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  • 1.
    Draxler, Joar
    et al.
    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.
    Andersson, J.
    University West, Trollhättan, Sweden.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modeling and simulation of weld solidification cracking part I: A pore-based crack criterion2019In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, no 5, p. 1489-1502Article in journal (Refereed)
    Abstract [en]

    Several advanced alloy systems are susceptible to weld solidification cracking. One example is nickel-based superalloys, which are commonly used in critical applications such as aerospace engines and nuclear power plants. Weld solidification cracking is often expensive to repair and, if not repaired, can lead to catastrophic failure. This study, presented in three papers, presents an approach for simulating weld solidification cracking applicable to large-scale components. The results from finite element simulation of welding are post-processed and combined with models of metallurgy, as well as the behavior of the liquid film between the grain boundaries, in order to estimate the risk of crack initiation. The first paper in this study describes the crack criterion for crack initiation in a grain boundary liquid film. The second paper describes the model for computing the pressure and the thickness of the grain boundary liquid film, which are required to evaluate the crack criterion in paper 1. The third and final paper describes the application of the model to Varestraint tests of alloy 718. The derived model can fairly well predict crack locations, crack orientations, and crack widths for the Varestraint tests. The importance of liquid permeability and strain localization for the predicted crack susceptibility in Varestraint tests is shown.

  • 2.
    Draxler, Joar
    et al.
    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.
    Andersson, J.
    University West, Trollhättan, Sweden.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modeling and simulation of weld solidification cracking part II: A model for estimation of grain boundary liquid pressure in a columnar dendritic microstructure2019In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, no 5, p. 1503-1519Article in journal (Refereed)
    Abstract [en]

    Several advanced alloy systems are susceptible to weld solidification cracking. One example is nickel-based superalloys, which are commonly used in critical applications such as aerospace engines and nuclear power plants. Weld solidification cracking is often expensive to repair, and if not repaired, can lead to catastrophic failure. This study, presented in three papers, presents an approach for simulating weld solidification cracking applicable to large-scale components. The results from finite element simulation of welding are post-processed and combined with models of metallurgy, as well as the behavior of the liquid film between the grain boundaries, in order to estimate the risk of crack initiation. The first paper in this study describes the crack criterion for crack initiation in a grain boundary liquid film. The second paper describes the model for computing the pressure and the thickness of the grain boundary liquid film, which are required to evaluate the crack criterion in paper 1. The third and final paper describes the application of the model to Varestraint tests of Alloy 718. The derived model can fairly well predict crack locations, crack orientations, and crack widths for the Varestraint tests. The importance of liquid permeability and strain localization for the predicted crack susceptibility in Varestraint tests is shown.

  • 3.
    Draxler, Joar
    et al.
    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.
    Andersson, J.
    University West, Trollhättan, Sweden.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modeling and simulation of weld solidification cracking part III: Simulation of solidification cracking in Varestraint tests of alloy 7182019In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, no 6, p. 1883-1901Article in journal (Refereed)
    Abstract [en]

    Several advanced alloy systems are susceptible to weld solidification cracking. One example is nickel-based superalloys, which are commonly used in critical applications such as aerospace engines and nuclear power plants. Weld solidification cracking is often expensive to repair, and if not repaired, can lead to catastrophic failure. This study, presented in three papers, presents an approach for simulating weld solidification cracking applicable to large-scale components. The results from finite element simulation of welding are post-processed and combined with models of metallurgy, as well as the behavior of the liquid film between the grain boundaries, in order to estimate the risk of crack initiation. The first paper in this study describes the crack criterion for crack initiation in a grain boundary liquid film. The second paper describes the model required to compute the pressure and thickness of the liquid film required in the crack criterion. The third and final paper describes the application of the model to Varestraint tests of alloy 718. The derived model can fairly well predict crack locations, crack orientations, and crack widths for the Varestraint tests. The importance of liquid permeability and strain localization for the predicted crack susceptibility in Varestraint tests is shown.

