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  • 101.
    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)
  • 102.
    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.
    McDill, J.M.J.
    Carleton University, Ottawa.
    Oddy, Alan S.
    Oddy/McDIll Numerical Investigations Sciences, Inc..
    Automatic remeshing for three-dimensional finite element simulation of welding1997In: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, E-ISSN 1879-2138, Vol. 147, no 3-4, p. 401-409Article in journal (Refereed)
    Abstract [en]

    Three-dimensional finite element simulation of electron beam welding of a large copper canister has been performed. The use of an automatic remeshing algorithm, based on a graded hexahedral element was found to be effective. With this algorithm the strongly nonlinear thermomechanical effects locally close to the moving heat source can accurately be modelled using a dense element mesh that follows the heat source.

  • 103.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsson, Mikael
    Accuracy and efficiency in computational plasticity1991In: Proceedings of the International Conference on Mechanics of Solids and Structures: Nanyang Technological University ; 11 - 13 September 1991 / [ed] Daniel T. Lwin; Frank W. Travis, Singapore: World Scientific and Engineering Academy and Society, 1991Conference paper (Refereed)
  • 104.
    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)
  • 105.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Kalhori, Vahid
    Lundblad, Mikael
    Machining simulations and their use in industry2005In: VIII International Conference on Computational Plasticity: COMPLAS VIII / [ed] E. Oñate; D. R. J. Owen, International Center for Numerical Methods in Engineering (CIMNE), 2005, p. 335-338Conference paper (Refereed)
    Abstract [en]

    Machining simulations is a challenge both with respect to demands on robust numerical methods as well as modelling issues. The paper outlines some of the challenges but also current use of simulations at Sandvik Coromant.

    Download full text (pdf)
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  • 106.
    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

  • 107.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Additive manufacturing and high performance applications2018In: Proceedings Of The 3rd International Conference On Progress In Additive Manufacturing (PRO-AM 2018) / [ed] Chua C.K.,Yeong W.Y.,Liu E.,Tan M.J.,Tor S.B., Pro-AM , 2018, p. 214-219Conference paper (Refereed)
    Abstract [en]

    The requirement on life and robustness for aero-engine components poses obstacles to additive manufacturing. It is expected that increasing knowledge about the process and thereby its development together with adaption of existing alloys may improve this state. Simulations can contribute to understanding as well as be used in the design of process and components in order to reduce residual deformations and stresses as well as defects. Models for the latter are still not well established. The paper describes various existing approaches and also on-going developments at Luleå University of Technology that enable better descriptions in the near weld region for crack initiation.

  • 108.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Approaches in computational welding mechanics applied to additive manufacturing: Review and outlook2018In: Comptes rendus. Mecanique, ISSN 1631-0721, E-ISSN 1873-7234, Vol. 346, no 11, p. 1033-1042Article in journal (Refereed)
    Abstract [en]

    The development of computational welding mechanics (CWM) began more than four decades ago. The approach focuses on the region outside the molten pool and is used to simulate the thermo-metallurgical-mechanical behaviour of welded components. It was applied to additive manufacturing (AM) processes when they were known as weld repair and metal deposition. The interest in the CWM approach applied to AM has increased considerably, and there are new challenges in this context regarding welding. The current state and need for developments from the perspective of the authors are summarised in this study.

  • 109.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Edberg, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Svoboda, Ales
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Challenges in finite element simulations of chain of manufacturing processes2013In: Physical and numerical simulation of materials processing VII: selected, peer reviewed papers from the 7th International Conference on Physical and Numerical Simulation of Materials Processing (ICPNS'13), June 16-19, 2013, Oulu, Finland / [ed] L. Pentti Karjalainen; David A. Porter; Seppo A. Järvenpää, Durnten-Zurich: Trans Tech Publications Inc., 2013, p. 349-353Conference paper (Refereed)
    Abstract [en]

    Simulation of some, or all, steps in a manufacturing chain may be important for certain applications in order to determine the final achieved properties of the component. The paper discusses the additional challenges in this context

  • 110.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Fisk, Martin
    Malmö University.
    Thermo-mechanics and microstructure evolution in manufacturing simulations2013In: Journal of thermal stresses, ISSN 0149-5739, E-ISSN 1521-074X, Vol. 36, no 6, p. 564-588Article in journal (Refereed)
    Abstract [en]

    Thermal stresses and deformations are present and important for many manufacturing processes. Their effect depends strongly on the material behavior. The finite element method has been applied successfully for manufacturing simulations. There are numerical challenges in some cases due to large deformations, strong non-linearities etc. However, the most challenging aspect is the modeling of the material behavior. This requires in many cases coupled constitutive and microstructure models.

