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  • 1.
    Babu, Bijish
    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.
    Dislocation density based constitutive model for Ti-6Al-4V used in simulation of metal deposition2007In: Svenska Mekanikdagar 2007: Program och abstracts / [ed] Niklas Davidsson; Elianne Wassvik, Luleå: Luleå tekniska universitet, 2007, p. 84-Conference paper (Other academic)
  • 2. Babu, Bijish
    et al.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Physically based constitutive model for Ti-6Al-4V used in the simulation of manufacturing chain2009In: 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; D.R.J. Owen; B. Suarez, International Center for Numerical Methods in Engineering (CIMNE), 2009Conference paper (Refereed)
    Abstract [en]

    Simulations of manufacturing process chain involving forming, welding and heat treatment are complex because of the varying length and time scales and the range of temperatures which trigger the different associated deformation mechanisms. This paper demonstrates the use of a physically based constitutive model in simulation of a manufacturing chain.

  • 3.
    Babu, Bijish
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials. Swerea MEFOS.
    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.
    Simulation of additive manufacturing of Ti-6Al-4V using a coupled physics-based flow stress and microstructure modelManuscript (preprint) (Other academic)
    Abstract [en]

    Simulating the additive manufacturing process of Ti-6Al-4V is very complex owing to the microstructural changes and allotropic transformation occurring during its thermo-mechanical processing. The alpha-phase with a hexagonal close pack structure is present in three different forms; Widmanstatten, grain boundary, and Martensite. A metallurgical model that computes the formation and dissolution of each of these phases is used in this work. Furthermore, a physically based flow-stress model coupled with the metallurgical model is applied in the simulation of direct energy deposition additive manufacturing case.

  • 4.
    Barsoum, Z.
    et al.
    Kungliga tekniska högskolan, KTH.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Simplified FE welding simulation of fillet welds: 3D effects on the formation residual stresses2009In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 16, no 7, p. 2281-2289Article in journal (Refereed)
    Abstract [en]

    In this study two- and three-dimensional finite element welding simulations have been carried out. The welded component studied is a T-type fillet weld which is frequently used in the heavy vehicle machine industry with plate thicknesses of eight and 20 mm, respectively. The software's used for the welding simulations is MSC.Marc and ANSYS. The objective is to study the formation of the residual stresses due to 3D effect of the welding process. Moreover, welding simulations using solid models and contact models in the un-fused weld roots were carried out in order to investigate the possible effect with respect to the residual stresses. Residual stress measurements were carried out using X-ray diffraction technique on the manufactured T-welded structure. The 2D residual stress predictions shows good agreement with measurements, hence the 2D welding simulation procedure is suitable for residual stress predictions for incorporation in further fatigue crack growth analysis from weld defects emanating from the weld toe and the un-fused root.

  • 5. Berglund, Daniel
    et al.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lundbäck, Andreas
    Three-dimensional finite element simulation of laser welded stainless steel plate2001In: Simulation of materials processing: theory, methods and applications : proceedings of the 7th International conference on numerical methods in industrial forming processes - NUMIFORM 2001 / [ed] Ken-ichiro Mori, Lisse: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 2001, p. 1119-1124Conference paper (Refereed)
  • 6.
    Fisk, Martin
    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.
    Simulation and validation of repair welding and heat treatment of an alloy 718 plate2012In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 58, p. 66-73Article in journal (Refereed)
    Abstract [en]

    This paper describes simulation of repair welding and heat treatment together with measurements for validation. The possibility to replace global heat treatment with local using induction heating is evaluated with respect to obtained residual stresses. A physically based material model is used in the analyses. The result from the residual stress measurement shows that there are no significant differences between local heat treatment and global heat treatment.

