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  • 51.
    Karlsson, Lennart
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Stensson, Annika
    Luleå tekniska universitet.
    Designing and controlling complex mechanisms1996In: Complex technical systems, Stockholm: Forskningsrådsnämnden , 1996, p. 149-161Chapter in book (Other academic)
  • 52. Karlsson, Lennart
    et al.
    Åkesson, B.
    Plane stress field induced by a concentrated heat source moving perpendicularly toward free edge of semi-infinite plate1974In: Journal of applied mechanics, ISSN 0021-8936, E-ISSN 1528-9036, Vol. 41, no 3, p. 825-827Article in journal (Refereed)
    Abstract [en]

    This study of a simplified mathematical model of the process aims at explaining the tendency of hot cracking in the weld metal near that end of a joint where the (submerged-arc) welding is finished and the welding set leaves the panel.

  • 53.
    Karlsson, Lennart
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Ökvist, M.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Design of die and its effect on wear in cup forming1995In: Simulation of materials processing: theory, methods and applications : proceedings of the fifth international conference on numerical methods in industrial forming processes, Ithaca, New York, USA, 18 - 21 June 1995 / NUMIFORM '95 / [ed] Shan-Fu Shen; Paul R Dawson, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1995, p. 587-591Conference paper (Refereed)
  • 54.
    Kyösti, Petter
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Reed, Sean
    University of Notttingham.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Andrews, John
    University of Notttingham.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Dunnett, Sarah
    Loughborough University.
    Simulation of industrial support systems in the context of functional products2011In: Proceedings of the 19th AR2TS Advances in Risk and Reliability Technology Symposium: 12 - 14 April 2011, [Swan's Nest Hotel, Stratford-upon-Avon, Nottigham: University of Nottingham , 2011Conference paper (Refereed)
  • 55. Larsson, Andreas
    et al.
    Törlind, Peter
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Bergström, Mattias
    Löfstrand, Magnus
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Design for versatility: the changing face of workspaces for collaborative design2005In: 15th International Conference on Engineering Design - ICED 05: 15 - 28 August 2005 / [ed] Andrew Samuel; William Lewis, Barton: Institution of Engineers, Australia , 2005Conference paper (Refereed)
    Abstract [en]

    In a fiercely competitive business climate, which is increasingly characterized by global alliances, partnerships and outsourcing agreements, companies struggle to decrease the negative impact of geographic distance on development efforts. The role of workspaces for collaborative design is gaining considerable attention, and there is currently an increasing interest in moving from individual tools or technologies to a more inclusive view of collaborative workspaces. This paper reports on the underlying motivation and justification for a new collaborative design studio at Luleå University of Technology, Sweden. The studio provides a rapid-response environment, in which the significance of issues raised through ethnographic observations of engineering work can be evaluated and solutions offered.

  • 56. Larsson, Andreas
    et al.
    Törlind, Peter
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Mabogunje, A.
    Leifer, L.
    Larsson, Tobias
    Elfström, Bengt-Olof
    Distributed team innovation: a framework for distributed product development2003In: Research for practice - innovation in products, processes and organisations: ICED 03, 14th International Conference on Engineering Design ; 19 - 21 August 2003, The Royal Institute of Technology, Stockholm / organized by the Royal Institute of Technology / [ed] Anders Folkeson, Glasgow: Design Research Society, 2003, p. 321-322Conference paper (Refereed)
  • 57.
    Larsson, Tobias
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Larsson, Andreas
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    A modular approach to web based multibody dynamic simulation2001In: International CIRP Design Seminar: design in the new economy : design theory, methodology and its integration with computational tools to support teams of competence - the road to wealth : 6 - 8 June, 2001 at KTH Stockholm, Sweden, Stockholm: Kungl. Tekniska Högskolan , 2001Conference paper (Refereed)
    Abstract [en]

    Computer-based tools for modelling and simulation have changed the best practise of product development. Simulation of mechanical dynamic systems have a large potential in product development but are only partly used today due to, for example, modelling complexity. A method, or tool, that supports distribution of multibody dynamic analysis models, in a modular way, is proposed and developed. Ethnographic methods have been used as a means for gaining an understanding of the engineering analysis work practice. The tool incorporates the engineering simulation packages ADAMS and MATLAB in a web based environment, and allows distributed multibody dynamic simulation in product development.