  • 111.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Fisk, Martin
    Malmö University, Malmö, Sweden.
    Draxler, Joar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modelling additive manufacturing of superalloys2019In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 35, p. 252-258Article in journal (Refereed)
    Abstract [en]

    There exist several variants of Additive Manufacturing (AM) applicable for metals and alloys. The two main groups are Directed Energy Deposition (DED) and Powder Bed Fusion (PBF). AM has advantages and disadvantages when compared to more traditional manufacturing methods. The best candidate products are those with complex shape and small series and particularly individualized product. Repair welding is often individualized as defects may occur at various instances in a component. This method was used before it became categorized as AM and in most cases, it is a DED process. PBF processes are more useful for smaller items and can give a finer surface. Both DED and PBF products require subsequent surface finishing for high performance components and sometimes there is also a need for post heat treatment. Modelling of AM as well as eventual post-processes can be of use in order to improve product quality, reducing costs and material waste. The paper describes the use of the finite element method to simulate these processes with focus on superalloys.

  • 112.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Fisk, Martin
    Materials Science and Applied Mathematics, Faculty of Technology and Society, Malmö University, Malmö University, Materials Science, Technology and Society, Malmö Högskola.
    Pederson, Robert
    Volvo Aero Corporation, Trollhättan, GKN Aerospace Engine Systems, Trollhättan.
    Andersson, Joel
    GKN Aerospace Engine Systems, Trollhättan, LKAB.
    Simulation of additive manufacturing using coupled constitutive and microstructure models2016In: Additive Manufacturing, ISSN 2214-8604, Vol. 12 B, p. 144-158Article in journal (Refereed)
    Abstract [en]

    The paper describes the application of modeling approaches used in Computational Welding Mechanics (CWM) applicable for simulating Additive Manufacturing (AM). It focuses on the approximation of the behavior in the process zone and the behavior of the solid material, particularly in the context of changing microstructure. Two examples are shown, one for the precipitation hardening Alloy 718 and one for Ti-6Al-4V. The latter alloy is subject to phase changes due to the thermal cycling.

  • 113.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Malmelöv, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Thermal stresses and computational welding mechanics2019In: Journal of thermal stresses, ISSN 0149-5739, E-ISSN 1521-074X, Vol. 42, no 1, p. 107-121Article in journal (Refereed)
    Abstract [en]

    Computational welding mechanics (CWM) have a strong connection to thermal stresses, as they are one of the main issues causing problems in welding. The other issue is the related welding deformations together with existing microstructure. The paper summarizes the important models related to prediction of thermal stresses and the evolution of CWM models in order to manage the large amount of ‘welds’ in additive manufacturing.

  • 114.
    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.

  • 115.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Oddy, A.
    Toolbox for computing phase and material properties of hypoeutecoid steels in Satoh test1995In: Thermal stresses '95: proceedings of the First International Symposium on Thermal Stresses and Related Topics, June 5 - 7, 1995, Shizoka University, Shizuoka University , 1995, p. 517-525Conference paper (Refereed)
  • 116.
    Lindgren, Lars-Erik
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Carlsson, Per
    Dalarna University, School of Technology and Business Studies, Material Science.
    Simulation of hydroforming of steel tube made of metastable stainless steel2010In: International journal of plasticity, ISSN 0749-6419, E-ISSN 1879-2154, Vol. 26, no 11, p. 1576-1590Article in journal (Refereed)
    Abstract [en]

    The Olson-Cohen model for strain-induced deformation, further developed by Stringfellow and others, has been calibrated together with a flow stress model for the plastic deformation of metastable stainless steel. Special validation tests for checking one of the limitations of the model have also been carried out. The model has been implemented into a commercial finite element code using a staggered approach for integrating the stress-strain relations with the microstructure model. Results from a thermo-mechanical coupled simulation of hydroforming of a tube have been compared with corresponding experiments. The agreement between experimental results of radial expansion and martensite fraction and the corresponding computed results is good. 

  • 117.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Olsson, Mikael
    Dalarna University.
    Carlsson, Per
    Dalarna University.
    Simulation of hydroforming of steel tube made of metastable stainless steel2010In: International journal of plasticity, ISSN 0749-6419, E-ISSN 1879-2154, Vol. 26, no 11, p. 1576-1590Article in journal (Refereed)
    Abstract [en]

    The Olson-Cohen model for strain induced deformation, further developed by Stringfellow and others, has been calibrated together with a flow stress model for the plastic deformation of metastable stainless steel. Special validation tests for checking one of the limitations of the model have also been carried out. The model has been implemented into a commercial finite element code using a staggered approach for integrating the stress-strain relations with the microstructure model. Results from a thermo-mechanical coupled simulation of hydroforming of a tube have been compared with corresponding experiments. The agreement between experimental results of radial expansion and martensite fraction and the corresponding computed results is good.

  • 118.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Qin, Hao
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Liu, Wing Kam
    Northwestern University.
    Tang, Shan
    Northwestern University.
    Simplified multiscale resolution theory for elastic material with damage2011In: Computational plasticity XI : fundamentals and applications: proceedings of the XI International Conference on Computational Plasticity - fundamentals and applications held in Barcelona, Spain, 07 - 09 September 2011, Barcelona: CINME , 2011, p. 576-586Conference paper (Refereed)
    Abstract [en]

    The multiscale resolution continuum theory (MRCT) is a higher order continuum mechanics. A particle is represented by a point that is deformable. This enables the possibility to include the effect of microstructure features in the continuum model on the deformation behavior through additional nodal variables for the higher order scale. This reduces the need for a very fine mesh in order to resolve microstructure details. It is possible to further reduce the computational effort by keeping the additional degree of freedoms to a minimum by tailoring the theory to specific phenomena. The latter is illustrated in a simplified context for an elastic material with damage.

  • 119.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Qin, Hao
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Wedberg, Dan
    AB Sandvik Coromant, Metal Cutting Modeling, 811 81 Sandviken.
    Improved and simplified dislocation density based plasticity model for AISI 316 L2017In: Mechanics of materials (Print), ISSN 0167-6636, E-ISSN 1872-7743, Vol. 108, p. 68-76Article in journal (Refereed)
    Abstract [en]

    A previously published dislocation density based flow stress model has been refined and made more consistent with underlying physical assumptions. The previous model included many temperature dependent parameters that are taken as constant in the current work. The model has also been simplified with respect to dynamic strain aging. Additional contributions to flow stress from the Hall-Petch effect and solute hardening have now been explicitly included in the model. Furthermore, the dynamic recovery part of the model has been improved.

  • 120.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Runesson, Kenneth
    Luleå tekniska universitet.
    Skyttebol, Anders
    Luleå tekniska universitet.
    Nonlinear finite element analysis and application to welded structures2003In: Comprehensive structural integrity: [fracture of materials from nano to macro]. Numerical and computational methods, Amsterdam: Elsevier, 2003, p. 257-320Chapter in book (Other academic)
  • 121.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Runnemalm, Henrik
    Luleå tekniska universitet.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Simulation of multipass welding of a thick plate1999In: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 44, no 9, p. 1301-1316Article in journal (Refereed)
    Abstract [en]

    Multipass butt welding of a very thick steel plate has been performed. Transient temperatures and residual stresses have been measured. The agreement between calculations and experiments is good. Two different approaches, quiet and inactive elements, for modelling multipass welding are compared. The first approach is straightforward to apply in most finite element codes. The inactive element method requires a code that can regenerate the finite element model automatically or otherwise very tedious manual work is necessary as the elements are added to the model when welds are laid. It is shown that both techniques give the same results but the computational effort is reduced by using inactive elements. It also circumvents the problem in the quiet element approach of choosing properties of elements in the model that represent the case when welds are not laid.

  • 122.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Svoboda, Ales
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Wedberg, Dan
    AB Sandvik Coromant, Metal Cutting Research, Sandviken.
    Lundblad, Mikael
    AB Sandvik Coromant, Metal Cutting Research, Sandviken.
    Towards predictive simulations of machining2016In: Comptes rendus. Mecanique, ISSN 1631-0721, E-ISSN 1873-7234, Vol. 344, no 4-5, p. 284-295Article in journal (Refereed)
    Abstract [en]

    Machining simulations are challenging with respect to both numerical issues and physical phenomena occurring during machining. The latter are mainly related to the description of the bulk material behaviour (plasticity) and surface properties (friction and wear). The aim of this paper is to present what is required for predictive models, depending on their scopes, as well as the needed developments for the future. The paper includes a short review of selected works that are relevant for this purpose as well as conclusions based on our own experience

  • 123.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Wedberg, Dan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Material modelling and physical based models with particular emphasis on high strain rates2009In: International Symposium on Plasticity 2009 / [ed] Akhtar Khan, 2009Conference paper (Other academic)
    Abstract [en]

    The problem of calibrating material models with tests in a limited range of conditions and then applying outside this range is discussed. This is the case when machining simulations are performed where very high strain rates (>50000s-1) can be obtained. The paper discusses the Johnson-Cook model, an empirical model that is common for high strain rate applications and a physical based dislocation density model. Test data for AISI 316L ranging from 0.001 to 10s-1 and room temperature up to 1300°C are used for calibration of the models and thereafter additional tests up to 9000s-1 at varying initial temperatures are compared with the model predictions

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    FULLTEXT01
  • 124.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Wedberg, Dan
    Svoboda, Ales
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Verification and validation of machining simulations for sufficient accuracy2009In: Computational Plasticity X: fundamentals and applications ; proceedings of the X International Conference on Computational Plasticity - fundamentals and applications held in Barcelona, Spain, 02 - 04 September 2009 / [ed] E. Onate, International Center for Numerical Methods in Engineering (CIMNE), 2009Conference paper (Refereed)
  • 125.
    Lindgren, Michael
    et al.
    Dalarna University.
    Edberg, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Roll Forming2014In: Handbook of Manufacturing Engineering and Technology, London: Encyclopedia of Global Archaeology/Springer Verlag, 2014, p. 1-19Chapter in book (Refereed)
    Abstract [en]

    Roll forming is cost-effective compared to other sheet metal forming processes for uniform profiles. The process has during the last 10 years developed into forming of profiles with varying cross sections and is thereby becoming more flexible. The motion of the rolls can now be controlled with respect to many axes enabling a large variation in the profiles along the formed sheet, the so-called 3D roll forming or flexible roll forming technology. The roll forming process has also advantages compared to conventional forming for high-strength materials. Furthermore, computer tools supporting the design of the process have also been developed during the last 10 years. This is quite important when designing the forming of complex profiles. The chapter describes the roll forming process, particularly from the designer’s perspective. It gives the basic understanding of the process and how it is designed. Furthermore, modern computer design and simulation tools are discussed.

  • 126.
    Lindgren, Michael
    et al.
    Dalarna University.
    Edberg, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Roll Forming2015In: Handbook of Manufacturing Engineering and Technology, London: Encyclopedia of Global Archaeology/Springer Verlag, 2015, p. 285-307Chapter in book (Refereed)
    Abstract [en]

    Roll forming is cost-effective compared to other sheet metal forming processes for uniform profiles. The process has during the last 10 years developed into forming of profiles with varying cross sections and is thereby becoming more flexible. The motion of the rolls can now be controlled with respect to many axes enabling a large variation in the profiles along the formed sheet, the so-called 3D roll forming or flexible roll forming technology. The roll forming process has also advantages compared to conventional forming for high-strength materials. Furthermore, computer tools supporting the design of the process have also been developed during the last 10 years. This is quite important when designing the forming of complex profiles. The chapter describes the roll forming process, particularly from the designer’s perspective. It gives the basic understanding of the process and how it is designed. Furthermore, modern computer design and simulation tools are discussed

  • 127.
    Lindwall, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Thermal FE-simulation of PBF using adaptive meshing and time stepping2017In: Simulation for Additive Manufacturing 2017, Sinam 2017, Technische Universität München (TUM), ECCOMAS, , 2017, p. 62-63Conference paper (Refereed)
  • 128.
    Lindwall, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Malmelöv, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Efficiency and Accuracy in Thermal Simulation of Powder Bed Fusion of Bulk Metallic Glass2018In: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 70, no 8, p. 1598-1603Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing by powder bed fusion processes can be utilized to create bulk metallic glass as the process yields considerably high cooling rates. However, there is a risk that reheated material set in layers may become devitrified, i.e., crystallize. Therefore, it is advantageous to simulate the process to fully comprehend it and design it to avoid the aforementioned risk. However, a detailed simulation is computationally demanding. It is necessary to increase the computational speed while maintaining accuracy of the computed temperature field in critical regions. The current study evaluates a few approaches based on temporal reduction to achieve this. It is found that the evaluated approaches save a lot of time and accurately predict the temperature history.

  • 129.
    Lindwall, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pacheco, Victor
    Ångström Laboratory, Uppsala University, Uppsala.
    Sahlberg, Martin
    Ångström Laboratory, Uppsala University, Uppsala.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Thermal simulation and phase modeling of bulk metallic glass in the powder bed fusion process2019In: Additive Manufacturing, ISSN 2214-8604, Vol. 27, p. 345-352Article in journal (Refereed)
    Abstract [en]

    One of the major challenges with the powder bed fusion process (PBF) and formation of bulk metallic glass (BMG) is the development of process parameters for a stable process and a defect-free component. The focus of this study is to predict formation of a crystalline phase in the glass forming alloy AMZ4 during PBF. The approach combines a thermal finite element model for prediction of the temperature field and a phase model for prediction of crystallization and devitrification. The challenge to simulate the complexity of the heat source has been addressed by utilizing temporal reduction in a layer-by-layer fashion by a simplified heat source model. The heat source model considers the laser power, penetration depth and hatch spacing and is represented by a volumetric heat density equation in one dimension. The phase model is developed and calibrated to DSC measurements at varying heating rates. It can predict the formation of crystalline phase during the non-isothermal process. Results indicate that a critical location for devitrification is located a few layers beneath the top surface. The peak is four layers down where the crystalline volume fraction reaches 4.8% when 50 layers are built.

  • 130.
    Liu, J.
    et al.
    Nanyang Technological University.
    Edberg, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Tan, M.J.
    Nanyang Technological University.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Castagne, S.
    Nanyang Technological University.
    Jarfors, A.E.W.
    Jönköping University.
    Finite element modelling of superplastic-like forming using a dislocation density-based model for AA50832013In: Modelling and Simulation in Materials Science and Engineering, ISSN 0965-0393, E-ISSN 1361-651X, Vol. 21, no 2, p. 25006-Article in journal (Refereed)
    Abstract [en]

    Superplastic-like forming is a newly improved sheet forming process that combines the mechanical pre-forming (also called hot drawing) with gas-driven blow forming (gas forming). Non-superplastic grade aluminium alloy 5083 (AA5083) was successfully formed using this process. In this paper, a physical-based material model with dislocation density and vacancy concentration as intrinsic foundations was employed. The model describes the overall flow stress evolution of AA5083 from ambient temperature up to 550 °C and strain rates from 10−4 up to 10−1 s−1. Experimental data in the form of stress–strain curves were used for the calibration of the model. The calibrated material model was implemented into simulation to model the macroscopic forming process. Hereby, finite element modelling (FEM) was used to estimate the optimum strain-rate forming path, and experiments were used to validate the model. In addition, the strain-rate controlled forming was conducted for the purpose of maintaining the gas forming with an average strain rate of 2 × 10−3 s−1. The predicted necking areas closely approximate the localized thinning observed in the part. Strain rate gradients as a result of geometric effects were considered to be the main reason accounting for thinning and plastic straining, which were demonstrated during hot drawing and gas forming by simulations.