  • 7.
    Fisk, Martin
    et al.
    Materials Science and Applied Mathematics, Faculty of Technology and Society, Malmö University, Malmö University, Materials Science, Technology and Society, Malmö Högskola.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Andersson, Joel
    GKN Aerospace Engine Systems, Trollhättan.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Finite element analysis using a dislocation density based flow stress model coupled with model for precipitate evolution2014In: 8th International Symposium on Superalloy 718 and Derivatives / [ed] Eric Ott, John Wiley & Sons, 2014, p. 155-168Conference paper (Refereed)
    Abstract [en]

    Gas Tungsten Arc Welding is simulated using the finite element method. The material model that has been used is a physically based plasticity model, coupled with a model for nucleation, growth, and coarsening of second phase particles. The material model is well suited for thermo-mechanical simulations and is used to predict microstructural changes, residual stresses and stress relaxation after post weld heat treatment. The residual stress state after welding is compared, using two different material models. One were the evolution of the precipitates is included and one where it is not. It is shown that the welding direction has an impact on the precipitate size and its distribution and thereby the residual stress state.

  • 8.
    Fisk, Martin
    et al.
    Materials Science and Applied Mathematics, Faculty of Technology and Society, Malmö University, Malmö University, Materials Science, Technology and Society, Malmö Högskola.
    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.
    Zhou, J.M.
    Division of Production and Materials Engineering, Lund University.
    Simulation of microstructural evolution during repair welding of an IN718 plate2016In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 120, p. 92-101Article in journal (Refereed)
    Abstract [en]

    A precipitate evolution model based on classical nucleation, growth and coarsening theory is adapted and solved using the multi-class approach for the superalloy IN718. The model accounts for dissolution of precipitates and is implemented in a finite element program. The model is used to simulate precipitate evolution in the fused zone and the adjacent heat affected zone for a welding simulation. The calculated size distribution of precipitates is used to predict Vickers hardness. The simulation model is compared with nanoindentation experiments. The agreement between simulated and measured hardness is good.

  • 9.
    Karlsson, Dennis
    et al.
    Department of Chemistry – Ångström Laboratory, Uppsala University.
    Lindwall, Greta
    Royal Institute of Technology (KTH), Department of Material Science and Engineering.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Amnebrink, Mikael
    Sandvik Additive Manufacturing, Sandvik AB.
    Boström, Magnus
    Sandvik Additive Manufacturing, Sandvik AB.
    Riekehr, Lars
    Department of Chemistry – Ångström Laboratory, Uppsala University.
    Schuisky, Mikael
    Sandvik Additive Manufacturing, Sandvik AB.
    Sahlberg, Martin
    Department of Chemistry – Ångström Laboratory, Uppsala University.
    Jansson, Ulf
    Department of Chemistry – Ångström Laboratory, Uppsala University.
    Binder jetting of the AlCoCrFeNi alloy2019In: Additive Manufacturing, ISSN 2214-8604, Vol. 27, p. 72-79Article in journal (Refereed)
    Abstract [en]

    High density components of an AlCoCrFeNi alloy, often described as a high-entropy alloy, were manufactured by binder jetting followed by sintering. Thermodynamic calculations using the CALPHAD approach show that the high-entropy alloy is only stable as a single phase in a narrow temperature range below the melting point. At all other temperatures, the alloy will form a mixture of phases, including a sigma phase, which can strongly influence the mechanical properties. The phase stabilities in built AlCoCrFeNi components were investigated by comparing the as-sintered samples with the post-sintering annealed samples at temperatures between 900 °C and 1300 °C. The as-sintered material shows a dominant B2/bcc structure with additional fcc phase in the grain boundaries and sigma phase precipitating in the grain interior. Annealing experiments between 1000 °C and 1100 °C inhibit the sigma phase and only a B2/bcc phase with a fcc phase is observed. Increasing the temperature further suppresses the fcc phase in favor for the B2/bcc phases. The mechanical properties are, as expected, dependent on the annealing temperature, with the higher annealing temperature giving an increase in yield strength from 1203 MPa to 1461 MPa and fracture strength from 1996 MPa to 2272 MPa. This can be explained by a hierarchical microstructure with nano-sized precipitates at higher annealing temperatures. The results enlighten the importance of microstructure control, which can be utilized in order to tune the mechanical properties of these alloys. Furthermore, an excellent oxidation resistance was observed with oxide layers with a thickness of less than 5 μm after 20 h annealing at 1200 °C, which would be of great importance for industrial applications.