  • 58.
    Larsson, Tobias
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Larsson, Andreas
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Distributed multibody dynamic analysis within product development2001In: Proceedings of the ASME Design Engineering Technical Conference, 2001, p. 501-507Conference paper (Refereed)
    Abstract [en]

    A method that supports distribution of multibody dynamic analysis is proposed and developed. Ethnographic methods are used as a means for gaining a deeper understanding of the engineering analysis work practice, and the findings form the base for a cooperative design of the system. The concept of design rationale is applied in order to deal with current problems of engineering analysis, such as irrelevant input and output, as well as satisfying the need for useful, real-time feedback. The web based simulation environment, applied to vehicle system dynamics, contains the simulation packages ADAMS and MATLAB and incorporates database technology. The possibility to distribute simulation models and results, from simulation experts to design experts and engineers, as well as subcontractors, is created. The proposed method requires changes in the existing multibody dynamic simulation methodology regarding aspects of incorporation in product development theories

  • 59.
    Lesser, Martin
    et al.
    Luleå tekniska universitet.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Drugge, Lars
    Luleå tekniska universitet.
    Interactive model of a pantograph-catenary system1996In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 28, no suppl 1, p. 397-412Article in journal (Refereed)
    Abstract [en]

    The overhead electrification system for high speed trains is modeled by a three degree of freedom pantograph and an infinite homogeneous and elastically supported beam. Travelling wave solutions for the beam with a moving load are used to derive an equivalent stiffness for the pantograph model. The model is new in that it takes account of transverse motion due to catenary zig-zag effects. Finite element solutions are also obtained for the moving load problem. The results show that transverse zig-zag effects are the primary expected motion in this system. The calculations also show the expected importance of critical wave speeds in these systems

  • 60.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Häggblad, Hans-åke
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Josefsson, B.L.
    Chalmers University of Technology.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Thermo-mechanical FE-analysis of residual stresses and stress redistribution in butt welding of a copper canister for spent nuclear fuel2002In: Nuclear Engineering and Design, ISSN 0029-5493, E-ISSN 1872-759X, Vol. 212, no 1-3, p. 401-408Article in journal (Refereed)
    Abstract [en]

    The transient and residual temperature, stress and strain field present during electron beam welding of a plane copper end to a canister for spent nuclear fuel is calculated by the use of FEM. The subsequent stress redistribution is calculated up to 10,000 years. The canister consists of two concentric cylinders, an inner steel cylinder containing the spent nuclear fuel and an outer copper cylinder. It was found that the maximum plastic strain (plastic+creep) accumulated in the (possibly brittle) heat affected zone is ≈7%, which seems to be well below the reported ductility for the copper used.

  • 61.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Häggblad, Hans-Åke
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Josefsson, L.
    Chalmers University of Technology.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Thermo-mechanical FE-analysis of residual stresses and stress redistribution in butt welding of a copper canister for spent nuclear fuel1999In: Structural mechanics in reactor technology: transactions of the 15th International Conference on Structural Mechanics in Reactor Technology, Seoul, Korea, August 15 - 20, 1999, SMiRT 15 / [ed] Sung Pil Chang, International Association for Structural Mechanics in Reactor Technology , 1999Conference paper (Refereed)
  • 62.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsson, Mikael
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Linden, G.
    Deformations and stresses during automatic butt-welding1987In: The Effects of fabrication related stresses on product manufacture and performance: An International Conference / [ed] J.F. Alder, Cambridge: Welding Institute , 1987Conference paper (Refereed)
  • 63.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Deformations and stresses in welding of shell structures1988In: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 25, no 2, p. 635-655Article in journal (Refereed)
    Abstract [en]

    The simulation of welding of shell structures is investigated in this paper. In order to verify the implementation of the shell element adopted, two different problems were studied. In the first problem the butt-welding of two plates was simulated. In the second problem the butt-welding of a thin-walled pipe was simulated. It is concluded from the analysis of the plate problem that the shell element is quite effective in the membrane state. The comparison between calculated values and experimental values for the residual stress field in the pipe shows that the shell element performs quite well in the analysis of a realistic problem

  • 64.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Runnemalm, Henrik
    Luleå tekniska universitet.
    Hedblom, Erika
    Luleå tekniska universitet.
    Seok-Jeong, Hyun
    Developments in finite element techniques for facilitating the simulation of welding in industrial applications2001In: Mathematical modelling of weld phenomena 5: [the Fifth International Seminar on the 'Numerical Analysis of Weldability' was held in September 1999 at its usual location in Schloss Seggau near Graz, Austria] / [ed] H. Cerjak, London: Institute of Materials , 2001, p. 743-753Conference paper (Refereed)
    Abstract [en]

    Using the examples of EB welding of a copper canister (for spent nuclear fuel storage) and multirun submerged arc welding of thick steel plates, the finite element (FE) methods (2D and 3D models) developed to simulate such industrial welding applications are examined. With respect to multirun welding, challenges imposed by addition of filler material, history dependency of the material and computer resources are considered. The FE developments discussed include combined shell and solid elements, adaptive meshing, techniques for extending the FE model, and computing phase changes/material properties for low alloy steels.

  • 65.
    Lindström, John
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Löfstrand, Magnus
    Uppsala University.
    Kalhori, Vahid
    AB Sandvik Coromant, Sandviken.
    Helgoson, Martin
    AB Sandvik Coromant, Sandviken.
    Nyström, Mattias
    Masticon AB.
    Liljedahl, Bengt
    Bosch Rexroth Mellansel AB.
    Mäki, Rikard
    Volvo Construction Equipment.
    Karlsson, Lennart
    Uppsala University.
    A function innovation model for the manufacturing industry2016In: Journal of Multi Business Model Innovation and Technology, ISSN 2245-456X, Vol. 3, no 1, p. 1-28, article id 1Article in journal (Refereed)
    Abstract [en]

    The paper addresses the need for innovation in order to achieve sustainable growth and business development within the manufacturing industry, and further how that can be enabled by striving towards functions. Adopting an open perspective, the paper proposes a function innovation model involving academia, potential function providers and customers in order to create a long-term win-win situation between function providers and their customers.