  • 131.
    Liu, Wing Kam
    et al.
    Northwestern University, Department of Mechanical Engineering, Evanston, IL.
    Siad, Larbi
    University of Reims.
    Tian, Rong
    Northwestern University, Department of Mechanical Engineering, Evanston, IL.
    Lee, Sanghoon
    Northwestern University, Department of Mechanical Engineering, Evanston, IL.
    Lee, Dockjin
    Sungkyunkwan University, School of Mechanical Engineering, Suwon.
    Yin, Xiaolei
    Northwestern University, Department of Mechanical Engineering, Evanston, IL.
    Chen, Wei
    Northwestern University, Department of Mechanical Engineering, Evanston, IL.
    Chan, Stephanie
    Northwestern University, Department of Material Science, Evanston, IL.
    Olson, Gregory B.
    Northwestern University, Department of Material Science, Evanston, IL.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Horstemeyer, Mark F.
    Mississippi State University, Department of Mechanical Engineering.
    Chang, Yoon-Suk
    Sungkyunkwan University, School of Mechanical Engineering, Suwon.
    Choi, Jae-Boong
    Sungkyunkwan University, School of Mechanical Engineering, Suwon.
    Kim, Young Jin
    Sungkyunkwan University, School of Mechanical Engineering, Suwon.
    Complexity science of multiscale materials via stochastic computations2009In: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 80, no 6-7, p. 932-978Article in journal (Refereed)
    Abstract [en]

    New technological advances today allow for a range of advanced composite materials, including multilayer materials and nanofiber-matrix composites. In this context, the key to developing advanced materials IS file understanding of the interplay between the various physical scales present. from the atomic level Interactions to the microstructaral composition and the marcoscale behavior Using the developing 'multiresolution data sets mechanics' the 'predictive science-based governing laws of the materials microstructure evolutions' are derived and Melted into a 'stochastic multiresolution design framework' Under such a framework. the governing laws Of the materials microstructure evolution will be essential to assess, across multiple scales. The impact of multiscale material design. geometry design of a structure and the manufacturing process conditions, by following the cause-effect relationship from structure property and then to performance The future Integrated multiscale analysis system will be Constructed based on a probabilistic complexity science-based mathematical framework. its verification, validation and uncertainty quantification tire done through carefully designed experiments, and file life-cycled materials design for products design and manufacturing is performed through the use of petascale computing. The various techniques of microstructure reconstruction result in the genetation of model microstructures that, at some level, has the same statistical properties as the real heterogenous media. Having reconstructed the heterogeneous medium. one can then evaluate Its effective properties via direct numerical simulation and compare these values with experimentally measured properties of the actual medium. The proposed analysis will be dynamic in nature to capture the multi-stage historical evolvement of material/structure performance over the life span of a product. In addition to providing more accurate assessment of structure performance with stochastic multiscale analysis. our development will provide the capability of predicting failures and system reliability to enable more reliable design and decisions in product development.

  • 132.
    Lundbäck, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Fisk, Martin
    Materials Science and Applied Mathematics, Faculty of Technology and Society, Malmö University, Malmö University, Materials Science, Technology and Society, Malmö Högskola.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modelling of stresses, deformations and microstructure evolution during additive manufacturing2017In: Simulation for Additive Manufacturing 2017, Sinam 2017, International Center for Numerical Methods in Engineering (CIMNE), 2017, p. 48-Conference paper (Refereed)
  • 133.
    Lundbäck, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Finite Element Simulation to Support Sustainable Production by Additive Manufacturing2016In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 7, p. 127-130Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing (AM) has been identified as a disruptive manufacturing process having the potential to provide a number of sustainability advantages. Functional products with high added value and a high degree of customization can be produced. AM is particularly suited for industries in which mass customization, light weighting of parts and shortening of the supply chain are valuable. Its applications can typically be found in fields such as the medical, dental, and aerospace industries. One of the advantages with AM is that little or no scrap is generated during the process. The additive nature of the process is less wasteful than traditional subtractive methods of production. The capability to optimize the geometry to create lightweight components can reduce the material use in manufacturing. One of the challenges is for designers to start using the power of AM. To support the designers and manufacturing, there is a need for computational models to predicting the final shape, deformations and residual stresses. This paper summarizes the advantages of AM in a sustainability perspective. Some examples of application of simulation models for AM are also given.

  • 134.
    Lundbäck, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modelling of metal deposition2011In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 47, no 10, p. 1169-1177Article in journal (Refereed)
    Abstract [en]

    Modelling and simulation of metal deposition (MD) poses several challenges to the modeller in addition to the usual challenges in modelling of welding. The aim of the work presented in this paper is to enable simulation of metal deposition for large three-dimensional components. Weld paths that are created in an off-line programming system (OLP) can be used directly to prescribe the movement of the heat source in the model. The addition of filler material is done by activation of elements. Special care must be taken to the positioning of the elements, due to large deformations. Nodes are moved to ensure that the added material has correct volume and shape. A physically based material model is also implemented. This material model is able to describe the material behaviour over a large strain, strain rate and temperature range. Temperature measurements and deformation measurements are done in order to validate the model. The computed thermal history is in very good agreement with measurements. The computed and measured deformations also show quite good agreement. It has been shown that the approach yields correct results, providing that flow stress and heat input models are calibrated with sufficient accuracy. The method reduces the modelling work considerably for metal deposition and multipass welding. It can be used for detailed models but also lumping of welds is possible and often necessary for industrial applications.

