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  • 1.
    Ericson Öberg, Anna
    et al.
    Chalmers, Gothenburg, Sweden.
    Åstrand, Erik
    University West, Department of Engineering Science, Research Enviroment Production Technology West. Volvo Construct Equipment, Braås, Sweden.
    Improved productivity by reduced variation in gas metal arc welding (GMAW)2017In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 92, no 1-4, p. 1027-1038Article in journal (Refereed)
    Abstract [en]

    The purpose of the research conducted is to describe the consequences of variation in the welding industry and the effect it has on manufacturing productivity. The potential has shown to be hidden in unnecessarily stringent requirements and over-processing. This has been studied in steps: customer requirements, design and analysis, preparation, welding, and assessment. The effect of variation in each step has been analyzed including estimations of its productivity improvement potential. Theoretically, in a perfect situation, with customized requirements and eliminated variation, more than half of all welding could be removed. Such a reduction is certainly neither practical nor possible. However, a sensible, controlled reduction could still have a very high impact. The financial implications are therefore substantial. The improved productivity of the manufacturing resources could be used for business development and increased production. To be able to realize the potential, interdisciplinary efforts are necessary. Management across different functions need to agree on the intended product life and make decisions thereafter.

  • 2. Holmstrand, T
    et al.
    Mrdjanov, N.
    Barsoum, Z.
    Åstrand, Erik
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Fatigue life assessment of improved joints welded with alternative welding techniques2014In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 42, no July, p. 10-21Article in journal (Refereed)
    Abstract [en]

    In this study, the fatigue life improvement by adopting the toe weaving technique on nonload carrying cruciform welded joints has been investigated. Fatigue testing was conducted on two batches of specimens welded using double-pass manual welding. One batch had a straight second pass and the other was weaved. The influence of different weaving shape parameters was analyzed by performing crack growth analyses. The fatigue testing shows a slightly improved fatigue life for the two different batches compared to as-welded joints; the improvement is similar for both batches. The crack growth analysis concludes that the batch with the straight second pass should provide slightly higher fatigue life compared to the toe weaved batch. Measurements show a presence of undercuts in the vicinity of the crack initiation site. Nonetheless, an increased fatigue life is obtained, due to the low flank angle created during welding of the second pass, which reduces the stress concentration in the weld toe, prolonging the fatigue life.

  • 3.
    Åstrand, Erik
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    A Framework for optimised welding of fatigue loaded structures: Applied to gas metal arc welding of fillet welds2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Welding is a key process for heavy steel structures, but it is also a weak link in the structure since fatigue fractures in welds are a common cause of failure. This thesis proposes several changes in order to improve the fatigue properties in acost effective way, enabling reduced weight and reduced cost of welded structures. The main idea is to adapt the weld requirements and welding procedures to the load conditions of the weld. This approach ensures that the main focus in the welding process is the critical characteristics of the welds fatigue life properties. The fatigue life critical properties are most often related to the geometrical factors of the weld such as the radius at the weld toe or the penetration in the root. The thesis describes a holistic view of the subject and covers fatigue, weld quality, weld requirements and welding procedures. It becomes evident that the traditional way of working without a direct connection to fatigue is not the best. With an adaptation to the load conditions and fatigue, it is possible to enhance the fatigue life and reduce the welding cost. The main challenge is to connect the welding process, weld requirements and fatigue life properties. It is needed for an optimised welding process of heavy structures subjected to fatigue and toget a predictable fatigue life. Welds optimised for enhanced fatigue life properties are not necessary accepted according to the requirements in a current standard. Several welding procedures are proposed for improving the fatigue life properties of the weld, which indicate a high potential for enhanced fatigue lifeof fillet welds. The idea is to replace the "standard" fillet weld with three different weld types: (i) Welds with deep penetration, (ii) Welds with large weld toe radius and (iii) Welds produced with low cost. Together with customised requirements and reduced over-welding there is a vast potential for reduced weight, reduced cost and increased productivity.The main contribution of this thesis work is the cross-functional studies including design, analysis, production and quality control. This gives a framework for improvements supporting reduced cost and reduced weight of VIII welded structures without reducing the fatigue strength. Many shortcomings have been highlighted to change the welding from a state where welds are done in a way as they "always" have, by tradition, to a more contemporary situation where weld requirements and welding procedures are actively chosen to match the load conditions of the weld. This result in requirements and welding procedures which actually are connected to the fatigue properties as defined by the loading conditions, and where auditors with high probability can say that an accepted weld actually is better than a rejected weld.