  • 4.
    Draxler, Joar
    et al.
    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.
    Andersson, J.
    University West, 46132 Trollhättan, Sweden.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Simulation of weld solidifiation cracking in varestraint tests of alloy 7182019In: Mathematical Modelling of Weld Phenomena 12: Selected peer reviewed papers from the 12th International Seminar Numerical Analysis of Weldability / [ed] C. Sommitsch, N. Enzinger, P. Mayr, Gratz, 2019, p. 485-504Conference paper (Refereed)
    Abstract [en]

    Several nickel-based superalloys are susceptible to weld solidification cracking. Numerical simulation can be a powerful tool for optimizing the welding process such that solidification cracking can be avoided. In order to simulate the cracking, a crack model inspired by the RDG model is proposed. The model is based on a crack criterion that estimates the likelihood for a preexisting pore in a grain boundary liquid film to form a crack. The criterion depends on the thickness and the liquid pressure in the grain boundary liquid film, as well as the surface tension of the pore. The thickness of the liquid film is computed from the macroscopic mechanical strain field of an FE model with a double ellipsoidal heat source. A temperature-dependent length scale is used to partition the macroscopic strain to the liquid film. The liquid pressure in the film is evaluated using a combination of Poiseuille parallel plate flow and Darcy’s law for porous flows. The Poiseuille flow is used for the part of the grain boundary liquid film that extends into the region with liquid fraction less than 0.1, while Darcy’s law is used for the rest of the liquid film that extends into the regions with liquid fraction greater than 0.1. The proposed model was calibrated and evaluated in Varestraint tests of Alloy 718. Crack location, width, and orientation were all accurately predicted by the model.

  • 5.
    Draxler, Joar
    et al.
    University West, 46132, Trollhättan, Sweden.
    Åkerström, Paul
    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.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Singh, S.
    Chalmers University of Technology, 41296, Göteborg, Sweden.
    Raza, T.
    University West, 46132, Trollhättan, Sweden.
    Andersson, J.
    University West, 46132, Trollhättan, Sweden.
    A numerical model for simulating the effect of strain rate on eutectic band thickness2020In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 64, no 10, p. 1635-1658Article in journal (Refereed)
    Abstract [en]

    Large tensile strains acting on the solidifying weld metal can cause the formation of eutectic bands along grain boundaries. These eutectic bands can lead to severe liquation in the partially melted zone of a subsequent overlapping weld. This can increase the risk of heat-affected zone liquation cracking. In this paper, we present a solidification model for modeling eutectic bands. The model is based on solute convection in grain boundary liquid films induced by tensile strains. The proposed model was used to study the influence of strain rate on the thickness of eutectic bands in Alloy 718. It was found that when the magnitude of the strain rate is 10 times larger than that of the solidification rate, the calculated eutectic band thickness is about 200 to 500% larger (depending on the solidification rate) as compared to when the strain rate is zero. In the paper, we also discuss how eutectic bands may form from hot cracks.

  • 6.
    Edberg, J
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Draxler, J
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Andersson, J
    University West.
    Comparison of two different indicators for hot cracking in welded structures2018In: ICAS 2018: 31st Congress of the International Council of Aeronautical Sciences, The International Council of the Aeronautical Sciences , 2018, article id ICAS2018_0142Conference paper (Refereed)
    Abstract [en]

    Welding simulations of the nickel-based superalloy Alloy 718 have been performed, combined with two fundamentally different hot crack indicators. The purpose of the indicators was to evaluate the risk of hot crack development in the weld. The result of the simulations has been compared with experiments. Advantages and limitations of the two hot crack indicators are discussed. Regions with a high value of the indicators in the simulations agree well with regions with hot cracks in the experiments.

  • 7.
    Edberg, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Computational modeling of hot rolling1993Licentiate thesis, comprehensive summary (Other academic)
  • 8.
    Edberg, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Computational modeling of hot rolling1996Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis consists of six papers on finite element simulations of the hot rolling of plates. Different friction and material models have been evaluated. The work includes both numerical simulation and experimental verification. It is shown that the constitutive model for the plate material is more important than the model for the friction between the rolled material and the rolls. It was also found that an explicit finite element method is more effective and easier to use than an implicit code. The models presented are one step towards a general and more complete computational model of flat rolling. They are not complete as they depend on a separate estimation of the roll bending. Otherwise, all three-dimensional aspects of the rolling process are included. The material models used work quite well for the simulation of the hot rolling operation. High accuracy is obtained for global quantities like rolling force and torque. A better material model would improve the prediction of the stress distribution in the rolled material. It should be able to describe the effect of rapidly changing strain rates and temperatures during deformation as well as recrystallization and thermal strains.

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  • 9.
    Edberg, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Three-dimensional simulation of plate rolling using different friction models1992In: Numerical methods in industrial forming processes: proceedings of the 4th International Conference on Numerical Methods in Industrial Forming Processes, Valbonne/France, 14-18 September 1992; NUMIFORM '92 / [ed] J.L. Chenot; R.D. Wood; O.C. Zienkiewicz, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1992Conference paper (Refereed)
  • 10.
    Edberg, Jonas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Andersson, Joel
    University West, Department of Engineering Science, 461 86 Trolhättan.
    Use of Indicators for Hot and Warm Cracking in Welded Structures2016In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 7, p. 145-150Article in journal (Refereed)
    Abstract [en]

    Weight reduction of mechanical components is becoming increasingly important as a way to provide more environment friendly production and operation of different equipment. This is true in almost any manufacturing industry, but is especially important to the aerospace industry. Casting has often been replaced by hot and cold metal working operations and welding, usually including an additional heat treatment. This gives components better material properties and provides components with less weight and cost but with increased strength and efficiency. This may even be true for rotating Ni- based superalloy components, and is enabled by welding methods. However, weld cracking of precipitation hardening Ni-based superalloys is a serious problem, both in manufacturing and overhaul since it endangers component life if cracks are allowed to propagate.

    Cracks can appear in a weld and in it's surroundings. The triggering mechanisms depend on its location and when it is nucleated. Generally saying, weld cracking in precipitation hardening Ni-based superalloys consists of two different types of cracking, hot cracking and warm cracking which may be further divided into heat affected zone (HAZ) liquation cracking, solidification cracking and strain age cracking, respectively.

    Finite element simulations of welding and heat treatment processes started in the seventies for small laboratory set-up cases and have today matured, and are now used on large-scale structures like aerospace components. But FE-based crack criteria that can predict the risk of cracking due to welding or heat treatments are rare. In a recent study both hot cracking and warm cracking have been investigated in Ni-based superalloys, and two FE-based indicators showing the risk of hot and warm cracks have been proposed. The objective of the investigation presented in this paper is to compare results from FE-simulations with experimental results from weldability tests, like the Varestraint test and the high temperature mechanical Gleeble test.

  • 11.
    Edberg, Jonas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Larsson, Dan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Simulation of braking of railway wheel2003Report (Other academic)
    Abstract [en]

    LKAB has tried new iron ore wagons for the 30 tonnes axle load. They got problems with cracking and material removal from the rim of the wheels during the tests. Martensite, which is more prone to cracking than other microstructures, was found at these locations. The initial material microstructure is supposed to contain no martensite. The purpose of this investigation is to find whether the thermal cycle due to braking, possibly with assistance of the mechanical load, can cause martensite formation

  • 12.
    Edberg, Jonas
    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.
    Efficient three-dimensional model of rolling using an explicit finite-element formulation1993In: Communications in Numerical Methods in Engineering, ISSN 1069-8299, E-ISSN 1099-0887, Vol. 9, no 7, p. 613-627Article in journal (Refereed)
    Abstract [en]

    Rolling is simulated by a three-dimensional finite-element model with elastoplastic constitutive equations. The use of an explicit finite-element formulation, instead of the more commonly used implicit formulation, has reduced the required computing time. The larger of the models used in one step towards a general and complete computational model of rolling. Results from experiments and from two and three-dimensional calculations are compared.

  • 13.
    Edberg, Jonas
    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.
    Wedge rolling test1994In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 42, no 2, p. 227-238Article in journal (Refereed)
    Abstract [en]

    A method for the evaluation of friction models is described. A wedge is rolled to uniform thickness, a range of reductions being investigated thereby in one experiment. Finite-element simulations are performed in order to estimate the friction parameters that can be used in the simulation of hot rolling. The influence of the material parameters and the friction parameters on the calculated results are investigated and the latter are compared with experimental results. It is shown that it is possible to separate the influence of the material parameters and the friction parameters, thus enabling the friction parameters to be evaluated from a minimum number of experiments.

