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  • 1.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Gyhlesten Back, Jessica
    Department of Materials Technology, Dalarna University, Falun, Sweden.
    Elastic properties of ferrite and austenite in low alloy steels versus temperature and alloying2019In: Materialia, ISSN 2589-1529, Vol. 5, article id 100193Article in journal (Refereed)
    Abstract [en]

    Models for elastic properties, as a function of temperature, are required when simulating various thermo-mechanical processes. A model for hypoeutectoid steels is proposed that accounts for this temperature dependency as well as the influence of alloying. The model consists of separate parts for the ferrite and austenite phases. The latter also includes a specific contribution due to ferromagnetism. The model is calibrated versus iron and evaluated against various steels.

  • 2.
    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.

  • 3.
    Gyhlesten Back, Jessica
    et al.
    Högskolan Dalarna, Industriell Teknik, Materialvetenskap.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Influence of prior deformation in austenite on the martensite formation in a low-alloyed carbon steel2019In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 941, p. 95-99Article in journal (Refereed)
    Abstract [en]

    The current work aims at developing models supporting design of the rolling and quenching processes. This requires a martensite formation model that can account for effect of previous plastic deformation as well as evolution of stress and temperature during the quenching step. The effect of deformation prior to the cooling on the transformation is evaluated. The experimental result shows that prior deformation impedes the martensite transformation due to the mechanical stabilisation of the austenite phase. Larger deformation above 30 % reduces the effect of the mechanical stabilisation due to increase in martensite nucleation sites. The computed transformation curves, based on an extended version of the Koistinen-Marburger equation, agree well with experimental results for pre-straining less than 30 %.

  • 4.
    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.

  • 5.
    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.

  • 6.
    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.

  • 7.
    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.

  • 8.
    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.

  • 9.
    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.

  • 10.
    Fisk, Martin
    et al.
    Materials Science and Applied Mathematics, Malmö University.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Datchary, W.
    AB SKF.
    Deshmukh, V.
    AB SKF.
    Modelling of induction hardening in low alloy steels2018In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925, Vol. 144, p. 61-75Article in journal (Refereed)
    Abstract [en]

    Induction hardening is a useful method for improving resistance to surface indentation, fatigue and wear that is favoured in comparison with through hardening, which may lack necessary toughness. The process itself involves fast heating by induction with subsequent quenching, creating a martensitic layer at the surface of the workpiece. In the present work, we demonstrate how to simulate the process of induction hardening using a commercial finite element software package with focuses on validation of the electromagnetic and thermal parts, together with evolution of the microstructure. Experiments have been carried out using fifteen workpieces that have been heated using three different heating rates and five different peak temperatures resulting in different microstructures. It is found that the microstructure and hardening depth is affected by the heating rate and peak temperature. The agreement between the experimental and simulated results is good. Also, it is demonstrated that the critical equilibrium temperatures for phase transformation is important for good agreement between the simulated and experimental hardening depth. The developed simulation technique predicts the hardness and microstructure sufficiently well for design and the development of induction hardening processes.

  • 11.
    Babu, Bijish
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Charles, Corinne
    Department of Industrial Production, Högskolan Väst, Trollhättan.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Physically Based Constitutive Model of Ti-6Al-4V for Arbitrary Phase Composition2018In: International journal of plasticity, ISSN 0749-6419, E-ISSN 1879-2154Article in journal (Refereed)
    Abstract [en]

    The principal challenge in producing aerospace components using Ti-6Al-4V alloy is to employ the optimum process window of deformation rate and temperature to achieve desired material properties. Qualitatively understanding the microstructure-property relationship is not enough to accomplish this goal. Developing advanced material models to be used in manufacturing process simulation is the key to compute and optimize the process iteratively. The focus in this work is on physically based flow stress models coupled with microstructure evolution models. Such a model can be used to simulate processes involving complex and cyclic thermo-mechanical loading.

  • 12.
    Zamani, Mohammadreza
    et al.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University.
    Dini, Hoda
    Department of Materials and Manufacturing, School of Engineering, Jönköping University.
    Svoboda, Ales
    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.
    Seifeddine, Salem
    Department of Materials and Manufacturing, School of Engineering, Jönköping University.
    Andersson, Nils-Eric
    Department of Materials and Manufacturing, School of Engineering, Jönköping University.
    Jarfors, Anders E.W.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University.
    A dislocation density based constitutive model for as-cast Al-Si alloys: Effect of temperature and microstructure2017In: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 121, p. 164-170Article in journal (Refereed)
    Abstract [en]

    The flow stress of an as-cast Al-Si based alloy was modeled using a dislocation density based model. The developed dislocation density-based constitutive model describes the flow curve of the alloy with various microstructures at quite wide temperature range. Experimental data in the form of stress-strain curves for different strain rates ranging from 10−4 to 10−1 s−1 and temperatures ranging from ambient temperature up to 400 °C were used for model calibration. In order to model precisely the hardening and recovery process at elevated temperature, the interaction between vacancies and dissolved Si was included. The calibrated temperature dependent parameters for different microstructure were correlated to the metallurgical event of the material and validated. For the first time, a dislocation density based model was successfully developed for Al-Si cast alloys. The findings of this work expanded the knowledge on short strain tensile deformation behaviour of these type of alloys at different temperature, which is a critical element for conducting a reliable microstructural FE-simulation.

  • 13.
    Azizoğlu, Yağız
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Gärdsback, Mattias
    Sandvik Materials Technology, R&D, Sandviken.
    Sjöberg, Bengt
    Sandvik Materials Technology, R&D, Sandviken.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Finite Element Analysis of cold pilgering using elastic roll dies2017In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 207, p. 2370-2375Article in journal (Refereed)
    Abstract [en]

    A finite element model of cold pilgering with elastic roll dies have been developed and used to investigate the influence of roll die deformation on the material flow, contact region, roll separating force and tube dimensions. Full scale experiments were performed to validate the contact surface and tube dimensions. The results show that the influence of roll die flattening is not significant on the contact length. However, elastic deformation of roll die has strong influence on both the wall thickness reduction and roll separating force. Thus it is recommended to consider elasticity of roll dies when forces and tube dimensions are estimated.

  • 14.
    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.

  • 15.
    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)
  • 16.
    Thipprakmas, Sutasn
    et al.
    Department of Tool and Materials Engineering, King Mongkut's University of Technology Thonburi, Bangkok.
    Joun, Man Soo
    School of Mechanical Engineering, Engineering Research Institute, Gyeongsang National University.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modern Engineered Materials and Technologies for Metal Forming Applications2017In: Advances in Materials Science and Engineering, ISSN 1687-8434, E-ISSN 1687-8442, Vol. 2017, article id 3196509Article in journal (Refereed)
  • 17.
    Abiri, Olufunminiyi
    et al.
    Institute of Intelligent Systems, University of Johannesburg.
    Wedberg, Dan
    AB Sandvik Coromant.
    Svoboda, Ales
    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.
    Non-Local Modelling of Strain Softening in Machining Simulations2017In: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 225, article id 012053Article in journal (Refereed)
    Abstract [en]

    Non-local damage model for strain softening in a machining simulation is presented in this paper. The coupled damage-plasticity model consists of a physically based dislocation density model and a damage model driven by plastic straining in combination with the stress state. The predicted chip serration is highly consistent with the measurement results. 

  • 18.
    Zhang, Zhao
    et al.
    State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology.
    Wan, Zhenyu
    State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Tan, Z.J.
    State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology.
    Zhou, Xia
    State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology.
    The Simulation of Precipitation Evolutions and Mechanical Properties in Friction Stir Welding with Post-Weld Heat Treatments2017In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 26, no 12, p. 5731-5740Article in journal (Refereed)
    Abstract [en]

    A finite element model of friction stir welding capable of re-meshing is used to simulate the temperature variations. Re-meshing of the finite element model is used to maintain a fine mesh resolving the gradients of the solution. The Kampmann–Wagner numerical model for precipitation is then used to study the relation between friction stir welds with post-weld heat treatment (PWHT) and the changes in mechanical properties. Results indicate that the PWHT holding time and PWHT holding temperature need to be optimally designed to obtain FSW with better mechanical properties. Higher precipitate number with lower precipitate sizes gives higher strength in the stirring zone after PWHT. The coarsening of precipitates in HAZ are the main reason to hinder the improvement of mechanical property when PWHT is used.

  • 19.
    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)
  • 20.
    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)
  • 21.
    Abiri, Olufunminiyi
    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.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Comparison of Multiresolution Continuum Theory and Nonlocal Dame model for use in Simulation of Manufacutring Processes2016In: International Journal for Multiscale Computational Engineering, ISSN 1543-1649, Vol. 14, no 1, p. 81-94Article in journal (Refereed)
    Abstract [en]

    Modelling and simulation of manufacturing processes may require the capability to account for localization behavior, often associated with damage/fracture. It may be unwanted localization indicating a failure in the process or, as in the case of machining and cutting, a wanted phenomenon to be controlled. The latter requires a higher accuracy regarding the modelling of the underlying physics, as well as the robustness of the simulation procedure. Two different approaches for achieving mesh-independent solutions are compared in this paper. They are the multiresolution continuum theory (MRCT) and nonlocal damage model. The MRCT theory is a general multilength-scale finite element formulation, while the nonlocal damage model is a specialized method using a weighted averaging of softening internal variables over a spatial neighborhood of the material point. Both approaches result in a converged finite element solution of the localization problem upon mesh refinement. This study compares the accuracy and robustness of their numerical schemes in implicit finite element codes for the plane strain shear deformation test case. Final remarks concerning ease of implementation of the methods in commercial finite element packages are also given.

  • 22.
    Abiri, Olufunminiyi
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials. University of Johannesburg, South Africa.
    Svoboda, Ales
    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.
    Wedberg, Dan
    Controlling Thermal Softening Using Non-Local Temperature Field in Modelling2016In: Journal of Machining and Forming Technologies, ISSN 1947-4369, Vol. 8, no 1-2, p. 13-28Article in journal (Refereed)
    Abstract [en]

    One of the aims of this work is to show that thermal softening due to the reduced flow strength of a material with increasing temperature may cause chip serrations to form during machining. The other purpose, the main focus of the paper, is to demonstrate that a non-local temperature field can be used to control these serrations. The non-local temperature is a weighted average of the temperature field in the region surrounding an integration point. Its size is determined by a length scale. This length scale may be based on the physics of the process but is taken here as a regularization parameter.

  • 23.
    Azizoğlu, Yağız
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Gärdsback, Mattias
    Sandvik Mat Technol, R&D, SE-81181 Sandviken.
    Sjöberg, Bengt
    Sandvik Mat Technol, R&D, SE-81181 Sandviken.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Finite element modeling of tube deformation during cold pilgering2016In: NUMIFORM 2016: The 12th International Conference on Numerical Methods in Industrial Forming Processes / [ed] Saanouni, K; Chenot, JL; Duval, JL, 2016, Vol. 80, p. 1-8, article id 15004Conference paper (Refereed)
    Abstract [en]

    A three-dimensional finite element model of cold pilgering of stainless steel tubes is developed in this paper. The objective is to use the model to increase the understanding of forces and deformations in the process. The focus is on the influence of vertical displacements of the roll stand and axial displacements of the mandrel and tube. Therefore, the rigid tools and the tube are supported with elastic springs. Additionally, the influences of friction coefficients in the tube/mandrel and tube/roll interfaces are examined. A sensitivity study is performed to investigate the influences of these parameters on the strain path and the roll separation force. The results show the importance of accounting for the displacements of the tube and rigid tools on the roll separation force and the accumulative plastic strain.

  • 24.
    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.

  • 25.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Integrated Design of Material, Manufacturing, Product and Performance2016In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 7, p. 53-58Article in journal (Refereed)
    Abstract [en]

    The ever-increasing emphasis on sustainable growth affects mechanical engineering tremendously. The components and products must be efficient, durable and light. Potential cost and weight savings without compromising performance can be realized by extending the design space of engineering design to include manufacturing process as well as material chemistry. This requires more advanced computational support than what is common in today's Computer Aided Design. The paper proposes a modelling approach for evaluation the integrated effects of material and manufacturing on component performance. Material and process models are the key ingredients and are exemplified in the paper.

  • 26.
    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.

  • 27.
    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.

  • 28.
    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

  • 29.
    Azizoğlu, Yağız
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Gärdsback, Mattias
    Dalarna University.
    Sjöberg, Bengt
    Dalarna University.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Finite Element Modelling of Cold Pilgering of Tubes2015In: 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. 716-726Conference paper (Refereed)
    Abstract [en]

    Cold pilgering is a cold forming process used during manufacturing of seamless tubes. The tube with a mandrel inside is fed forward and rotated in stepwise increments, while the roll stand moves back and forth. The total plastic deformation of the tube is such that the cross-sectional area of the tube decreases and the length of the tube increases during the process. However, this is performed in many small incremental steps, where the direction of deformation in a material point changes at each stroke. Most published models of cold pilgering use simplified material models. In reality, the flow stress is dependent on temperature, strain rate, strain history and microstructure. In this work, temperature and strain rate distributions are computed, using a 3D thermo-mechanical FE model, and the influence of temperature and strain rate on the rolling force is investigated. The Johnson-Cook model is employed to describe the flow stress using isotropic hardening. The results show that strain rate and temperature have a significant influence on the roll separation force

  • 30.
    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.
    Liu, Wing Kam
    Northwestern University, Department of Mechanical Engineering, Evanston, IL.
    Smith, Jacob
    Northwestern University, Evanston.
    Implicit finite element formulation of multiresolution continuum theory2015In: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, E-ISSN 1879-2138, Vol. 293, p. 114-130Article in journal (Refereed)
    Abstract [en]

    The multiresolution continuum theory is a higher order continuum theory where additional kinematic variables account for microstructural inhomogeneities at several distinct length scales. This can be particularly important for localization problems. The strength of this theory is that it can account for details in the microstructure of a material without using an extremely fine mesh. The present paper describes the implementation and verification of a 3D elastic–plastic multiresolution element based on an implicit time stepping algorithm. It is implemented in the general purpose finite element program FEAP. The mesh independency associated with the length scale parameter is examined and the convergence rate of the element is also evaluated.

  • 31.
    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.

  • 32.
    Wedberg, Dan
    et al.
    AB Sandvik Coromant, Metal Cutting Research.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modelling flow stress of AISI 316L at high strain rates2015In: Mechanics of materials (Print), ISSN 0167-6636, E-ISSN 1872-7743, Vol. 91, no 1, p. 194-207Article in journal (Refereed)
    Abstract [en]

    Modelling of the material behaviour is crucial for machining simulations. Strain and strain rates can reach values of 1–10 and 103–106 s−1 during the severe deformations associated with machining. An existing dislocation density model for AISI 316L based on a coupled set of evolution equations for dislocation density, mono vacancy concentration is enhanced in order to accommodate plastic deformation at high strain rates. Two mechanisms are evaluated with respect to their contribution in this respect. One is rate dependent cell formation and the other is dislocation drag due to phonons and electrons. Furthermore a temperature and strain rate dependent recovery and a proportionality interaction factor and short range component that both depends on the dislocation density are also considered. High strain rate compression tests are performed using Split-Hopkinson technique at various initial temperatures. Experimental results are then used to calibrate the models via an optimization procedure. Evaluation of various flow stress models shows that the flow stress behaviour of 316L stainless steel is best modelled by the model with a rate dependent cell formation. Its numerical solution is implemented in a format suitable for large-scale finite element simulations

  • 33.
    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

  • 34.
    Abiri, Olufunminiyi
    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.
    Non-local damage models in manufacturing simulations2015In: European journal of mechanics. A, Solids, ISSN 0997-7538, E-ISSN 1873-7285, Vol. 49, p. 548-560Article in journal (Refereed)
    Abstract [en]

    Localisation of deformation is a problem in several manufacturing processes. Machining is an exception where it is a wanted feature. However, it is always a problem in finite element modelling of these processes due to mesh sensitivity of the computed results. The remedy is to incorporate a length scale into the numerical formulations in order to achieve convergent solutions. Different simplifications in the implementation of a non-local damage model are evaluated with respect to temporal and spatial discretisation to show the effect of different approximations on accuracy and convergence.

  • 35.
    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

  • 36.
    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.

  • 37.
    Fisk, Martin
    et al.
    Materials Science and Applied Mathematics, Faculty of Technology and Society, Malmö University.
    Ion, John
    Division of Materials Science, Malmö University.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Flow stress model for IN718 accounting for evolution of strengthening precipitates during thermal treatment2014In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 82, p. 531-539Article in journal (Refereed)
    Abstract [en]

    A flow stress model describing precipitate hardening in the nickel based alloy Inconel® 718 following thermal treatment is presented. The interactions between precipitates and dislocations are included in a dislocation density based material model. Compression tests have been performed using solution annealed, fully-aged and half-aged material. Models were calibrated using data for solution annealed and fully-aged material, and validated using data from half-aged material. Agreement between experimental data and model predictions is good.

  • 38. Smith, Mike
    et al.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modeling of welding of austenitic stainless steels2014In: Encyclopedia of Thermal Stresses, Dordrecht: Encyclopedia of Global Archaeology/Springer Verlag, 2014, p. 3158-3165Chapter in book (Refereed)
  • 39.
    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.

  • 40.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Welding and heat treatment of alloys2014In: Encyclopedia of Thermal Stresses, Dordrecht: Encyclopedia of Global Archaeology/Springer Verlag, 2014, p. 6558-6567Chapter in book (Refereed)
  • 41.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Welding stresses2014In: Encyclopedia of Thermal Stresses, Dordrecht: Encyclopedia of Global Archaeology/Springer Verlag, 2014, p. 6594-6600Chapter in book (Refereed)
  • 42.
    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

  • 43.
    Babu, Bijish
    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.
    Dislocation density based model for plastic deformation and globularization of Ti-6Al-4V2013In: International journal of plasticity, ISSN 0749-6419, E-ISSN 1879-2154, Vol. 50, p. 94-108Article in journal (Refereed)
    Abstract [en]

    Although Ti-6Al-4V has numerous salient properties, its usage for certain applications is limited due to the challenges faced during manufacturing. Understanding the dominant deformation mechanisms and numerically modeling the process is the key to overcoming this hurdle. This paper investigates plastic deformation of the alloy at strain rates from 0.001s−1 to 1s−1 and temperatures between 20° C and 1100° C. Pertinent deformation mechanisms of the material when subjected to thermo-mechanical processing are discussed. A physically founded constitutive model based on the evolution of immobile dislocation density and excess vacancy concentration is developed. Parameters of the model are obtained by calibration using isothermal compression tests. This model is capable of describing plastic flow of the alloy in a wide range of temperature and strain rates by including the dominant deformation mechanisms like dislocation pile-up, dislocation glide, thermally activated dislocation climb, globularization, etc. The phenomena of flow softening and stress relaxation, crucial for the simulation of hot forming and heat treatment of Ti-6Al-4V, can also be accurately reproduced using this model.