  • 66.
    Lindström, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    A development process for Functional Products: hardware, software, service support system and management of operation2012In: International Journal of Product Development, ISSN 1477-9056, E-ISSN 1741-8178, Vol. 16, no 3/4, p. 284-303Article in journal (Refereed)
    Abstract [en]

    The development process for a Functional Product (FP) is complex and there is a need to coordinate, monitor, control and share information as well as to communicate properly among the parties involved in the process. This paper proposes a conceptual development process to manage the FP development, including development of hardware, software, service support system, and how to manage the operation of an FP. Further, challenges related to the integrated development of FPs are also discussed.

  • 67.
    Lindström, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Functional product development: what information should be shared during the development process?2012In: International Journal of Product Development, ISSN 1477-9056, E-ISSN 1741-8178, Vol. 16, no 2, p. 95-111Article in journal (Refereed)
    Abstract [en]

    The development process for a Functional Product (FP) is complex and there is a need to share information as well as to communicate it among the parties involved in the process. The paper concerns shared information that is of specific interest when developing FPs, in contrast to information that must be shared during a general product or service development process. The findings are compiled in a conceptual table comprising such specific information items pertaining to both the initial development as well as post development parts of an FPs lifecycle. This table can be used as an aid to any development process or method, as it points out information items that must necessarily be shared, but not how they to be shared.

  • 68.
    Lindström, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Plankina, Daria
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lideskog, Håkan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Functional product development: criteria for selection of design methods on strategic and operational levels2012In: The Philosopher's Stone for Sustainability: Proceedings of the 4th CIRP International Conference on Industrial Product-Service Systems, Tokyo, Japan, November 8th-9th, 2012 / [ed] Yoshiki Shimomura; Koji Kimita, Berlin Heidelberg: Springer Science+Business Media B.V., 2012, p. 25-30Conference paper (Refereed)
  • 69.
    Lindström, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Plankina, Daria
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Nilsson, Kent
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Parida, Vinit
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Ylinenpää, Håkan
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Functional Products: business model elements2013In: Product-Service Integration for Sustainable Solutions: Proceedings of the 5th CIRP International Conference on Industrial Product-Service Systems, Bochum, Germany, March 14th - 15th, 2013 / [ed] Horst Meier, Springer Science+Business Media B.V., 2013, p. 251-262Conference paper (Refereed)
  • 70.
    Lindström, John
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sas, Daria
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lideskog, Håkan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Löfstrand, Magnus
    Uppsala universitet.
    Karlsson, Lennart
    Defining Functional Products through their constituents2015In: International Journal of Product Development, ISSN 1477-9056, E-ISSN 1741-8178, Vol. 20, no 1, p. 1-24, article id 1Article in journal (Refereed)
    Abstract [en]

    Based on empirical studies combined with a literature review, the paper proposes a comprehensive framework defining Functional Products (FP) through their constituents. The framework adds additional specificity to the literature by identifying and discussing existing and emerging constituents of FP, shedding further light on what is needed to create a long and trustful win-win situation between providers and customers in an FP context

  • 71.
    Löfstrand, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Andrews, John
    Nottingham Transportation Engineering Centre, Faculty of Engineering, University of Nottingham.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Functional product system availability: simulation driven design and operation through coupled multi-objective optimisation2011In: International Journal of Product Development, ISSN 1477-9056, E-ISSN 1741-8178, Vol. 13, no 2, p. 119-131Article in journal (Refereed)
    Abstract [en]

    This paper describes on a conceptual level how the availability of functional products (consisting of hardware (HW) and a support system) may be simulated. The main objective of this paper is to present a simulation-driven methodology for predicting and optimising the availability and cost of functional products in both development and operation. The proposed simulation and optimisation methodology includes both HW and support system models, which coupled form a simulation model of a system (functional product) delivering the function. Two different simulation-driven methodologies are suggested in the paper: one for development and another for operation of functional products

  • 72.
    Löfstrand, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Larsson, Tobias
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    An activity based simulation approach to functional product development2006In: Challenges in collaborative engineering: CCE '06 / [ed] Leandro Soares Indrusiak, Gliwice: Interprint , 2006Conference paper (Other academic)
  • 73.
    Löfstrand, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Larsson, Tobias
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Demands on engineering design culture for implementing functional products2005In: 15th International Conference on Engineering Design - ICED 05: 15 - 28 August 2005 / [ed] Andrew Samuel; William Lewis, Barton: Institution of Engineers, Australia , 2005Conference paper (Refereed)
    Abstract [en]

    Industrial product development focused companies, such as car manufacturers, have traditionally developed and sold hardware products. In professional business-to-business relations, the integration of hardware and software with services has been identified as a shift in focus in the seller-buyer relationship from hardware development to function development and the way a sustainable economic performance could be achieved. Therefore, the common perception today of where the product is mainly hardware only, needs to be expanded to include a definition where it does not even have to have any hardware at all. Expanding the product definition therefore places additional demands on the design and development of hardware, software and services that may all be part of the functional product. Further, this article discusses how customer requirements need to be handled when developing a total offer in the form of a functional product. Finally, the traits needed in the engineer who is to develop it while being part of a multi-cultural team are discussed, possibly a geographically distributed team.

