To Örebro University

oru.seÖrebro University Publications
Change search
Refine search result
1234567 151 - 200 of 2075
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 151.
    Arunachalam, Ajay
    et al.
    Department of Computer Science, Graduate School of Applied Statistics, National Institute of Development Administration, Thailand.
    Sornil, Ohm
    Department of Computer Science, Graduate School of Applied Statistics, National Institute of Development Administration, Thailand.
    Minimizing Redundant Messages and Improving Search Efficiency under Highly Dynamic Mobile P2P Network2016In: Journal of Engineering Science and Technology Review, ISSN 1791-9320, E-ISSN 1791-2377, Vol. 9, no 1, p. 23-35Article in journal (Refereed)
    Abstract [en]

    Resource Searching is one of the key functional tasks in large complex networks. With the P2P architecture, millions of peers connect together instantly building a communication pattern. Searching in mobile networks faces additional limitations and challenges. Flooding technique can cope up with the churn and searches aggressively by visiting almost all the nodes. But it exponentially increases the network traffic and thus does not scale well. Further the duplicated query messages consume extra battery power and network bandwidth. The blind flooding also suffers from long delay problem in P2P networks. In this paper, we propose optimal density based flooding resource discovery schemes. Our first model takes into account local graph topology information to supplement the resource discovery process while in our extended version we also consider the neighboring node topology information along with the local node information to further effectively use the mobile and network resources. Our proposed method reduces collision at the same time minimizes effect of redundant messages and failures. Overall the methods reduce network overhead, battery power consumption, query delay, routing load, MAC load and bandwidth usage while also achieving good success rate in comparison to the other techniques. We also perform a comprehensive analysis of the resource discovery schemes to verify the impact of varying node speed and different network conditions.

  • 152.
    Arunachalam, Ajay
    et al.
    Department of Computer Science, School of Applied Statistics, National Institute of Development Administration, Bangkok, Thailand.
    Sornil, Ohm
    Department of Computer Science, School of Applied Statistics, National Institute of Development Administration, Bangkok, Thailand.
    Reducing Routing Overhead in random walk protocol under MP2P Network2016In: International Journal of Electrical and Computer Engineering, ISSN 2088-8708, Vol. 6, no 6, p. 3121-3130Article in journal (Refereed)
    Abstract [en]

    Due to network dynamics in self-organizing networks the resource discovery effort increases. To discover objects in unstructured peer-to-peer network, peers rely on traditional methods like flooding, random walk and probabilistic forwarding methods. With inadequate knowledge of paths, the peers have to flood the query message which creates incredible network traffic and overhead. Many of the previous works based on random walk were done in wired network. In this context random walk was better than flooding. But under MANETs random walk approach behaved differently increasing the overhead, due to frequent link failures incurred by mobility. Decentralized applications based on peer-to-peer computing are best candidates to run over such dynamic network. Issues of P2P service discovery in wired networks have been well addressed in several earlier works. This article evaluates the performance of random walk based resource discovery protocol over P2P Mobile Adhoc Network (MP2P) and suggests an improved scheme to suit MANET. Our version reduces the network overhead, lowers the battery power consumption, minimizes the query delay while providing equally good success rate. The protocol is validated through extensive NS-2 simulations. It is clear from the results that our proposed scheme is an alternative to the existing ones for such highly dynamic mobile network scenario.

  • 153.
    Arvidsson, Erik
    Örebro University, School of Science and Technology.
    Energiförbrukning för putsade, odränerade träregelväggar i fuktigt respektive torrt tillstånd2009Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In recent years, moisture damages have been noticed in rendered, undrained stud walls. The design is built on the principle one-stage tightening which means that there is no air gap in the construction. The damages have occurred when water has permeated through the rendering in leaking connections and fittings for windows, doors, canopies, balconies, terraces and awnings. Behind the plaster carrier, which consists of either polystyrene or rigid mineral wool, plasterboard has often been used as a wind protection barrier. In many cases the wind protection barrier and the underlying wooden studs have been exposed to mould and in some cases even rot. It has been shown that damp in the structure is difficult to dry out.

    The aim of the thesis has been to examine how the energy consumption is affected when this type of construction is damp, partly because energy is required to dry up damp, partly because the insulation ability for a material decreases when it is affected by moisture.

    Previous research and relevant literature has been used in this thesis, to provide: A comprehensive picture of the problem, an explanation for the calculations used and an understanding of the conclusions drawn.

    The energy consumption has been calculated for 1 m2 wall area on two types of wall designs. The calculations have been performed in both dry and damp condition. To calculate the energy consumption in damp condition, three different types of calculation models have been used in three different ways. Since no measurements have been made, the calculations are to some extent based on assumed values.

    The amount of damp that have entered the structure has, according to the calculation models used, been shown to produce small differences in energy consumption compared to the dry structure. The main problem for these types of walls seems instead to be the growth of microorganisms. Nevertheless, the microorganisms seem not to have affected the indoor environment in any significant manner.

    Download full text (pdf)
    FULLTEXT01
  • 154.
    Arvidsson, Erik
    et al.
    Örebro University, School of Science and Technology.
    Larsson, Tord
    Örebro University, School of Science and Technology.
    Stridh, Göran
    Örebro University, School of Science and Technology.
    Energiförluster i partiellt fuktiga enstegstätade ytterväggskonstruktioner: tema: fasader och fönster2009In: Bygg och Teknik, ISSN 0281-658X, E-ISSN 2002-8350, no 8, p. 28-32Article in journal (Other academic)
  • 155.
    Arén, Björn
    Örebro University, Department of Technology.
    Die Stresses in the compaction of powders: experiments and analysis2004Conference paper (Refereed)
  • 156.
    Arén, Björn
    Örebro University, School of Science and Technology.
    Dimensionering efter hållfasthet av olika slag2009In: Uppfinnaren & konstruktören, ISSN 0284-9682, no 5, p. 32-34Article in journal (Other (popular science, discussion, etc.))
  • 157.
    Arén, Björn
    Örebro University, Department of Technology.
    Dimensioning of dies for the compaction of shaped PM-parts2003Conference paper (Refereed)
  • 158.
    Arén, Björn
    Örebro University, School of Science and Technology.
    Utveckling - är att se, söka och förverkliga: kursbok i produktutveckling2010 (ed. 1)Book (Other academic)
  • 159.
    Asaad Sharif Elemara, Hadil
    Örebro University, School of Science and Technology.
    GRUNDLÄGGNINGSMETODER-VAL AV GRUNDLÄGGNINGSMETOD FÖR SMÅHUS I ÖREBRO LÄN2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Foundations support entire houses and are required to be adequately well-built to carry a building’s

    mass for many years without facing problems due to environmental impacts such as moisture and

    frost. This work covers three basic types of foundations; concrete slab, crawl space and block

    foundation. The aim of this work is to investigate the construction methods of the foundations

    mentioned above, which are used within the construction of single-family homes in the city of

    Örebro, Sweden. Additionally, the basis of selection of these foundations by various construction

    companies in respect to risk of moisture-related problems is examined.

    Information about the foundations is collected from scholarly literature as well as qualitative

    interviews with seven construction companies’ experts. Ultimately, this study found that concrete

    slab with underlying insulation is more commonly used within the construction of single-family

    homes in Örebro than the other alternatives. Operators find that this foundation has many

    advantages in comparison with the other foundation techniques.

    Download full text (pdf)
    fulltext
  • 160.
    Asadi, Sahar
    et al.
    Örebro University, School of Science and Technology.
    Badica, Costin
    University of Craiova, Craiova, Romania.
    Comes, Tina
    Karslruhe Institute of Technology, Karslruhe, Germany.
    Conrado, Claudine
    Thales Research and Technology, Delft, The Netherlands.
    Evers, Vanessa
    University of Amsterdam, Amsterdam, The Netherlands.
    Groen, Frans
    University of Amsterdam, Amsterdam, The Netherlands.
    Illie, Sorin
    University of Craiova, Craiova, Romania.
    Steen Jensen, Jan
    Danish Emergency Management Agency (DEMA), Birkerød, Denmark.
    Lilienthal, Achim J.
    Örebro University, School of Science and Technology.
    Milan, Bianca
    DCMR, Delft, The Netherlands.
    Neidhart, Thomas
    Space Applications Services, Zaventem, Belgium.
    Nieuwenhuis, Kees
    Thales Research and Technology, Delft, The Netherlands.
    Pashami, Sepideh
    Örebro University, School of Science and Technology.
    Pavlin, Gregor
    Thales Research and Technology, Delft, The Netherlands.
    Pehrsson, Jan
    Prolog Development Center, Brøndby Copenhagen, Denmark.
    Pinchuk, Rani
    Space Applications and Services, Zaventem, Belgium.
    Scafes, Mihnea
    University of Craiova, Craiova, Romania.
    Schou-Jensen, Leo
    DCMR, Brøndby Copenhagen, Denmark.
    Schultmann, Frank
    Karslruhe Institute of Technology, Karlsruhe, Germany.
    Wijngaards, Niek
    Thales Research and Technology, Delft, the Netherlands.
    ICT solutions supporting collaborative information acquisition, situation assessment and decision making in contemporary environmental management problems: the DIADEM approach2011In: Proceedings of the 25th EnviroInfo Conference "Environmental Informatics", Herzogenrath: Shaker Verlag, 2011, p. 920-931Conference paper (Refereed)
    Abstract [en]

    This paper presents a framework of ICT solutions developed in the EU research project DIADEM that supports environmental management with an enhanced capacity to assess population exposure and health risks, to alert relevant groups and to organize efficient response. The emphasis is on advanced solutions which are economically feasible and maximally exploit the existing communication, computing and sensing resources. This approach enables efficient situation assessment in complex environmental management problems by exploiting relevant information obtained from citizens via the standard communication infrastructure as well as heterogeneous data acquired through dedicated sensing systems. This is achieved through a combination of (i) advanced approaches to gas detection and gas distribution modelling, (ii) a novel service-oriented approach supporting seamless integration of human-based and automated reasoning processes in large-scale collaborative sense making processes and (iii) solutions combining Multi-Criteria Decision Analysis, Scenario-Based Reasoning and advanced human-machine interfaces. This paper presents the basic principles of the DIADEM solutions, explains how different techniques are combined to a coherent decision support system and briefly discusses evaluation principles and activities in the DIADEM project.

    Download full text (pdf)
    fulltext
  • 161.
    Asadi, Sahar
    et al.
    Örebro University, School of Science and Technology.
    Pashami, Sepideh
    Örebro University, School of Science and Technology.
    Loutfi, Amy
    Örebro University, School of Science and Technology.
    Lilienthal, Achim J.
    Örebro University, School of Science and Technology.
    TD Kernel DM+V: time-dependent statistical gas distribution modelling on simulated measurements2011In: Olfaction and Electronic Nose: proceedings of the 14th International Symposium on Olfaction and Electronic Nose (ISOEN) / [ed] Perena Gouma, Springer Science+Business Media B.V., 2011, p. 281-282Conference paper (Refereed)
    Abstract [en]

    To study gas dispersion, several statistical gas distribution modelling approaches have been proposed recently. A crucial assumption in these approaches is that gas distribution models are learned from measurements that are generated by a time-invariant random process. While a time-independent random process can capture certain fluctuations in the gas distribution, more accurate models can be obtained by modelling changes in the random process over time. In this work we propose a time-scale parameter that relates the age of measurements to their validity for building the gas distribution model in a recency function. The parameters of the recency function define a time-scale and can be learned. The time-scale represents a compromise between two conflicting requirements for obtaining accurate gas distribution models: using as many measurements as possible and using only very recent measurements. We have studied several recency functions in a time-dependent extension of the Kernel DM+V algorithm (TD Kernel DM+V). Based on real-world experiments and simulations of gas dispersal (presented in this paper) we demonstrate that TD Kernel DM+V improves the obtained gas distribution models in dynamic situations. This represents an important step towards statistical modelling of evolving gas distributions.

    Download full text (pdf)
    fulltext
  • 162.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    3D Metal Printing from an Industrial Perspective: Product Design, Production and Business Models2018Conference paper (Refereed)
    Abstract [en]

    This paper summarizes the current position of 3D metal printing/additive manufacturing (henceforth called 3D metal printing) from an industrial perspective. The new possibilities to design the part differently simply because the new shape can be produced and which provides benefits with respect to improved material utilization degree, reduced weight, size etc. are addressed in this paper. Different types of generative design concepts such as form synthesis, topology optimization and lattice and surface optimization are exemplified. Low volume production by 3D metal printing is discussed. High volume production by 3D metal printing of manufacturing tools and dies is described.

    Tool & die production is an important phase in the development of new components/product models. This phase determines both the lead time (Time-To-Production/-Market) and the size of the investments required to start the production. The lead time for the production of tools and dies for a new car body is currently about 12 months and needs to be reduced 40% by 2020. The lead time for injection molds for small and large series production must be reduced to 10 days and 4 weeks respectively. Lead time and cost-efficient metallic tools can be provided by 3D metal printing. This paper focuses on tools and dies for the manufacture of sheet metal & plastic components for the engineering, automotive and furniture industries. The paper includes Powder Bed Fusion (PBF). Digitalization through virtual tool & die design and optimization of the tool & die production combined with the PBF´s digital essence provides greater flexibility, better efficiency, tremendous speed, improved sustainability and increased global competitiveness.

    3D metal printing is expected to result in several changes in the supplier chain and generate new business models. The present paper describes some of the changes 3D metal printing has led to and is expected to result in within the engineering and automotive industry in Europe during the coming years.

  • 163.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    3D Metal Printing from an Industrial Perspective: Product Examples, Production and Business Models2018Conference paper (Refereed)
    Abstract [en]

    This paper summarizes the current position of 3D metal printing/additive manufacturing (henceforth called 3D metal printing) by the so-called Powder Bed Fusion (PBF) from an industrial perspective, particularly in Sweden.

    The new possibilities to design the part differently simply because the new shape can be produced and which provides benefits with respect to improved material utilization degree, reduced weight, size etc. are addressed in this paper.

    Tool & die production is an important phase in the development of new components/product models. This phase determines both the lead time (Time-To-Production/‐Market) and the size of the investments required to start the production. The lead time for the production of tools and dies for a new car body is currently about 12 months and needs to be reduced 40% by 2020. The lead time for injection molds for small and large series production must be reduced to 10 days and 4 weeks respectively. Lead time and cost-efficient metallic tools can be provided by 3D metal printing. This paper focuses on tools and dies for the manufacture of sheet metal & plastic components for the engineering and automotive industries.

    Digitalization through virtual tool & die design and optimization of the tool & die production combined with the PBF´s digital essence provides greater flexibility, better efficiency, tremendous speed, improved sustainability and increased global competitiveness.

    3D metal printing is expected to result in several changes in the supplier chain and generate new business models. The present paper describes some of the changes 3D metal printing has led to and is expected to result in within the engineering and automotive industry during the coming years.

  • 164.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    3D Metal Printing of Industrial Tools & Dies2019Conference paper (Other academic)
    Abstract [en]

    Tool & die production is an important phase in the development of new components/product models. This phase determines both the lead time (Time-To-Production/-Market) and the size of the investments required to start the production. This paper is focused on Powder Bed Fusion (PBF) and summarizes the current position of 3D metal printing/additive manufacturing (henceforth called 3D metal printing)of industrial tools & dies. It also exhibits the new possibilities to design the tool/die differently simply because the new shape can be produced. Different types of generative design concepts such as form synthesis, topology optimization and lattice and surface optimization are exemplified. The paper exemplifies business cases, the shorter lead times, the associated improved material utilization degree, reduced weight,etc. Low volume production by 3D metal printing is discussed. High volume production by 3D metal printing of manufacturing tools and dies is described. The paper exhibits some examples of digitalization through virtual tool & die design and optimization of the tool& die production and how it provides greater flexibility, better efficiency, tremendous speed, improved sustainability and increased global competitiveness. 3D metal printing is expected to result in several changes in the supplier chain and generate new business models. The present paper describes some of the changes 3D metal printing has led to and is expected to result in within the engineering and automotive industry in Europe during the coming years.

  • 165.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    3D Metal Printing of Production Tools & Dies2018Conference paper (Refereed)
    Abstract [en]

    3D metal printing is of great interest for manufacturing of tools and dies for high volume production. It is possible to accomplish lead time reduction, tool and die weight saving, improved cycle time etc. The presentation deals primarily with Powder Bed Fusion as 3D printing method and describes 3D metal printing of tools & dies both scientifically and from an industrialization perspective. The presentation shows how far we have come in industrialization of 3D metal printing of tools & dies and what needs to be done to include 3D metal printing in the existing industrial systems and infrastructure.

  • 166.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    3D Printing / Additative Manufacturing from Product Creator and Tool Maker Perspectives in the Automotive Industry2016Conference paper (Other academic)
  • 167.
    Asnafi, Nader
    VA Automotive AB, Hässleholm, Sweden .
    3D-printning från produktskapares och verktygsmakares perspektiv2015Conference paper (Other academic)
  • 168.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    3rd International Conference on Material Engineering and Advanced Manufacturing Technology, 26–28 April 2019, Shanghai, China2020Conference proceedings (editor) (Refereed)
    Abstract [en]

    We are very pleased to present the proceedings of the 3rd International Conference on Material Engineering and Advanced Manufacturing Technology (MEAMT 2019) that was held successfully under the auspices of IASED in Shanghai, China, April 26-28, 2019.

    The theme of the conference - Material Engineering and Advanced Manufacturing Technology - is of key importance to the science and technology and a sustainable industrial development. This conference promotes valuable contacts between academia and industry and addresses both basic research and the societal/industrial technological needs within Material Engineering and Advanced Manufacturing Technology.

    In this era of Industry 4.0, we hope that the conference provided applicable data/information, addressed the issues in the societal/industrial transformation, and facilitated exchange within and between academia and industry.

    We want to express our gratitude to the program chairs and all members of the advisory, publicity, and technical committees for their valuable time and advices. We are grateful to the world renowned scientists who acted as keynote speakers at the conference.

    After a rigorous review process, where each paper was reviewed by at least two reviewers, high quality papers were accepted for presentation at this conference. We would like to thank all the reviewers for their time, effort, and for completing their assignments on time albeit tight deadlines.

    Many thanks to the authors for their valuable contributions and to the attendees for their active participation.

    Finally, a big thank to the organizers who made this conference to yet another unforgettable experience.

    Nader Asnafi

    Professor of Mechanical Engineering, Örebro University, Sweden Editor of the proceedings of MEAMT 2019 One behalf of the conference committee.

  • 169.
    Asnafi, Nader
    Sapa Technology, Finspång (and Vetlanda), Sweden.
    Analytical modelling of the forces and pressures required in hydropiercing2000Report (Other academic)
  • 170.
    Asnafi, Nader
    Volvo Car Components Corporation/Industrial Development Centre, Olofström, Sweden.
    Analytical modelling of tube hydroforming1999In: Thin-walled structures, ISSN 0263-8231, E-ISSN 1879-3223, Vol. 34, no 4, p. 295-330Article in journal (Refereed)
    Abstract [en]

    The automotive industry has shown a growing interest in tube hydroforming during the past years. The advantages of hydroforming (less thinning, a more efficient manufacturing process etc.) can, for instance, be combined with the high strength of extra high strength steels, which are usually less formable, to produce structural automotive components which exhibit lower weight and improved service performance. Design and production of tubular components require knowledge about tube material behaviour and tribological effects during hydroforming and how the hydroforming operation itself should be controlled. These issues are studied analytically in the present paper. Hydroforming consists of free forming and calibration. Only the so-called free forming is treated here. The analytical models constructed in this paper are used to show what the limits are during the free forming, how different material and process parameters influence the loading path and the forming result, and what an experimental investigation into hydroforming should focus on. The present study was a part of a larger investigation, in which finite-element simulations and experiments were also conducted. The results of these simulations and experiments will be accounted for in coming papers.

  • 171.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Application of Laser-based Powder Bed Fusion - Current Possibilities and Constraints for Tooling2021Conference paper (Refereed)
    Abstract [en]

    The current possibilities and constraints for tooling made by the application of Laser-based Powder Bed Fusion (L-PBF) is at the focus of this presentation. Design and manufacturing of production tools & dies for cold and hot working and injection molding are addressed. Solid and topology optimized tools are tested, compared with the conventionally designed and manufactured version of the same tools, and certified. The current possibilities and constraints are addressed from the material, technological and industrial perspectives. The current manufacturing readiness level and the industrialization status of metal additive manufacturing through L-PBF are evaluated.

  • 172.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Application of Laser-Based Powder Bed Fusion for Direct Metal Tooling2021In: Metals, ISSN 2075-4701, Vol. 11, no 3, article id 458Article in journal (Refereed)
    Abstract [en]

    The journey of production tools in cold working, hot working, and injection molding from rapid tooling to additive manufacturing (AM) by laser-based powder bed fusion (L-PBF) is described. The current machines and their configurations, tool steel powder materials and their properties, and the L-PBF process parameters for these materials are specified. Examples of production tools designed for and made by L-PBF are described. Efficient design, i.e., high tooling efficiency and performance in operation, should be the primary target in tool design. Topology and lattice structure optimization provide additional benefits. Using efficient design, L-PBF exhibits the greatest potential for tooling in hot working and injection molding. L-PBF yields high tooling costs, but competitive total costs in hot working and injection molding. Larger object sizes that can be made by L-PBF, a larger number of powder metals that are designed for different tooling applications, lower feedstock and L-PBF processing costs, further L-PBF productivity improvement, improved surface roughness through L-PBF, and secured quality are some of the targets for the research and development in the future. A system view, e.g., plants with a high degree of automation and eventually with cyber-physically controlled smart L-PBF inclusive manufacturing systems, is also of great significance.

  • 173.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden.
    Automotive Tools & Dies - Volvo Cars Perspective2007Conference paper (Other academic)
  • 174.
    Asnafi, Nader
    Sapa Technology, Finspång (and Vetlanda), Sweden .
    Automotive Tubular Hydroforming: Fundmentals and Industrial Practice2000Conference paper (Other academic)
  • 175.
    Asnafi, Nader
    VA Automotive AB, Hässleholm, Sweden .
    Automotive/Car Body Stamping Tools & dies: 3D Printing Offers Shorter Lead Time and Reasonable Costs2016Conference paper (Other academic)
  • 176.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Design and Additive Manufacturing of Tools for Forming and Trimming of up to 2-mm Thick DP6002020In: Current Trends in Sheet Metal Forming: Abstracts, 2020Conference paper (Refereed)
    Abstract [en]

    Design and manufacturing of stamping tools and dies are two important steps in the development of new components/products. These steps determine both the lead time (Time-To-Production/-Market) and the size of the investments required to start the production. 

    This paper deals with the design and production of stamping tools & dies for sheet metal components in up to 2-mm thick hot-dip galvanized DP600. Laser-based Powder Bed Fusion (LPBF) is the additive manufacturing (henceforth even called 3D printing) method used to make these tools and dies.

    The stamping tools & dies should withstand the requirements set in stamping of hot-dip galvanized DP600. Solid and topology optimized forming and cutting/blanking/trimming tools made in maraging steel (DIN 1.2709) by LPBF were subject to certification (approval/disapproval) for stamping of 2-mm thick hot-dip galvanized DP600. A working station in an industrial progressive die used for stamping of 1-mm thick DP600 was 3D-printed in DIN 1.2709, both with a honeycomb inner structure and after topology optimization, with successful results. 3D printing results in approved sheet metal parts, a significant lead time reduction and improved tool material efficiency. The 3D-printed tools and dies display acceptable wear behaviour. The cost for 3D-printed stamping tools and dies is, however, higher than the cost of those made conventionally. This cost increase can be accepted for the so-called late changes. This presentation is an account of the above-mentioned investigations.

    Download full text (pdf)
    Current Trends in Sheet Metal Forming. Abstracts
  • 177.
    Asnafi, Nader
    Jönköping University, Jönköping, Sweden .
    Development of Sustainable Products and Manufacturing/Production2014Conference paper (Other academic)
  • 178.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Digitalization of the Swedish Industry2018Conference paper (Refereed)
  • 179.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Digitalization of the Swedish Industry2018Conference paper (Refereed)
  • 180.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Direct Rapid Tooling by Laser-based Powder Bed Fusion2021Conference paper (Refereed)
    Abstract [en]

    Additive manufacturing of production tools through laser-based powder bed fusion is at the focus of this presentation. Design and manufacturing of production tools & dies for stamping of sheet metal parts, cores (inserts) for injection moulding of plastic components and other types of production tools are addressed. Solid and topology optimized tools are tested, compared with the conventionally designed and manufactured version of the same tools, and certified. The current possibilities and constraints are addressed from the materials and technological perspectives. The current manufacturing readiness level and the industrialization status of metal additive manufacturing of tooling through laser-based powder bed fusion are evaluated.

  • 181.
    Asnafi, Nader
    Luleå University of Technology, Luleå, Sweden .
    Formbarhet under dragpressning, sträckpressning och bockning samt egenskaper efter formning av aluminiumplåt1988Report (Other academic)
  • 182.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Forming of Aluminium2002Conference paper (Other academic)
  • 183.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Hydroformability of Extra High Strength Steels in Structural Tubular Applications: an Analysis based on Literature Survey1997Report (Other academic)
  • 184.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Improved Lightweight Manufacturing Flexibility by Stamping of Selectively Laser Heat Treated Boron Steel Sheet2016Conference paper (Other academic)
  • 185.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Innovative Lead Time and Cost Efficient Tools and Dies for Lightweight Autobody Components2016Conference paper (Other academic)
  • 186.
    Asnafi, Nader
    Uddeholms AB, Hagfors, Sweden .
    Kunddriven produktutveckling på en varierad marknad för global framgång2012Conference paper (Other academic)
  • 187.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Manufacturing the car body of tomorrow2002Conference paper (Other academic)
  • 188.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Metal Additive Manufacturing – State of the Art 2020: A special issue of Metals2021Collection (editor) (Refereed)
    Abstract [en]

    Additive manufacturing (AM), more popularly known as 3D printing, comprises a group of technologies used to produce objects through the addition (rather than removal) of material. AM is used in many industries—aerospace and defense, automotive, consumer products, industrial products, medical devices, and architecture. AM is transforming the industry, and this industrial transformation is expected to become more comprehensive and reach a higher pace during the coming years.

    Additive manufacturing of metal components with virtually no geometric limitations has enabled new product design options and opportunities, increased product performance, shorter cycle time in part production, total cost reduction, shortened lead time, improved material efficiency, more sustainable products and processes, full circularity in the economy, and new revenue streams.

    This Special Issue of Metals focuses on metal additive manufacturing with respect to the topics mentioned below (please see the Keywords/Topics below). The papers presented in this Special Issue give an account of the 2020 scientific, technological, and industrial state of the art for metal additive manufacturing from different perspectives (see the Keywords/Topics below). Your contribution to this 2020 account is highly valuable and appreciated. 

    The submitted contribution should address metal additive manufacturing with respect to one or several of the following topics:

    • Business models and engineering
    • Product/component design (including generative design, topology optimization, lattice and surface optimization, etc.)
    • Industrial applications (aerospace, defense, automotive, consumer, medical, and industrial products, etc.)
    • Material and process design and engineering
    • New materials
    • Powder production and characterization
    • Systems and equipment engineering
    • Post-processing
    • Process control and optimization and quality assurance

  • 189.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Metal Additive Manufacturing of Production Tools through Laser-based Powder Bed Fusion - Current Possibilities and Constraints2021Conference paper (Refereed)
    Abstract [en]

    Invited keynote speech

    Additive manufacturing of production tools through laser-based powder bed fusion is at the focus of this keynote presentation. Design and manufacturing of production tools & dies for stamping of sheet metal parts, cores (inserts) for injection moulding of plastic components, and other types of production tools are addressed. Solid and topology optimized tools are tested, compared with the conventionally designed and manufactured version of the same tools, and certified. The current possibilities and constraints are addressed from the material, technological and business perspectives. The current manufacturing readiness level and the industrialization status of metal additive manufacturing through laser-based powder bed fusion are evaluated.

  • 190.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Metal Additive Manufacturing of Production Tools through Laser-based Powder Bed Fusion - Current Possibilities and Constraints2020Conference paper (Refereed)
    Abstract [en]

    Additive manufacturing of production tools through laser-based powder bed fusion is at the focus of this presentation. Design and manufacturing of production tools & dies for stamping of sheet metal parts, cores (inserts) for injection moulding of plastic components and other types of production tools are addressed. Solid and topology optimized tools are tested, compared with the conventionally designed and manufactured version of the same tools, and certified. The current possibilities and constraints are addressed from the material, technological and business perspectives. The current manufacturing readiness level and the industrialization status of metal additive manufacturing through laser-based powder bed fusion are evaluated.

  • 191.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Metal Additive Manufacturing/3D Metal Printing in the Circular Economy2018Conference paper (Refereed)
  • 192.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Metal Additive Manufacturing—State of the Art 20202021In: Metals, ISSN 2075-4701, Vol. 11, no 6, article id 867Article in journal (Refereed)
    Download full text (pdf)
    Metal Additive Manufacturing—State of the Art 2020
  • 193.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Nya material och processer vid framtagning av lättviktskarosser2004Conference paper (Other academic)
  • 194.
    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 Material1992Conference paper (Other academic)
  • 195.
    Asnafi, Nader
    Gränges Technology, Finspång, Sweden.
    On springback of double-curved autobody panels2001In: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 43, no 1, p. 5-37Article in journal (Refereed)
    Abstract [en]

    The springback of double curved autobody panels is studied theoretically and experimentally. Both steel and aluminum sheets are included in this investigation. The obtained results show that the springback is decreased with increasing binder force, increasing curvature, increasing sheet thickness and decreasing yield strength. This paper comprises also a discussion on the plastic strains and their influence on the springback.

  • 196.
    Asnafi, Nader
    Industrial Development Center/Volvo Cars Body Components, Olofström, Sweden .
    On Springback of Double-Curved Autobody Panels1998In: Proceedings, working groups meeting - IDDRG, International Deep Drawing Research Group: Genval, Benelux, June 15 - 16, 1998, 1998Conference paper (Other academic)
  • 197.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    On Springback of Double-Curved Autobody Panels, Part I: Theoretical Treatment1996Report (Other academic)
  • 198.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    On Springback of Double-Curved Autobody Panels, Part II: Experimental Analysis1996Report (Other academic)
  • 199.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden .
    On strength, stiffness and dent resistance of car body panels1995In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 49, no 1-2, p. 13-31Article in journal (Refereed)
    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.

  • 200.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    On Strength, Stiffness and Dent Resistance of Car Body Panels1993Report (Other academic)
1234567 151 - 200 of 2075
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf