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Tool Design in Cold Heading of Fasteners, Part I: Literature Survey and Analytical Modelling1995Rapport (Annet vitenskapelig)
  • 28.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Tool Design in Cold Heading of Fasteners, Part II: Finite Element Simulations and Experimental Analysis1996Rapport (Annet vitenskapelig)
  • 29.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Tools & Dies in Manufacturing of Car Bodies: Today and Tomorrow2004Konferansepaper (Annet vitenskapelig)
  • 30.
    Asnafi, Nader
    lnstitutet för Metallforskning, Stockholm, Sweden .
    Tube bending and hydroforming1999Inngår i: Svetsaren, a Welding Review, ISSN 0346-8577, Vol. 54, nr 1-2, s. 34-35Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For the production of low-weight, high-energy absorbent and cost-effective structural automotive components, the hydroforming of aluminium extrusions is now regarded as the only method in many cases. The hydroforming of aluminium extrusions has also demonstrated significant potential in other applications.

  • 31.
    Asnafi, Nader
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Tubular Hydroforming and Hydropiercing2019Inngår i: Sustainable Material Forming and Joining / [ed] R. Ganesh Narayanan & Jay S. Gunasekera, Boca Raton: CRC Press, 2019Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Hydroforming of tubular components has been known by many other names such as bulge forming of tubes, hydrobulging, internal high-pressure forming, liquid forming of tubular components, etc. Different “hydroforming” methods have been reported earlier. Hydroforming or expansion in an open and in a closed tool (Dohmann and Hartl, 1996), free and die-bound hydroforming (Schäfer Hydroforming, 1996), low, high and sequenced pressure forming (Mason, 1996; VARI-FORM, 1996), and the Rolls–Royce method (Astrop, 1968) are some of the different methods tested, used, and reported so far.

  • 32.
    Asnafi, Nader
    Luleå University of Technology, Luleå, Sweden .
    Återfjädring vid bockning längs krökta linjer1987Rapport (Annet vitenskapelig)
  • 33.
    Asnafi, Nader
    et al.
    Volvo Car Corporation, Göteborg (and Olofström), Sweden.
    Andersson, Roger
    Tubular hydroforming has arrived in Sweden: a smorgasbord of research, design, and application2001Inngår i: The Tube & Pipe Journal, Vol. 12, nr 2, s. 13-17Artikkel i tidsskrift (Fagfellevurdert)
  • 34.
    Asnafi, Nader
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Andersson, Roger
    Persson, Martin
    Liljengren, Magnus
    Comparison of Lightweight Solutions: Low Cost Production Process for High Strength Boron Steel Components2016Konferansepaper (Annet vitenskapelig)
  • 35.
    Asnafi, Nader
    et al.
    VA Automotive AB, Hässleholm, Sweden .
    Andersson, Roger
    Duroc Special Steel, Luleå, Sweden.
    Persson, Martin
    Duroc Laser Coating, Luleå, Sweden.
    Liljengren, Magnus
    Industrial Development Center, Olofström, Sweden .
    Tailored boron steel sheet component properties by selective laser heat treatment2016Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This investigation is focused on the stamping behaviour of boron steel, the properties of which are modified by selective laser heat treatment. Both CO2 and fibre lasers are tested. By using different laser processing parameters, the hardening depth in the 1 mm thick boron steel sheet Boloc 02 is varied. Four routes are tested and verified. The forming operation (in which a so-called flexrail beam is produced) in all four routes is conducted at ambient (room) temperature. The Reference route comprises stamping of the sheet. The GridBlank route starts with selective laser heat treatment of the blank, after which the blank is allowed to cool down, moved to a hydraulic press and stamped. In the GridTube route, the blank is first stamped, after which the part is moved to a laser cell and selectively laser heat treated. The fourth route, the RapidLaser route, is similar to the GridBlank route, but a higher laser speed is used to promote higher total productivity. The GridBlank route results in the highest hardness values and the best shape accuracy. The initial sheet material exhibits a hardness of 200 HV, while the parts produced in the GridBlank route exhibit a hardness of 700 HV.

  • 36.
    Asnafi, Nader
    et al.
    Swedish Institute for Metals Research, Stockholm, Sweden .
    Ekstrand, Gunnar
    Springback and Fracture in V-Die Air Bending of Thick Stainless Steel Sheets1998Rapport (Annet vitenskapelig)
  • 37.
    Asnafi, Nader
    et al.
    Swedish Institute for Metals Research, Stockholm, Sweden .
    Gabrielson, Per
    Formability of Stainless Steel and Commercially Pure Titanium Sheets in Plate Heat Exchanger Applications1997Rapport (Annet vitenskapelig)
  • 38.
    Asnafi, Nader
    et al.
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Hjelm, Sven
    Scania.
    Holmgren, Björn
    Scania.
    Malmsköld, Lennart
    Saab Automobile.
    Granström, Magnus
    AB Volvo.
    Svenningstorp, Johan
    AB Volvo.
    Mellgren, Henry
    FKG.
    2015 Sustainable Manufacturing Systems Capable of Producing Innovative Environmentally Friendly and Safe Products: R&D program proposal to secure competitive vehicle and powertrain production in Sweden2008Rapport (Annet vitenskapelig)
  • 39.
    Asnafi, Nader
    et al.
    Volvo Cars Body Components, Olofström, Sweden.
    Johansson, T.
    Volvo Cars Body Components, Olofström, Sweden.
    Miralles, M.
    Volvo Cars Body Components, Olofström, Sweden.
    Ullman, A.
    Volvo Cars Body Components, Olofström, Sweden.
    Laser surface-hardening of dies for cutting, blanking or trimming of uncoated DP6002004Inngår i: Proceedings of the International Conference on Recent Advances in Manufacture and Use of Tools and Dies and Stamping of Steel Sheets / [ed] Nader Asnafi, Olofström: Vovo Cars , 2004, s. 193-214Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this study, the methods used to harden trim dies were at the focus. Laser surface-hardening was compared to induction- and through-hardening for small and medium-size series production. The sheet materials used were 1.2 mm thick uncoated Docol 600DP and 1.95 mm thick uncoated Docol 600DL The die materials tested were Fermo, Canmo and Sleipner. This investigation showed that the optimum laser-hardening parameters must be established for each trim die material. The trim die in laser-hardened Sleipner exhibits the smallest wear, whilst the trim die in induction-hardened Fermo displays the largest wear in the semi-industrial phase of this study. The magnitude of this largest wear is, however, very small. The trim die in induction-hardened Fermo managed 100 000 strokes without any problem. The dimensional changes after laser hardening are very small. The burr height is very small, regardless of how the trim die is hardened. In this study, two sets of production trim dies were manufactured and set up. This production trim dies are used in the manufacture of V70 B-pillar Left and Right Laser hardening resulted in a lead time reduction by 5 labour days. However, the Tool & Die unit estimates that the lead time reduction obtained with laser hardening should be around 10 days under normal conditions. The cost analysis conducted by the Tool & Die unit shows that the manufacturing costs are reduced by 6%, if laser-hardening is selected. These production trim dies are and will be monitored continuously. As this paper is being written, these dies have been subject to 50 000 strokes.

  • 40.
    Asnafi, Nader
    et al.
    Volvo Cars Body Components, Olofström, Sweden.
    Kjellsson, K.
    Volvo Cars Body Components, Olofström, Sweden.
    Johansson, T.
    Volvo Cars Body Components, Olofström, Sweden.
    Blanking, stamping and trimming die experiences at volvo cars2004Inngår i: Proceedings of the International Conference on Recent Advances in Manufacture & Use of Tools & Dies and Stamping of Steel Sheets / [ed] Nader Asnafi, Olofström: Volvo Cars , 2004, s. 263-274Konferansepaper (Fagfellevurdert)
    Abstract [en]

    During the past years, large efforts have been made at Volvo Cars to establish a scientific and systematic approach to selection of die materials, hardening methods and surface treatments/coatings. These efforts were initiated, since both new higher strength sheet materials and new die materials with better performance were introduced. Both these higher strength sheet materials and higher performance die materials needed to be industrialized. At the same time, the die manufacturing and maintenance costs must be reduced. A relationship must also be established between the die materials, hardening methods and surface treatments/coatings selected on one side and the targeted volume sizes on the other. In this paper, some of the industrial cases studied at Volvo Cars will be presented. This study is, however, not completed yet The dies described in this paper (along with other dies) have been and will be monitored continuously. The authors have chosen to focus on the technology rather than the economy, particularly since the primary purpose of this paper is to share information with other technicians and discuss the feasibility of different technical solutions. Six blanking/trimming dies and seven stamping (forming) dies are presented in this paper.