  • 14.
    Edberg, Jonas
    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.
    Ken-Ichiro, M.
    Shot peening simulated by two different finite element formulations1995In: Simulation of materials processing: theory, methods and applications ; proceedings of the Fifth International Conference on Numerical Methods in Industrial Forming Processes - NUMIFORM'95, Ithaca, New York, USA, 18-21 June 1995 / [ed] Shan-Fu Shen; Paul Dawson, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1995Conference paper (Refereed)
  • 15.
    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.

  • 16. Kalhori, Vahid
    et al.
    Lindgren, Lars-Erik
    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.
    Coupled thermomechanical simulation of hot rolling using an adaptive mesh1998In: Simulation of materials processing : theory, methods and applications: international conference on numerical methods in industrial forming processes, NUMIFORM '98 / [ed] J. Huétink; F.P.T. Baaijens, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1998, p. 689-693Conference paper (Refereed)
    Abstract [en]

    Coupled thermo-mechanical analysis of hot rolling is performed. The efficiency and accuracy when using an adaptive remeshing technique is compared with using a uniform, fine mesh. The advantages and limitations of the different techniques are discussed

  • 17.
    Lindgren, Lars-Erik
    et al.
    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.
    Contact forces and deformations in plate rolling1989In: Numerical methods in industrial forming processes: proceedings of the 3rd International Conference on Numerical Methods in Industrial Forming Processes, Fort Collins, Colorado, 26 - 30 June 1989 / NUMIFORM 89 / [ed] Erik G. Thompson, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1989, p. 331-336Conference paper (Refereed)
  • 18.
    Lindgren, Lars-Erik
    et al.
    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.
    Explicit versus implicit finite element formulation in simulation of rolling1990In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 24, p. 85-94Article in journal (Refereed)
    Abstract [en]

    The computational efficiency of the explicity finite element code DYNA2D and the implicit code NIKE2D are compared in the case of simulation of rolling. It is found that the explicit code is preferable. The advantages of the explicit formulation will be even more pronounced in three-dimensional simulations

  • 19.
    Lindgren, Lars-Erik
    et al.
    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.
    Åkerström, Paul
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Zhang, Zhao
    Dalian University of Technology, Dalian, China.
    Modeling of thermal stresses in low alloy steels2019In: Journal of thermal stresses, ISSN 0149-5739, E-ISSN 1521-074X, Vol. 42, no 6, p. 725-743Article in journal (Refereed)
    Abstract [en]

    Computing the evolution of thermal stresses accurately requires appropriate constitutive relations. This includes both the thermal and mechanical aspects, as temperature is the driver to thermal stresses. The paradigm of Integrated Computational Materials Engineering (ICME) aims at being able to quantitatively relate process-structure-property of a material. The article describes physics based models, denoted bridging elements, which are one step towards the vision of ICME. They couple material structure with heat capacity, heat conductivity, thermal and transformation strains and elastic properties for hypo-eutectoid steels. The models can account for the chemical composition of the steel and its processing, i.e. thermomechanical history, giving the evolution of the microstructure and the corresponding properties.

  • 20.
    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

  • 21.
    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.

  • 22.
    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

  • 23.
    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.

  • 24.
    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.

  • 25.
    Olaogun, O.
    et al.
    Department of Mechanical Engineering Science, University of 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, Nigeria.
    Akinlabi, E.T.
    Department of Mechanical Engineering Science, University of Johannesburg, South Africa.
    Modelling and simulation of the first pass in industrial cold rolling process of Aluminium 8015 alloy2018In: 11th South African Conference on Computational and Applied Mechanics, SACAM 2018, South African Association for Theoretical and Applied Mechanics (SAAM) , 2018, p. 314-321Conference paper (Refereed)
    Abstract [en]

    The cold rolling process is a strain-hardening mechanism, which is widely known for its strength improvement, excellent surface finish and dimensional tolerance. This work aims to model and simulate the first pass of the industrial cold rolling process of Aluminium 8015 alloy. Process parameters are obtained from practical industrial cold rolling of the aluminium alloy and are used in the development of 2-D and 3-D finite element models for the first pass. These were achieved using the MSC Marc-Mentat Software. Research results comprising of the roll force, contact frictional force, and shear stress were investigated. Findings reveal the deformation rate pattern and neutral points in the roll bite. The 3-D finite element model developed is effective in analyzing deformation of metals in the roll bite as compared to the 2-D model.

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