  • 4.
    Åstrand, Erik
    University West, Department of Engineering Science, Research Environment Production Technology West. University West, Department of Engineering Science, Research Enviroment Production Technology West. Volvo Construction Equipment, Carl Lihnells väg, Braås, Sweden .
    A new innovative toolbox for lean welding of fatigue loaded structures2015In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 81, no 1-4, p. 635-643Article in journal (Refereed)
    Abstract [en]

    Welding is a key manufacturing technology in the production of heavy steel structures, but it is likewise a weak link in the production chain since fatigue fractures in welds is a common cause of failures. This paper proposes several changes in the process to make the manufacturing more efficient and to improve the fatigue properties. The idea is to adopt the weld quality demands for the purpose of the weld and to connect them to the welding procedures. This approach ensures that the primary focus during welding is at the critical characteristics which add value to the welded structure through an enhanced fatigue life. These fatigue life-critical properties have been found to be related to the local weld geometry in the weld toe and at the weld root. Traditional demands related to the good workmanship of welding can often be neglected, due to its limited effect to the fatigue life. The research presented in this paper has contributed to the development of welding procedures for improved fatigue life properties at the critical points of the weld. Results indicate a considerable potential for enhanced fatigue life of fillet welds. The idea is to replace the standard fillet welds with a new toolbox containing three different welds: (i) welds with optimized penetration, (ii) welds with optimized weld toe, and (iii) welds with a low cost. Right usage of these weld types contributes to an efficient production that offer a long fatigue life. This paper describes a holistic view of the subject and highlights issues with the traditional way of working. The challenge and the novelty in the paper are the connection between the welding process, weld demands, and fatigue life properties. This connection is necessary for the development of welding procedures that can contribute to the fabrication of weight optimized welded structures with a predictable life. © 2015 Springer-Verlag London

  • 5.
    Åstrand, Erik
    University West, Department of Engineering Science, Research Environment Production Technology West.
    Key Changes in the Welding of Fatigue Loaded Structures2014In: Proceedings of the 6th International Swedish Production Symposium 2014 / [ed] Stahre, Johan, Johansson, Björn & Björkman, Mats, 2014, p. 1-7Conference paper (Refereed)
    Abstract [en]

    This paper discusses welding problems of today and the possibilities for tomorrow for companies in the welding industry. By leaving old welding procedures based on traditions and applying new scientifically developed welding demands and procedures there is a vast potential to improve strength performance of the structures and increased competitiveness regarding weld work for the companies. Unfortunately, no changes are done easily and quickly and this paper gives proposals how changes can be done efficiently.

  • 6.
    Åstrand, Erik
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    The Ad Hoc Nature of Weld Quality and Welding Procedures for Fatigue2013In: Design, Fabrication and Economy of Metal Structures: International Conference Proceedings 2013, Miskolc, Hungary, April 24-26, 2013 / [ed] Jármai, Károly, Farkas, József (Eds.), Berlin: Springer, 2013, p. 243-248Conference paper (Refereed)
  • 7.
    Åstrand, Erik
    University West, Department of Engineering Science, Research Environment Production Technology West.
    Weld Procedures and Demands for Improved Fatigue Strength of Single Load Carrying Fillet Welds2013In: Trends in Welding Research: Proceedings of the 9th International Conference / [ed] T. DeRoy, S.A. David, T. Koseki, H. Basdeshia, Chicago: ASM International, 2013, p. 798-804Conference paper (Refereed)
    Abstract [en]

    Traditional weld demands on throat size and leg length does not support a welding process for improved penetration. This paper includes theoretical analysis of welded samples showing the potential with welds that have a prescribed asymmetry. Weld with a larger leg length against the web plate offer in this study improved fatigue properties and could also offer potential for reduced welding time, a smaller amount of filler material and potentially make the quality inspection more relevant. Copyright © 2013 ASM International® All rights reserved.

  • 8.
    Åstrand, Erik
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation Systems.
    Sikström, Fredrik
    University West, Department of Engineering Science, Division of Automation Systems.
    Lindgren, Eric
    Improved fatigue properties of welded box beams by tailored welding procedures for high penetration fillet weldsIn: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024Article in journal (Other academic)
  • 9.
    Åstrand, Erik
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West. Volvo Construction Equipment AB, Braås, Sweden .
    Stenberg, T.
    Royal Institute of Technology (KTH), Department of Aeronautical and Vehicle Engineering, Division of Lightweight Structures, Stockholm, Sweden .
    Jonsson, B.
    Volvo Construction Equipment AB, Braås, Sweden .
    Barsoum, Z.
    Royal Institute of Technology (KTH), Department of Aeronautical and Vehicle Engineering, Division of Lightweight Structures, Stockholm, Sweden .
    Welding procedures for fatigue life improvement of the weld toe2016In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 60, no 3, p. 573-580Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of an experimental study of gas metal arc welded, GMAW, cruciform joints made of common construction steel S355. The hypothesis is that smooth undercuts in as welded conditions can give enhanced fatigue properties similarly as post treated welds. Undercuts are generally seen as a defect or imperfection. Welders try to avoid these and repair them when they occur, which result in increased production lead time. Post weld improvement methods i.e. grinding or high-frequency-impact treatment (HFMI) as fatigue-enhancing post-treatment methods enforce amongst other effects a certain smooth undercut-shaped groove in the treated weld toe region. The obtained shallower weld toe transition reduces the geometrical notch effect and increases fatigue strength. This paper presents a study whereas welded specimens with a weld toe geometry similar to what is obtained by weld toe grinding or HFMI-treatment, has been produced, fatigue tested and analyzed. The improvement of the fatigue strength is comparable to post-weld treated specimens. It has proven to be an efficient way to achieve high-quality welds without introducing any additional operations in production, thus enabling weight reduction using cost-effective methods.

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