  • 135.
    Lundbäck, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Babu, Bijish
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Charles, Corinne
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Simulating a chain of manufacturing processes for prediction of component properties2011In: XXth International Symposium on Air Breathing Engines 2011: (ISABE 2011) : Gothenburg, Sweden 12-16 Swptember 2011, Red Hook, NY: Curran Associates, Inc., 2011Conference paper (Refereed)
    Abstract [en]

    An integrated design of material and process is necessary when designing a component where the effect of the manufacturing route on its performance must be accounted for. This is particularly the case for welded components even when post weld heat treatment is performed. The paper describes developments done at Luleå University of Technology in cooperation with Volvo Aero in the Swedish National Programme for Aeronautical Research (NFFP) and in different European projects. The paper focuses on two particular issues of importance. The first is of more administrative character, the transfer of data between different finite element models used in each of the manufacturing steps. The other aspect is the extremely important issue of material modeling.Material models for simulation of a chain of manufacturing processes include additional complications besides large variations in strain rates and temperatures. These complications are caused by the changing microstructure that may occur. The authors expect that physically based models can have a larger range of applicability than engineering type of models. Physical based models are formulated by considering the underlying physics of the deformation whereas engineering type of models are more of a curve-fitting nature. The physical based models may also have a natural coupling to models of the microstructure evolution. However, the models must still be tractable for large-scale computations. Thus, they should be of the internal state variable type with relatively few additional parameters and equations to solve at the integration point level of finite elements. The paper describes a basic dislocation density model used in modelling different manufacturing processes and how it can be coupled to microstructure models. It is based on dislocation glide as the dominating mechanism for the plastic deformation. This may be models for phase changes, like in Ti6-4, or precipitate growth/dissolution as in Alloy 718. The coupled models will not only make it possible to describe the material behavior more correct over the process cycles but also predict the obtained microstructure. It is expected that future research may couple this information with defect predictions in order to contribute to life assessment. The paper includes some example of manufacturing simulations and also an example of simulation of a chain of manufacturing processes.

  • 136.
    Lundbäck, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pederson, Robert
    Hörnqvist Colliander, Magnus
    GKN Aerospace Engine Systems, 461 81 Trollhättan.
    Brice, Craig
    NASA Langley Research Center, Hampton, Virginia USA.
    Steuwer, Axel
    NMMU, Gardham Av, 6031 Port Elizabeth, South Africa.
    Heralic, Almir
    GKN Aerospace Engine Systems, 461 81 Trollhättan.
    Buslaps, Thomas
    ID15A, European Synchrotron Radiation Facility ESRF, Grenoble, France.
    Lindgren, Lars-Erik
    Modeling and Experimental Measurement with Synchrotron Radiation of Residual Stresses in Laser Metal Deposited Ti-6Al-4V2016In: Proceedings of the 13th World Conference on Titanium, 2016, p. 1279-1282Conference paper (Refereed)
    Abstract [en]

    There are many challenges in producing aerospace components by additive manufacturing (AM). One of them is to keep the residual stresses and deformations to a minimum. Another one is to achieve the desired material properties in the final component. A computer model can be of great assistance when trying to reduce the negative effects of the manufacturing process. In this work a finite element model is used to predict the thermo-mechanical response during the AM-process. This work features a physically based plasticity model coupled with a microstructure evolution model for the titanium alloy Ti -6Al-4V. Residual stresses in AM components were measured non-destructively using high-energy synchrotron X-ray diffraction on beam line ID15A at the ESRF, Grenoble. The results are compared with FE model predictions of residual stresses. During the process, temperatures and deformations was continuously measured. The measured and computed thermal history agrees well. The result with respect to the deformations agrees well qualitatively. Meaning that the change in deformation in each sequence is well predicted but there is a systematic error that is summing so that the quantitative agreement is lost.

  • 137.
    Lundbäck, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pederson, Robert
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hörnqvist, Magnus
    GKN Aerospace Engine Systems.
    Brice, Craig
    NASA Langley Research Center, Hampton.
    Steuwer, Axel
    MAX-lab, Lund University.
    Heralic, Almir
    GKN Aerospace Engine Systems Sweden.
    Buslaps, Thomas
    ID15A, European Synchrotron Radiation Facility ESRF, 38042 Grenoble.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modelling and Simulation of Metal Deposition on a Ti-6al-4v Plate2015Conference paper (Other academic)
    Abstract [en]

    There are many challenges in producing aerospace components by metal deposition (MD). One of them is to keep the residual stresses and deformations to a minimum. Anotherone is to achieve the desired material properties in the final component. A computer model can be of great assistance when trying to reduce the negative effects of the manufacturing process. In this work a finite element model is used to predict the thermo-mechanical response during the MD-process. This work features a pysically based plasticity model coupled with a microstructure evolution model for the titanium alloy Ti-6Al-4V. A thermally driven microstructure model is used to derive the evolution of the non-equilibrium compositions of α-phases and β-phase. Addition of material is done by activation of elements. The method is taking large deformations into consideration and adjusts the shape and position of the activated elements. This is particularilly important when adding material onto thin and flexible structures. The FE-model can be used to evaluate the effect of different welding sequenses. Validation of the model is performed by comparing measured deformations, strains, residual stresses and temperatures with the computed result. The deformations, strains and temepratures are measured during the process. The deformations are measured with a LVDT-gauge at one location. The strains are measured with a strain gauge at the same location as the deformations. The temperature is measured at five locations, close to the weld and with an increasing distance of one millimeter between each thermo couple. The residual stresses in MD component were measured non-destructively using high-energy synchrotron X-ray diffraction on beam line ID15A at the ESRF, Grenoble.

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  • 138.
    Malmelöv, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Fisk, Martin
    Materials Science and Applied Mathematics, Malmö University, 205 06 Malmö, Sweden.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Simulation of additive manufacturing of alloy 625 with a physically based material model2019Conference paper (Other academic)
  • 139.
    Malmelöv, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    History Reduction by Lumping for Time-Efficient Simulation of Additive Manufacturing2020In: Metals, ISSN 2075-4701, Vol. 10, no 1, article id 58Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing is the process by which material is added layer by layer. In most cases, many layers are added, and the passes are lengthy relative to their thicknesses and widths. This makes finite element simulations of the process computationally demanding owing to the short time steps and large number of elements. The classical lumping approach in computational welding mechanics, popular in the 80s, is therefore, of renewed interest and is evaluated in this work. The method of lumping means that welds are merged. This allows fewer time steps and a coarser mesh. It was found that the computation time can be reduced considerably, with retained accuracy for the resulting temperatures and deformations. The residual stresses become, to a certain degree, smaller. The simulations were validated against a directed energy deposition (DED) experiment with alloy 625.

  • 140.
    Malmelöv, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Validation of an approach to reduce simulation time for additive manufacturing2017In: Simulation for Additive Manufacturing 2017, Sinam 2017, Technische Universität München (TUM), ECCOMAS , 2017, p. 64-65Conference paper (Refereed)
  • 141. McDill, J. Moyra J.
    et al.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Reed, Roger C.
    Oddy, Alan S.
    Continuous improvement in thermal-mechanical finite element analysis2000In: International conference on processing and manufacturing of advanced materials: processing, fabrication, properties, applications, THERMEC 2000 / [ed] T. Chandra, Elsevier, 2000Conference paper (Refereed)
  • 142.
    Molin, Nils-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Holmgren, Mats
    Luleå tekniska universitet.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jansson, Erik
    Department of Speech Communication and Music Acoustics, KTH.
    Eigenmodes of av violin body1990In: Proceedings / Nordic Acoustical Meeting 90 - NAM 90: 11-13, 1990 Luleå, Sweden / [ed] Ulrik Sundbäck, Luleå: CENTEK , 1990, p. 421-428Conference paper (Refereed)
  • 143.
    Molin, Nils-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jansson, Erik V.
    Royal Institute of Technology.
    Parameters of violin plates and their influence on the plate modes1988In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 83, no 1, p. 281-291Article in journal (Refereed)
    Abstract [en]

    Noncontact measuring methods and numerical calculations are used in a study of musical instruments. First, a simple method to determine the material parameters of a blank to a violin plate is presented. Eigenmodes of rectangular free-free violin wooden blanks are determined using optical nondestructive methods, Chladni patterns, or tapping. Assuming orthotropic material, the first three eigenmodes for such a blank are calculated using the finite element method (FEM). It is shown that the frequency of each eigenmode depends on separate elastic parameters. With this one variable dependence, it is a simple task to determine effective material parameters for quarter-cut standard wooden blanks when the frequencies and mass are known. Second, the violin maker's problem with the influence of material and geometrical parameters on the vibration modes is investigated. Numerical models and corresponding real violin plates are made from the spruce and the maple blanks. Good agreement between calculated and experimentally obtained plate modes is found. Calculations with a 10% variation in each parameter are thereafter used to give information about the influence of overall plate thickness variation, of local thickness variations, of changes in arch-height, and of material parameters. Third, boundary conditions for the plates when glued to the ribs are examined in a pilot experiment.

  • 144.
    Murgau, C Charles
    et al.
    University West, Trollhättan.
    Pederson, Robert
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    A model for Ti–6Al–4V microstructure evolution for arbitrary temperature changes2012In: Modelling and Simulation in Materials Science and Engineering, ISSN 0965-0393, E-ISSN 1361-651X, Vol. 20, no 5, article id 055006Article in journal (Refereed)
    Abstract [en]

    This paper presents a microstructure model for the titanium alloy Ti–6Al–4V designed to be used in coupled thermo-metallurgical-mechanical simulations of, e.g., welding processes. The microstructure evolution is increasingly taken into consideration in analyses of manufacturing processes since it directly affects the mechanical properties. Thermally driven phase evolutions are accounted for in the model. A state variable approach is adopted to represent the microstructure with the objective to integrate the microstructure changes with a thermo-mechanical model of manufacturing process simulation such as welding. The model is calibrated using the literature data and also validated against a cyclic temperature history during multi-pass welding.