  • 10.
    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.

  • 11.
    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.

  • 12.
    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

  • 13.
    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.

  • 14.
    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.

  • 15.
    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.

  • 16.
    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.

  • 17.
    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)
  • 18.
    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.

  • 19.
    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.

  • 20.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    CAD support for heat input in a FE [finite element] model2002In: Mathematical Modelling of Weld Phenomena 6 / [ed] H. Cerjak; H.K.D.H. Bhadeshia, Maney Publishing (for The Institute of Materials, Minerals and Mining) , 2002, p. 1113-1121Conference paper (Refereed)
    Abstract [en]

    A method using CAD is presented for simplifying the problem of defining the heat input in finite element based welding simulations. The CAD system is used to define the weld path geometrically; this information is then used in the finite element analysis. Examples of the method's use are presented.

  • 21.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Finite element modelling and simulation of welding of aerospace components2003Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fusion welding is one of the most used methods for joining metals. This method has largely been developed by experiments, i.e. trial and error. The problem of distortion and residual stresses of a structure in and around a welded joint is important to control. This is especially important in the aerospace industry where the components are expensive and safety and quality are important issues. The safety requirements and the high costs of performing experiments to find different manufacturing routes is the motivation to increase the use of simulations in design of component as well as its manufacturing. Thus, in the case of welding, one can evaluate the effect of different fixtures, welding parameters etc on the deformation of the component. Then it is possible to optimise a chain of manufacturing processes as, for example, the welding residual stresses will affect the deformations during a subsequent heat treatment. The aim of the work presented in this thesis is to develop an efficient and reliable method and tool for simulation of the welding process using the Finite Element Method. The simulation tool will then be used when designing and planning the manufacturing of a component, so that introduction of new components can be made with as little disturbance as possible. In the same time the developed tool will be suitable for the task to perform an optimal design for manufacturing. Whilst this development will also be valuable in predicting the component's subsequent in-service behaviour, the key target is to ensure that designs are created which are readily manufactured. If this understanding is captured and made available to designers, true design for manufacture will result. This will lead to right first time product introduction and minimal ongoing manufacturing costs as process capability will be understood and designed into the component. When creating a numerical model, the aim is to implement the physical behaviour of the process into the computer model. However, it may be necessary to compromise between accuracy of the model and the required computational time. Different types of simplifications of the problem and more efficient computation methods are discussed. Methods for alleviating the modelling, and in particular the creation of the weld path, of complex geometries is presented. Simulations and experiments have been carried out on simple geometries in order to validate the models.

  • 22.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modelling and simulation of welding and metal deposition2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fusion welding is one of the most used methods for joining metals. This method has largely been developed by experiments, i.e. trial and error. The problem of distortion and residual stresses of a structure due to welding is important to control. This is especially important in the aerospace industry where the components are expensive and safety and quality are very important issues. The safety requirements and the high costs of performing experiments to find different manufacturing routes is the motivation to increase the use of simulations in design of components as well as its manufacturing. Thus, in the case of welding, one can evaluate the effect of different fixtures, welding parameters etc on the deformation of the component. The effects of previous processes are also important to consider, as well as it is important to bring forward the current state to subsequent processes.When creating a numerical model, the aim is to implement the physical behaviour of the process into the model. However, it may be necessary to compromise between accuracy of the model and the required computational time. The aim of the work presented in this thesis was to develop a method and model for simulation of welding and metal deposition of large and complex components using the finite element method. The model must be reliable and efficient to be usable in the designing and planning of the manufacturing of the component. In this thesis, the meaning of efficiency of a model is wider than just the computational efficiency. The time for creation and definition of the model should also be included. The developed methods enable the user to create a model for welding or metal deposition with a minimum of manual work. The method for defining weld paths and heat input together with activation of elements is now implemented in the commercial finite element software MSC.Marc. The implementation is based on the experience in this work and communication with the author. The approach has been validated against test cases. Naturally, this validation is dependent on sufficient accuracy of the heat input model and material model that are used. It is the first time a dislocation density model has been used to describe the flow stress in a welding simulation. The work has also demonstrated the possibility to calibrate heat input models with a physical based heat input model, thus relieving the need to calibrate the heat source versus measurements.Efficiency in terms of computing time has also been investigated in the course of this work. Three different methods has been explored and used, adaptive meshing, substructuring and parallel computation. The method that is found to be the most versatile and reduce the overall simulation time the most is parallel computation. It is straightforward for the user to employ and it introduces no reduction in the accuracy.