  • 44.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Fisk, Martin
    Materials Science, Technology and Society, Malmö Högskola.
    Dislocation density based plasticity model coupled with precipitate model2013In: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 535 - 536, p. 125-128Article in journal (Refereed)
    Abstract [en]

    A dislocation density based plasticity model is applied to two variants of steels. One is an austenitic (fcc) stainless steel with ordered precipitates and the other is a Ti-Nb microalloyed (bcc) steel. Precipitate distributions are measured and this information is combined with appropriate precipitate hardening models. The flow stress model is also calibrated for an nickel-based superalloy where it is combined with a model for precipitate growth

  • 45.
    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.

  • 46.
    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.

  • 47.
    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.
    Liu, Wingkam
    Northwestern University, Evanston.
    Tang, Shan
    College of Material Science and Engineering, Chongqing University.
    Multiscale resolution continuum theory for elastic plastic material with damage, an implicit 3D implementation2013In: Computational Plasticity XII: Fundamentals and Applications - Proceedings of the 12th International Conference on Computational Plasticity - Fundamentals and Applications, COMPLAS 2013, Barcelona, 2013, p. 1448-1457Conference paper (Refereed)
    Abstract [en]

    The multiscale resolution continuum theory (MRCT) [1] is a higher order continuum theory in which additional kinematic variables are added to account for the size effect at several distinct length scales. This remedies the deficiency of the conventional continuum approach when predicting both strain softening and strain hardening materials and resolves the microstructure details without extremely fine mesh in the localization zone, however additional nodal degrees of freedom are needed and the requirement of element size at the length scale somewhat adds to the computational burden. This paper is an extension of the simplified 1D multiscale implementation presented in Complas XI 2011 [14]. A 3D elastic-plastic multiscale element, with one additional subscale in which the damage is applied, is implemented implicitly in the general purpose finite element analysis program FEAP.

  • 48.
    Abiri, Olufunminiyi
    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.
    Non-local damage models in manufacturing simulations2013Conference paper (Refereed)
    Abstract [en]

    Localisation of deformation is a problem in several manufacturing processes. Machining is an exception where it is a wanted feature. However, it is always a problem in finite element modelling of these processes due to mesh sensitivity of the computed results. The remedy is to incorporate a length scale into the numerical formulations in order to achieve convergent solutions. Different simplifications in the implementation of a non-local damage model are evaluated with respect to temporal and spatial discretisation to show the effect of different approximations on accuracy and convergence.

  • 49.
    Sandberg, Stefan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Lundin, Michael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Näsström, Mats
    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.
    Berglund, Daniel
    Gestamp Hardtech AB, Luleå.
    Supporting engineering decisions through contextual, model-oriented communication and knowledge-based engineering in simulation driven product development: an automotive case study2013In: Journal of engineering design (Print), ISSN 0954-4828, E-ISSN 1466-1837, Vol. 24, no 1, p. 45-63Article in journal (Refereed)
    Abstract [en]

    Modern manufacturers rely increasingly on overlapping activities and frequent, bilateral exchange of preliminary information, adding to the complexity of information exchange and general reuse. The approach presented in this paper relies on a reuse process, embedded in the design environment already used, to avoid disrupting the design process and to increase the foundation upon which decisions are made. The proposed approach relies on Knowledge Based Extensions to commercial CAE systems and 3D CAE models to enable and ensure Simulation Driven Design capabilities and contextual communication within the early stages of product development. The approach has been shown to increase the simulation-driven capabilities in a business-to-business scenario, and in extension, increase the foundation upon which decisions are made and the likelihood of reaching a feasible and optimal final design. In conclusion, a simulation-driven design approach to product development has to be more than enabled to truly make a difference in the development process. Investigation and evaluations show that supporting tools and relevant information must be made readily available, intuitive, integrated into the environment where they are needed and, ultimately, be perceived as a natural part of daily development in order for them to be accepted and used.

  • 50.
    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.

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