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  • 145.
    Näsström, Mats
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lundström, Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Karlberg, Magnus
    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.
    Turesson, Lena
    Luleå University of Technology, Professional Support, VSS TVM.
    Palmblad, Marie-Louise
    Luleå University of Technology, Professional Support, VSS TVM.
    Projekt: Fastelaboratoriet - VINNEXC2007Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Fastelaboratoriet är ett VINN Excellence Center för innovation inom Funktionella Produkter. Centret skapades till minne av innovatören Rolf Faste som under många år var verksam vid Stanford University i Kalifornien, USA

  • 146.
    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

  • 147.
    Olaogun, O
    et al.
    Department of Mechanical Engineering Science University of Johannesburg, Johannesburg, South Africa;Department of Mechanical Engineering, Kwara State University, Malete, Nigeria.
    Edberg, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Oluwole, O. O.
    Department of Mechanical Engineering, University of Ibadan, Ibadan, Nigeria.
    Akinlabi, E.T
    Department of Mechanical Engineering Science, University of Johannesburg, Johannesburg, South Africa.
    Heat transfer in cold rolling process of AA8015 alloy: a case study of 2-D FE simulation of coupled thermo-mechanical modeling2019In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 100, no 9-12, p. 2617-2627Article in journal (Refereed)
    Abstract [en]

    The finite element method (FEM) is one of the most applicable mathematical analytic methods of rolling processes and is also an efficient method for analyzing coupled heat transfer. Thermal analysis of cold rolling process is not frequently used due to the widespread assumption of insignificant impact during rolling process. This research focuses on the development of coupled thermo-mechanical 2-D FE model analysis approach to study the thermal influence and varying coefficient of friction during the industrial cold rolling process of AA8015 aluminum alloy. Both deformable-rigid and deformable-deformable rigid contact algorithms were examined in the 2-D FE model. Findings revealed that temperature distribution in the roll bite rises steadily in a stepwise manner. The deformable-deformable contact algorithm is the best investigations of thermal behavior of the rolled metal and work rolls necessary for typical application in work roll design. The predicted roll separating force is validated with industrial measurements.

  • 148.
    Olofsson, Kenneth
    et al.
    Luleå tekniska universitet.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Holographic interferometry measurements of transient bending waves in tubes and rings1993In: Experimental mechanics, ISSN 0014-4851, E-ISSN 1741-2765, Vol. 33, no 4, p. 308-313Article in journal (Refereed)
    Abstract [en]

    Propagation bending waves are studied in a tube of steel and in a ring of aluminum. The waves are generated by the impact of a ballistic pendulum. Holographic interferometry, with a double-pulsed ruby laser as light source, is used to record the waves. A conical mirror is placed axially inside the tube. Axial illumination and axial observation directions, make it possible to view all sides of the tube simultaneously with a high sensitivity to radial deformation. The interferograms, which have an unusual perspective, are captured with a CCD-camera and then spatially transformed into an unwrapped strip of the tube wall. This makes the interpretation of the measurements simpler. The geometry of the tube causes the wave pattern to propagate with different speed and amplitude along and across the tube, even when the material itself is isotropic. A finite-element simulation of the impact is compared to the corresponding experiment. An impact on a ring with a defect is performed in order to study the effect on the wave pattern. The proposed method could be used in nondestructive testing of pipes.

  • 149. Ong, J.H.
    et al.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lim, C.S.
    A hidden line algorithm for finite element preprocessor1988In: Proceedings of ICONCG 88 International Conference on Computer Graphics 1988 : 15-16 September 1988 at Hyatt Regency Hotel, Singapore, School of Electrical , 1988, p. 499-510Conference paper (Refereed)
  • 150.
    Qin, Hao
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    MRCT Element With A Dislocation Based Plasticity Model2015In: Computational Plasticity XIII: Fundamentals and Applications - Proceedings of the 13th International Conference on Computational Plasticity - Fundamentals and Applications,held in Barcelona, Spain, 1-3 September 2015 / [ed] E. Oñate; D.R.J. Owen; D. Peric; M. Chiumenti, Barcelona: International Center for Numerical Methods in Engineering (CIMNE), 2015, p. 366-377Conference paper (Refereed)
    Abstract [en]

    The multiresolution continuum theory (MRCT) [1] has been established to link the material's macroscopic behaviour with its microstructural inhomogeneities. Additional kinematic variables in addition to the conventional macroscopic displacement field are added to account for microstructural deformations at multiple microscales. Metal plasticity is associated with interaction of motion of dislocations and microstructures. A Dislocation density based material model [2] calibrated and validated for AISI 316L at different temperatures and strain rates is used as the macroscopic constitutive equation of the MRCT element. We investigated particularly how the changing property of the microdomain with changing temperature affects the macroscopic behaviours of the material

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