  • 23.
    Lundbäck, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Alberg, Henrik
    Henrikson, Per
    Simulation and validation of TIG-welding and post weld heat treatment of an Inconel 718 plate2005In: Mathematical modelling of weld phenomena 7: [papers presented at the Seventh International Seminar 'Numerical Analysis of Weldability' held from 29th of September to 1st of October 2003 at Schloss Seggau near Graz, Austria] / [ed] Horst Cerjak; H.K.D.H. Bhadeshia, Graz: Techn. Univ. TYG , 2005, p. 683-696Conference paper (Refereed)
    Abstract [en]

    A finite element based model was used to simulate the thermal and mechanical response of a simple geometry TIG welded joint, validated through experiments. TIG welding experiments were carried out to produce butt welds in Inconel 718 sheets of thickness 3.2 mm, followed by heat treatment. Transient temperature and strain measurements were performed during welding; residual stress measurements were carried out after welding and after heat treatment. Calculated and measured welding temperature histories, strains and residual stresses were compared. The effect of buckling occurrence on the sensitivity of the model is noted.

  • 24.
    Lundbäck, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Fisk, Martin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Repair welding and local heat treatment2014In: Encyclopedia of Thermal Stresses, Dordrecht: Encyclopedia of Global Archaeology/Springer Verlag, 2014, p. 4186-4194Chapter in book (Refereed)
  • 25.
    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)
  • 26.
    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.

  • 27.
    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.

  • 28.
    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.

  • 29.
    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.

  • 30.
    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.

  • 31.
    Lundbäck, Andreas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Runnemalm, Henrik
    Luleå tekniska universitet.
    Validation of three-dimensional finite element model for electron beam welding of Inconel 7182005In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 10, no 6, p. 717-724Article in journal (Refereed)
    Abstract [en]

    A three-dimensional finite element model for the prediction of the distortion and residual stresses induced during electron beam welding is described. The model is validated by butt welding experiments on two Inconel 718 plates. A particular effort is made to determine a good model for the heat input. A combined conical and double ellipsoid heat source is used to model the deep penetration characteristic of the electron beam and this source is calibrated using the results from a separate thermodynamic simulation, using the ELSIM finite difference code. Parallel computation is used to reduce the overall simulation time in the coupled thermomechanical simulation of welding. The agreement between calculations and experiments is good with respect to the residual stresses. Measured and computed deformations agree qualitatively although they differ in magnitude

  • 32.
    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)
  • 33. Saracibar, C. Agelet de
    et al.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Chiumenti, M.
    Cervera, M.
    Shaped Metal Deposition Processes2014In: Encyclopedia of Thermal Stresses, Dordrecht: Encyclopedia of Global Archaeology/Springer Verlag, 2014, p. 4347-4355Chapter in book (Refereed)
    Abstract [en]

    The shaped metal deposition (SMD) process is a novel manufacturing technology which is similar to the multi-pass welding used for building features such as lugs and flanges on components [1–7]. This innovative technique is of great interest due to the possibility of employing standard welding equipment without the need for extensive new investment [8, 9]. The numerical simulation of SMD processes has been one of the research topics of great interest over the last years and requires a fully coupled thermo-mechanical formulation, including phase-change phenomena defined in terms of both latent heat release and shrinkage effects [1–6]. It is shown how computational welding mechanics models can be used to model SMD for prediction of temperature evolution, transient, as well as residual stresses and distortions due to the successive welding layers deposited. Material behavior is characterized by a thermo-elasto-viscoplastic constitutive model coupled

  • 34. Söderberg, Magnus
    et al.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Combination of Geometrical Simplification Techniques for Very Large Welded Structures Using Symmetry2013In: Mathematical modelling of weld phenomena 10: [papers presented at the Seventh International Seminar 'Numerical Analysis of Weldability' held from 24th of September to 26th of September, 2012 at Schloss Seggau near Graz, Austria] / [ed] Christof Sommitsch; Norbert Enzinger, Graz: Verl. der Techn. Univ. Graz , 2013, p. 287-299Conference paper (Refereed)
  • 35.
    Söderberg, Magnus
    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.
    Modeling of metal deposition2013In: Trends in welding research: proceedings of the 9th International Conference on Trends in Welding Research, June 4-8, 2012, Hilton Chicago/Indian Lakes Resort, Chicago, Illinois, USA / [ed] Tarasankar DebRoy, Materials Park, OH: ASM International, 2013, p. 853-858Conference paper (Refereed)
    Abstract [en]

    Modeling and simulation of metal deposition with focus on alleviating the work of the modeler is presented in this paper. The usage of dissimilar meshes for the base plate and the material to be deposited is investigated. The nodes that reside in the interface between the base plate and added material are connected with so called glued contact. The results are compared with previously published results from a model with identical geometry and process parameters. Measurements from the previous study are also included. The temperature results show very good agreement between the models and measurements. Observed deviations in deformation results between the reference simulations and the computed results are believed to originate from the element activation procedure in combination with the contact approach. Overall, the method is considered to have potential for facilitating the process of modeling and simulating metal deposition.

  • 36.
    Tersing, Henrik
    et al.
    Volvo Aero Corporation.
    Lorentzon, John
    Volvo Aero Corporation.
    Francois, Arnaud
    Cenaero.
    Lundbäck, Andreas
    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.
    Barboza, Josué
    Cenaero.
    Bäcker, Vladimir
    Laboratory for Machine Tools and Production Engineering of RWTH Aachen University.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Simulation of manufacturing chain of a titanium aerospace component with experimental validation2012In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 51, p. 10-21Article in journal (Refereed)
    Abstract [en]

    Manufacturing of advanced components like aeroengine parts is performed in a global network. Different manufacturers deliver individual components to the engine and even different manufacturing steps for a given component may be performed at different companies. Furthermore, quality is of utmost importance in this context. Simulations are increasingly used to assure the latter. The current paper describes the simulation of a chain of manufacturing processes for an aeroengine component. Different partners have performed the simulations of the different steps using a variety of finite element codes. The results are discussed in the paper and particularly the lessons learned regarding the modelling process.

  • 37.
    Wärmefjord, Kristina
    et al.
    Department of Product and Production Development, Chalmers University of Technology.
    Söderberg, Rikard
    Department of Product and Production Development, Chalmers University of Technology.
    Ericsson, Mikael
    University West, Department of Engineering Science, 461 32 Trollhättan.
    Appelgren, Anders
    University West, Department of Engineering Science, 461 32 Trollhättan.
    Lundbäck, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lööf, Johan
    GKN Aerospace Engine Systems, Trollhättan.
    Lindkvist, Lars
    Department of Product and Production Development, Chalmers University of Technology.
    Svensson, Hans-Olof
    GKN Aerospace Engine Systems, Trollhättan.
    Welding of Non-nominal Geometries: Physical Tests2016In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 43, p. 136-141Article in journal (Refereed)
    Abstract [en]

    The geometrical quality of a welded assembly is to some extent depending part positions before welding. Here, a design of experiment is set up in order to investigate this relation using physical tests in a controlled environment. Based on the experimental results it can be concluded that the influence of part position before welding is significant for geometrical deviation after welding. Furthermore, a working procedure for a completely virtual geometry assurance process for welded assemblies is outlined. In this process, part variations, assembly fixture variations and welding induced variations are important inputs when predicting the capability of the final assembly.

1 - 37 of 37
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