  • 74.
    Löfstrand, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Reed, Sean
    University of Notttingham.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Andrews, John
    University of Notttingham.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Dunnett, Sarah
    Loughborough University.
    Modelling and simulation of functional product system availability and support costs2012In: International Journal of Product Development, ISSN 1477-9056, E-ISSN 1741-8178, Vol. 16, no 3-4, p. 304-325Article in journal (Refereed)
    Abstract [en]

    Functional products (FP), total offers or product service systems, that comprise of both hardware (HW) and support services (SS) sold as an integrated offering under an availability guarantee, are becoming increasing popular in industry. This paper addresses, through modelling and simulation, the challenge faced by suppliers in developing an integrated HW and SS design to produce an FP which meets contracted availability. A recently published framework specified how an integrated model hardware and service support system model could be used to obtain functional availability predictions and perform simulation driven functional product development. This paper presents the first example of an integrated functional product model. It uses fault tree, Petri net and discrete event simulation techniques to enable the prediction of functional product availability and support costs. Such predictions are used here to evaluate and compare different service support system designs.

  • 75. Nybacka, Mikael
    et al.
    Larsson, Tobias
    Jeppsson, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Karlsson, Lennart
    Rantatalo, Matti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lindgren, Per
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Andren, Henrik
    Engström, Niclas
    Larsson, Roland
    Fransson, Lennart
    Hyyppä, Kalevi
    Fredriksson, Håkan
    Eriksson, Johan
    van Deventer, Jan
    Tingvall, Bror
    Project: CASTT - Centre for Automotive Systems Technologies and Testing2007Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Through the Centre for Automotive Systems Technologies and Testing, Luleå University of Technology aims to first of all support automotive winter testing in Northern Sweden. This means to support the local automotive test entrepreneurs and through them their customers: the car manufacturers and their suppliers. To succeed in this task, the center relies on the university's areas of leading research and most importantly on the cooperation between those areas.

  • 76.
    Nyström, Mattias
    et al.
    Luleå tekniska universitet.
    Larsson, Tobias
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Kokkolaras, Michael
    Papalambros, Panos Y.
    Department of Mechanical Engineering, University of Michigan.
    Linking analytical target cascading to engineering information systems for simulation-based optimal vehicle design2003In: Research for practice - innovation in products, processes and organisations: ICED 03, 14th International Conference on Engineering Design ; 19 - 21 August 2003, The Royal Institute of Technology, Stockholm / [ed] Anders Folkeson, Glasgow: Design Research Society, 2003Conference paper (Refereed)
  • 77.
    Näsström, Mats
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Wikander, L.
    Luleå tekniska universitet.
    Karlsson, Lennart
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Goldak, J.
    Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa.
    Combined solid and shell element modelling of welding1992In: Mechanical effects of welding: IUTAM symposium, Luleå/Sweden, June 10-14, 1991 / [ed] Lennart Karlsson, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 1992, p. 197-206Conference paper (Refereed)
    Abstract [en]

    Finite element calculations of residual stress distribution in a welded component from a hollow square section Inconel 600 tube are presented. Shell element can be successfully used in finite element calculations of thin walled structures. However, in the weld and the heat affected zone (HAZ) shell elements may not be sufficient, since the through thickness stress gradient is high in these regions. A combination of eight-nodes solid elements and four-nodes shell elements is used. The solid elements are used in and near the weld and shell elements are used elsewhere. This combination of solid elements and shell elements reduces the number of degrees of freedom in the problem in comparison with the use of solid elements only

  • 78.
    Oddy, A.S.
    et al.
    Carleton University, Ottawa.
    McDill, J.M.J.
    Carleton University, Ottawa.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Microstructural predictions including arbitrary thermal histories, reaustenization and carbon segregation effects1996In: Canadian metallurgical quarterly, ISSN 0008-4433, E-ISSN 1879-1395, Vol. 35, no 3, p. 275-283Article in journal (Refereed)
    Abstract [en]

    A microstructural prediction algorithm for hypoeutectoid steels is presented that accounts for carbon segregation effects and permits arbitrary thermal histories and austenite decomposition during reheating. Two austenization models are included: an instantaneous austenite formation and homogenization model; and a transient, heterogeneous austenite formation algorithm. The transient heterogeneous model predicts slightly slower formation rates than measured but compares favourably with experimental results. The two models provide upper and lower bounds for the austenization time. Predicted grain size, martensite fraction and hardness distributions are compared with measurements taken from a weld heat-affected zone (HAZ). Predictions are in good agreement with experimental results

  • 79. Pahkamaa, Andreas
    et al.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Pavasson, Jonas
    Karlberg, Magnus
    Näsström, Mats
    Goldak, John
    Carleton University, Ottawa.
    A method to improve efficiency in welding simulations for simulaton driven design2010In: Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference - 2010: presented at ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, August 15 - 18, 2010, Montreal, Quebec, Canada, New York: American Society of Mechanical Engineers , 2010, p. 1-10Conference paper (Refereed)
    Abstract [en]

    Welding is one of the most commonly used methods of joining metal pieces. In product development it is often desirable to predict residual stresses and distortions to verify that e.g., alignment tolerances, strength demands, fatigue requirements, stress corrosion cracking, etc. are fulfilled. The objective of this paper is to derive a strategy to improve the efficiency of welding simulations aiming at a (future) simulation-driven design methodology. In this paper, a weld bead deposition technique called block dumping has been applied to improve the efficiency. The proposed strategy is divided into seven steps, where the first four steps are verified by two welding simulation cases (a benchmark problem for a single weld bead-on-plate specimen and a T-welded structure). This study shows that by use of the block dumping technique, the computation time can be reduced by as much as 93% compared to moving heat source, still with acceptable accuracy of the model.

  • 80. Pahkamaa, Andreas
    et al.
    Wärmefjord, Kristina
    Institutionen för produkt- och produktionsutveckling, produktutveckling.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Söderberg, Rikard
    Institutionen för produkt- och produktionsutveckling, produktutveckling.
    Goldak, John
    Goldak Technologies.
    Combining variation simulation with welding simulation for prediction of deformation2012In: Proceedings of the ASME International Mechanical Engineering Congress and Exposition - 2010: presented at ASME 2010 International Mechanical Engineering Congress and Exposition, November 12 - 18, 2010, Vancouver, BC, Canada, New York: American Society of Mechanical Engineers , 2012, Vol. 11, p. 81-88Conference paper (Refereed)
    Abstract [en]

    In most variation simulations, i.e. simulations of geometric variations in assemblies, the influence from the heating and cooling processes, generated when two parts are welded together, is not taken into consideration. In most welding simulations the influence from geometric tolerances on parts is not taken into consideration, i.e. the simulations are based on nominal parts. In this paper these two aspects, both crucial for predicting the final outcome of an assembly, are combined by linking two commercial software packages for variation simulation and for welding simulation together. Monte Carlo simulation is used to generate a number of different non-nominal parts in the variation simulation software. The translation and rotation matrices, representing the deviations from the nominal geometry due to positioning error, are exported to the welding simulation software, where the effects from welding are applied. Thereafter, the results from the welding simulation are exported back to the variation simulation software in order to compute and illustrate the deviations and variations of the final subassembly. The method is applied on a simple case, a T-weld joint, with available measurements of residual stresses and deformations. The effect of the different sources of deviation on the final outcome is analyzed and the difference between welding simulations applied to nominal parts and to disturbed parts is investigated.

  • 81. Pahkamaa, Andreas
    et al.
    Wärmefjord, Kristina
    Department of Product and Production Development, Chalmers University of Technology.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Söderberg, Rikard
    Department of Product and Production Development, Chalmers University of Technology.
    Goldak, John
    Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa.
    Combining variation simulation with welding simulation for prediction of deformation and variation of a final assembly2012In: Journal of Computing and Information Science in Engineering, ISSN 1530-9827, E-ISSN 1944-7078, Vol. 12, no 2Article in journal (Refereed)
    Abstract [en]

    In most variation simulations, i.e., simulations of geometric variations in assemblies, the influence from heating and cooling processes, generated when two parts are welded together, is not taken into consideration. In most welding simulations, the influence from geometric tolerances on parts is not taken into consideration, i.e., the simulations are based on nominal parts. In this paper, these two aspects, both crucial for predicting the final outcome of an assembly, are combined. Monte Carlo simulation is used to generate a number of different non-nominal parts in a software for variation simulation. The translation and rotation matrices, representing the deviations from the nominal geometry due to positioning error, are exported to a software for welding simulation, where the effects from welding are applied. The final results are then analyzed with respect to both deviation and variation. The method is applied on a simple case, a T-weld joint, with available measurements of residual stresses and deformations. The effect of the different sources of deviation on the final outcome is analyzed and the difference between welding simulations applied to nominal parts and to disturbed (non-nominal) parts is investigated. The study shows that, in order to achieve realistic results, variation simulations should be combined with welding simulations. It does also show that welding simulations should be applied to a set of non-nominal parts since the difference between deviation of a nominal part and deviation of a non-nominal part due to influence of welding can be quite large

  • 82.
    Reed, Sean
    et al.
    Nottingham Transportation Engineering Centre, Faculty of Engineering, University of Nottingham.
    Andrews, John
    Nottingham Transportation Engineering Centre, Faculty of Engineering, University of Nottingham.
    Dunnett, Sarah
    Department of Aeronautical and Automotive Engineering, Loughborough University.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Modelling service support system reliability2011In: First IFAC Workshop on Advanced Maintenance Engineering, Services and Technology (2010): Lisbon, Portugal, 1 - 2 July 2010 / [ed] P. Leitao, Red Hook, NY: IFAC, International Federation of Automatic Control , 2011, p. 56-61Conference paper (Refereed)
  • 83.
    Reed, Sean
    et al.
    University of Notttingham.
    Andrews, John
    University of Notttingham.
    Dunnett, Sarah
    Loughborough University.
    Kyösti, Petter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Backe, Björn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    A modelling language for maintenance task scheduling2012In: 11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012: PSAM11, ESREL 2012, 2012, Vol. 1, p. 201-211Conference paper (Refereed)
    Abstract [en]

    This paper presents a modelling language for representing the details necessary to analyse and model the implementation of maintenance strategies for generic hardware. The maintenance strategy determines which, and when, restorations and inspections should take place whilst the scheduling of maintenance tasks implements these goals. The manner of maintenance strategy implementation therefore has important implications for maintenance cost and other performance metrics. Despite this, maintenance strategy optimisation models found in the literature lack detailed maintenance implementation models, which may lead to inaccurate and misleading results. The presented modelling language permits the representation of all common constraints and outcomes between maintenance tasks that influence task schedules. In doing so, it provides a platform for the future development of maintenance task schedule modelling, planning and decision support tools. The modelling language is demonstrated through application to part of a car braking system

  • 84.
    Reed, Sean
    et al.
    University of Notttingham.
    Andrews, John
    University of Notttingham.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    The design and modelling of maintenance during the development of functional products or product service systems2012In: Proceedings of the 1st International Conference on Through-life Engineering Services: (TESConf 2012), 5 - 6 November 2012, Cranfield University Press , 2012Conference paper (Refereed)
  • 85.
    Reed, Sean
    et al.
    University of Notttingham.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Andrews, John
    University of Notttingham.
    Service support system modelling language for simulation-driven development of functional products2013In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 11, p. 420-424Article in journal (Refereed)
    Abstract [en]

    A functional product (FP) comprises of an integrated package of hardware and support services sold under a performance-based contract. A barrier to the adoption of FP is the lack of tools for obtaining predictions of availability and support costs during product development. A previous paper by the authors described a simulation-driven development strategy for designing FP that are optimised for functional availability and support costs. This iterative strategy involves representing the FP design in a modelling language; using a software code to automatically generate and analyse a simulation model from this representation to produce detailed performance predictions; and using these predictions as feedback to improve the design. The use of a modelling language facilitates the representation of the design details within the hardware and support system that influence availability and support costs. This includes the maintenance process design, maintenance strategy design and maintenance resource availability design. In this paper, an overview of a modelling language the authors have developed for this purpose is described.

  • 86.
    Runnemalm, Henrik
    et al.
    Luleå tekniska universitet.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Finite element simulation of residual deformation induced by laser welding1997In: Proceedings: Rapid prototyping and laser applications / [ed] Dieter Roller, Croydon: Automotive automation , 1997, p. 329-335Conference paper (Refereed)
    Abstract [en]

    This paper deals with the residual deformations introduced in a thin walled pipe by laser welding. Both numerical simulations and experimental measurements have been performed. Laser welding has been adopted for an increasing number of applications. Some preferable characteristics of laser welding are high welding speed and low heat input. Laser welding of thin walled structures gives smaller residual distortions than other welding processes. One of the main objectives in this paper is to verify the theoretical finite element model by experiments. The calculated temperatures show good agreement with measured values. The calculated deformations agree fairly well with measured values except for values at the center line of the weld. Example material was steel 304.

  • 87.
    Stensson, Annika
    et al.
    Luleå tekniska universitet.
    Asplund, C.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Olinjär dynamisk analys av en framhjulsupphängning1993In: Svenska mekanikdagar 1993 : Borås 26-28 maj 1993: [sammanfattningar av föredrag], Stockholm: Svenska nationalkommittén för mekanik , 1993Conference paper (Other academic)
  • 88.
    Stensson, Annika
    et al.
    Luleå tekniska universitet.
    Asplund, Christer
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    The non-linear behaviour of a MacPherson strut wheel suspension1994In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 23, no 1, p. 85-106Article in journal (Refereed)
    Abstract [en]

    Three nonlinear models of a MacPherson strut wheel suspension have been studied. The nonlinearities considered are due to the nonlinear geometrical effects in the mechanism, the amplitude limitation due to the bumpstop, the progressive stiffness of the bumpstop and the different damping coefficients for the shock absorber in bump and rebound. The models have been derived according to physical parameter values of. the MacPherson strut wheel suspension of the car SAAB 9.000. The most suitable model was further studied with special attention to nonlinear phenomena. For harmonic forcing the system had phenomena such as multiple solutions and subharmonics. For some parameter values the solution was very sensitive to changes in the integration tolerances in the numerical integration routine. No chaotic steady state solutions were found for the parameter values studied

  • 89.
    Svoboda, Ales
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Häggblad, Hans-åke
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Simulation of hot isostatic pressing of a powder metal component with an internal core1997In: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, E-ISSN 1879-2138, Vol. 148, no 3-4, p. 299-314Article in journal (Refereed)
    Abstract [en]

    This paper presents a finite element simulation of the thermomechanical phenomena occurring during Hot Isostatic Pressing (HIP) of a powder metal component which includes a graphite core. The thermomechanical coupling is achieved in a staggered step manner. The staggered step approach considers the coupled thermomechanical response of solids, including nonlinear effects in both the thermal and mechanical analyses. The creep behaviour of the powder material during densification is modelled using the constitutive equations of thermal elasto-viscoplastic type with compressibility. The various mechanical material properties are assumed to be functions of temperature and relative density. The mechanical solution also includes large deformation and strains. The thermal problem includes temperature and relative density dependent specific heat and thermal conductivity. The constitutive equations and relations for thermal characteristics are implemented into the implicit nonlinear finite element code, PALM2D. The simulation of the HIP process of a component with internal core is chosen as an application example. The component, injection molding tool, is produced of a hot isostatically pressed stainless tool steel with an internal cavity which is achieved by inserting a graphite core into the HIP container. To verify the result of the simulation, the geometry of the capsule and the coated core are measured both before and after pressing using a computer controlled measurement machine (CMM). The measured geometry is compared with the simulated final shapes of the container and internal core. A computer-aided concurrent engineering system (CACE) is used for the complete manufacturing process from the design of the component and finite element simulation to the inspection of the final geometry.

  • 90. Troive, Lars
    et al.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Näsström, Mats
    Webster, P.
    Low, K.S.
    Finite element simulation of the bending of a flat plate to U-shaped beam cross-section and neutron diffraction determination of residual stresses1990In: Recent trends in welding science and technology: TWR '89 proceedings / [ed] Stan A. David; J.M. Vitek, Materials Park, Ohio: ASM International, 1990, p. 107-111Conference paper (Refereed)
    Abstract [en]

    Results of strains from finite element calculations and measurements by the neutron diffraction method in a hollow welded steel beam profile are presented. To calculate the residual strains, each step in the manufacturing process has to be simulated. The D-shaped beam profile is built up by a plate which is flanged into a U-cross-section profile and then welded together with a plate on the top edges. The finite element analysis includes simulation of the manufacturing of the cross-section by bending where large deformations are accounted for. Then, the finite element simulation of the welding pass follows. Plane strain conditions were assumed. The material was assumed to be thermoelastic--plastic, with temperature dependent mechanical material properties. To verify the calculations, measurements of strain were made at approx 40 points, in three orthogonal directions, using the neutron diffraction method. The neutron technique differs from the established X-ray diffraction in the way that the neutrons can penetrate substantial distances into the interior of components which the X-ray cannot. Graphs. 9 ref.-

  • 91.
    Troive, Lars
    et al.
    Luleå tekniska universitet.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Näsström, Mats
    Webster, Peter
    University of Salford, Department of Civil Engineering.
    Low, Keng S.
    University of Salford, Department of Civil Engineering.
    Finite element simulations of the bending of a flat plate to u-shaped beam cross-section and the welding to rectungular hollow cross-section and neutron diffraction determination of residual stresses1990In: Recent trends in welding science and technology: TWR '89 proceedings / [ed] Stan A. David; J.M. Vitek, Materials Park, Ohio: ASM International, 1990, p. 107-111Conference paper (Refereed)
    Abstract [en]

    Results of strains from finite element calculations and measurements by the neutron diffraction method in a hollow welded steel beam profile are presented. To calculate the residual strains, each step in the manufacturing process has to be simulated. The D-shaped beam profile is built up by a plate which is flanged into a U-cross-section profile and then welded together with a plate on the top edges. The finite element analysis includes simulation of the manufacturing of the cross-section by bending where large deformations are accounted for. Then, the finite element simulation of the welding pass follows. Plane strain conditions were assumed. The material was assumed to be thermoelastic--plastic, with temperature dependent mechanical material properties. To verify the calculations, measurements of strain were made at approx 40 points, in three orthogonal directions, using the neutron diffraction method. The neutron technique differs from the established X-ray diffraction in the way that the neutrons can penetrate substantial distances into the interior of components which the X-ray cannot.

  • 92.
    Törlind, Peter
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Larsson, Andreas
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Towards true collaboration in global design teams?2005In: 15th International Conference on Engineering Design - ICED 05: 15 - 28 August 2005 / [ed] Andrew Samuel; William Lewis, Barton: Institution of Engineers, Australia , 2005Conference paper (Refereed)
    Abstract [en]

    Today’s collaboration tools can support formal meetings to a certain extent, though there is still an immense potential for improvement when it comes to designing virtual and physical places where global design teams can collaborate in more ‘natural’ ways than existing distributed environments allow. One challenge for global product development is to support true collaboration within global design teams, where diversity and competences of the whole team can be utilized and where team members can think together rather then merely exchange information, opinions and divide work. This paper summarizes the results of several case studies and development projects performed within the Polhem Laboratory over the last four years and proposes challenges for future research. From our findings some of the most important challenges are how to support users with communication tools for more natural formal and informal communication (i.e. as a co-located team communicates), while automatically storing information and context from the distributed meetings.

  • 93. Wikander, Lars
    et al.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Oddy, Alan S.
    Luleå tekniska universitet.
    Plane thermo-mechanical finite element modelling of welding with special reference to the material behaviour1994In: International conference proceedings on modeling and control of joining processes: December 8 - 10, 1993, Orlando, Florida / [ed] Thomas Zacharia, Miami, Fla: American Welding Society , 1994, p. 517-524Conference paper (Refereed)
    Abstract [en]

    The influence of phase changes on the residual strains in a welded hollow steel beam were investigated. A D-section beam is fabricated by U-bending 6 mm thickness SS142712 plate and welding in 10 mm thickness SS142132 plate under restraint at 0.993 MJ/m heat input. Finite element analyses were used to determine residual stresses due to cold bending and for thermomechanical welding analysis. Previously published modelling was modified to include the effect of transformation induced plasticity; cross weld residual strain distribution predicted by the two models and measured experimentally were compared; discrepancies are discussed

  • 94. Wikander, Lars
    et al.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Oddy, A.S.
    Plane thermo-mechanical finite element modelling of welding with special reference to the material behaviour1993In: First International Symposium on Process Industry Piping: December 14 - 17, 1993, Orlando, Florida USA / [ed] J.E. Aller, Houston, Tex: NACE International, 1993Conference paper (Refereed)
  • 95. Wikander, Lars
    et al.
    Karlsson, Lennart
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Thermomechanical FE plane models of welding1993In: Modeling of casting, welding, and advanced solidification processes VI: proceedings of the Sixth Conference in a series on Modeling, Casting, and Welding Processes, held in Palm Coast, Florida, March 21-26, 1993 / [ed] T.S. Piwonka; Vaughan R. Voller; L. Katgerman, Warrendale, Pa: Minerals, Metals & Materials Society, 1993, p. 553-560Conference paper (Refereed)
    Abstract [en]

    Finite element simulations of welding were devised for a welded beam with a D shaped cross section. Finite element computations incorporating temperature dependant materials properties and the stresses resulting from bending the plate were compared with measurements of residual strains and stresses measured using neutron diffraction. The beam was constructed of Swedish type 142132 structural steel 6 mm in thickness, GMA welded down both sides of the beam simultaneously

  • 96.
    Wikander, Lars
    et al.
    Luleå tekniska universitet.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Näsström, Mats
    Webster, Peter
    Finite element simulation and measurement of welding residual stresses1994In: Modelling and Simulation in Materials Science and Engineering, ISSN 0965-0393, E-ISSN 1361-651X, Vol. 2, no 4, p. 845-864Article in journal (Refereed)
    Abstract [en]

    Residual strains and stresses in a hollow steel beam that had been welded to a D-shaped cross-section have been simulated by plane deformation finite element models and compared with experimental measurements obtained using the neutron diffraction strain-scanning technique. Neutron strain scanning, in contrast to other experimental techniques, is capable of measuring, accurately, non-destructively and in detail, the internal strain state at selected locations and directions within a component. This makes it a preferred method for validating model calculations of strain and stress distributions in components. In the finite element simulations a plane deformation model incorporating temperature-dependent material properties was adopted. With the assumptions for material properties that were made, the plane deformation model predicts the overall bending of the beam and the overall residual strains and stresses reasonably well. Locally, in the weld metal the predicted residual strains and stresses depend very much on the values of the thermal strain, which in one simulation include volume changes due to solid-state phase transformations. In the other simulation presented here the volume changes due to solid-state phase transformations were not accounted for.

  • 97. Åkesson, B.
    et al.
    Karlsson, Lennart
    Prevention of hot cracking in butt welds in steel panels1977In: Metal Construction, ISSN 0307-7896, Vol. 9, no 2, p. 74-77Article in journal (Refereed)
  • 98. Åkesson, B.
    et al.
    Karlsson, Lennart
    Prevention of hot cracking of butt welds in steel panels by controlled additional heating of the panels1976In: Welding Research International, ISSN 0306-9427, Vol. 6, no 5, p. 35-52Article in journal (Refereed)
    Abstract [en]

    A procedure for controlled additional heating during and after welding to prevent end cracking is devised and analyzed. The search for the optimal distribution and minimal amount of thermal energy needed for the additional heating is formulated as a mathematical programming problem. Two sided irradiation is suggested as a feasible way for transmitting the thermal energy into the panel. A case for application in a Swedish panel production line is studied. A formula for calculating the required additional heating is deduced.

12 51 - 98 of 98
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