  • 41.
    Asnafi, Nader
    et al.
    Industrial Development Centre, Olofström, Sweden.
    Langstedt, G.
    Linlan Composite AB, Staffanstorp, Sweden.
    Andersson, C.-H.
    Dept. of Prod. and Mat. Engineering, Lund Inst. Technol., P.O. B., Lund, Sweden; IFP, Swed. Inst. Fibre Poly. Res., P.O., Mölndal, Sweden.
    Östergren, N.
    Industrial Development Centre, Olofström, Sweden.
    Håkansson, T.
    Industrial Development Centre, Olofström, Sweden.
    New lightweight metal-composite-metal panel for applications in the automotive and other industries2000Inngår i: Thin-walled structures, ISSN 0263-8231, E-ISSN 1879-3223, Vol. 36, nr 4, s. 289-310Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new lightweight metal-composite-metal (MCM) panel is developed. This panel consists of two layers of 0.2-mm thick stainless steel sheet with a layer of woven fabric (semi-flexible composite) in between. The stiffness and the dent resistance of this MCM-panel are compared to those of corresponding panels pressed in 1-mm thick aluminum, 0.8-mm thick carbon steel and 0.8-mm thick stainless steel sheets. Compared to the aluminum panel, the MCM-panel exhibits a slightly smaller stiffness. However, the MCM-panel displays a larger dent resistance than the aluminum and the carbon steel panels. The new panel is 46% heavier than the aluminum panel. However, it is 60% lighter than the carbon and stainless steel panels. This new panel is expected to have many applications in manufacturing of parts for car, train and bus bodies, appliances and household machines. Machine chassis and air cargo containers are other examples of products, in which the new panel can be used. Production of the new panel requires that the tools be heated. The cycle time is short, since a newly developed and patented method for ultra-rapid heating of tools has been used in this study. The production is economical, since the cycle times is short and recycled fibres can be used. The production process is not completely optimized yet. However, the conducted experiments show that the panel stiffness and dent resistance are benefitted, if the tool pressure applied during the heating is low.

  • 42.
    Asnafi, Nader
    et al.
    Swedish Institute for Metals Research, Stockholm, Sweden .
    Larsson, Mats
    On Characterization of Cold Forging Properties of Steels: a New Testing Method1994Rapport (Annet vitenskapelig)
  • 43.
    Asnafi, Nader
    et al.
    Volvo Car Corporation, Olofström, Sweden.
    Lassl, G.
    Volvo Car Corporation, Olofström, Sweden.
    Olsson, B.
    Sapa Profiles.
    Nilsson, T.
    Sapa Profiles.
    Theoretical and experimental analysis of hydropiercing2003Inngår i: SAE technical paper series, ISSN 0148-7191, artikkel-id 2884Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, hydropiercing after hydroforming and prior to unloading was investigated. The primary purpose of this study was to investigate how the used hydropiercing method and the selected material and process parameters affect the hole quality. Hydropiercing inwards, hydropiercing by folding the ’scrap’ piece inwards and hydropiercing outwards were tested. The tube material was extruded AA6063-T4. The tube diameter and wall thickness were 107 mm and 2.5 mm respectively. Straight 1110-mm long tubes of this material were first hydroformed at 1300 bar and then hydropierced. Assuming that the largest (in magnitude) acceptable deflection at the hole edge is 0.2 mm, hydropiercing inwards at ≥ 1300 bar yield the best hole quality. However, the remaining scrap piece (in the tube) causes a handling problem that must be solved.

  • 44.
    Asnafi, Nader
    et al.
    Luleå University of Technology, Luleå, Sweden .
    Magnusson, Claes
    Aluminiumplåt: möjligheter att påverka formningsegenskaperna1988Inngår i: Verkstadstidningen, ISSN 0346-6434, nr 9Artikkel i tidsskrift (Fagfellevurdert)
  • 45.
    Asnafi, Nader
    et al.
    Volvo Car Corporation, Olofström, Sweden.
    Nilsson, Tomas
    Sapa Profile Bending, Vetlanda, Sweden.
    Lassl, Gunnar
    Volvo Car Corporation, Göteborg, Sweden.
    Tubular hydroforming of automotive side members with extruded aluminium profiles2003Inngår i: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 142, nr 1, s. 93-101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Side member left and side member right, which go from bumper to bumper in a car body, were at the focus in the present study. These side members were produced using straight round (hollow with a circular cross-section) extruded aluminium profiles as tube material. The tubes were bent and hydroformed. Rotary-draw bending yielded the best result. A spread within 8mm after bending was found to be acceptable provided that the bent tube was hydroformed with a high maximum internal pressure (1300bar in this study). Pressure-assisted tool closure (hydroforming tool) should be preferred. Such a tool closure prevents formation of buckles, which may be difficult to straighten out completely during hydroforming. Planeness and parallelity of the press tables and adapters play a significant role, as far as the spread and inplaneness of hydroformed components are concerned. The hydroforming tool must be matched in the press that actually will be used. Proper evacuation (of particularly air) is essential, especially in long hydroforming tools. All cross-sections must be deformed at least 2% (average perimeter enlargement) if the hydroformed components are to exhibit a reasonable spread. The critical (fracture) cross-sections predicted by finite-element simulation corresponded to those found in practice. However, the finite-element simulation was not able to predict formation of wrinkles at the tube ends caused by excessively large strokes. Such wrinkles were obtained in practice.

  • 46.
    Asnafi, Nader
    et al.
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Ocklund, Johnny
    Lassl, Gunnar
    Tubular hydroforming of side members and crash beams: a study from the perspective of Volvo Cars2002Inngår i: Information Technology, Global Environment and Sheet Metal Forming: Proceedings of the 22nd Biennial Congress, 2002, s. 289-298Konferansepaper (Annet vitenskapelig)
  • 47.
    Asnafi, Nader
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Shams, Tawfiq
    Örebro universitet, Handelshögskolan vid Örebro Universitet.
    Aspenberg, David
    DYNAmore Nordic AB, Linköping, Sweden.
    Öberg, Christina
    Örebro universitet, Handelshögskolan vid Örebro Universitet.
    3D Metal Printing from an Industrial Perspective: Product Design, Production, and Business Models2019Inngår i: Berg- und Huttenmännische Monatshefte (BHM), ISSN 0005-8912, E-ISSN 1613-7531, Vol. 164, nr 3, s. 91-100Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper is focused on automotive stamping tools and dies as well as the impact of 3D metal printing and metals related 3D-printing on design and production of such tools and dies. The purpose has been to find out the current industrial potential of 3D-printing as far as lead time, costs, shapes, material usage, metal piece size, surface roughness, hardness, strength, and machinability are concerned. The business transformational impact of 3D-printing is also addressed in this paper. The obtained results show that the lead time can be halved, the costs are somewhat higher, and the strength, hardness, surface roughness, and machinability of the 3D-printed metallic tools and dies are as good as those of the conventionally made. The maximum size of a metal piece that can be 3D-printed today by Powder Bed Fusion (PBF) is, in the best case, 500 mm × 500 mm × 500 mm. 3D-printing can also be used for the pattern to make the mold box in iron and steel casting. It is also possible to eliminate the casting pattern, since the mold box can be 3D-printed directly. All this has started to have a large business impact, and it is therefore of great significance to outline and execute an action plan almost immediately.

  • 48.
    Asnafi, Nader
    et al.
    Volvo Car Components Corp./I., Olofström, Sweden.
    Skogsgårdh, A.
    Volvo Car Components Corp./I., Olofström, Sweden.
    Theoretical and experimental analysis of stroke-controlled tube hydroforming2000Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 279, nr 1-2, s. 95-110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To select tube hydroforming instead of conventional fabrication, one has to know the tube material behaviour and tribological effects during hydroforming and how the hydroforming operation itself should be controlled. The hydroforming operation is either force- or stroke-controlled. This paper deals with stroke-controlled hydroforming. Hydroforming consists of free forming and calibration. In this paper, only the so-called free forming is treated. Stroke-controlled free forming is studied theoretically and experimentally. The theoretical part consists of analytical modeling and finite-element simulations. The conducted experiments are used to show the types of errors that might occur, when the theoretically obtained loading paths are transferred to the hydroforming equipment. The forming limit curve (FLC) is normally used as an aid/instrument in component and process design (which include finite-element simulations). The present study shows that the FLC of the tube material must be determined by hydroforming, if component and process design are to rely on this instrument.

  • 49.
    Asnafi, Nader
    et al.
    Sapa Technology, Finspång (and Vetlanda), Sweden .
    Skogsgårdh, Anders
    Skåre, Thomas
    Hydroforming av rörformiga komponenter: teori och praktik2000Konferansepaper (Annet vitenskapelig)
  • 50.
    Asnafi, Nader
    et al.
    Industrial Development Center/Volvo Cars Body Components, Olofström, Sweden .
    Skogsgårdh, Anders
    Östergren, Nicklas
    Sjöstedt, Jörgen
    HYFO98: Slutrapport1998Rapport (Annet vitenskapelig)
123 1 - 50 of 117
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf