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  • 1.
    Hjertsen, David
    et al.
    Luleå tekniska universitet.
    Sjöström, Johnny
    Department of Materials Engineering, Karlstad University.
    Bergström, Jens
    Department of Materials Engineering, Karlstad University.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Finite element simulation of the tool steel stress response as used in a hot forging2004In: Materials Processing and Design: Modeling, Simulation and Applications (NUMIFORM 2004) / [ed] Somnath Ghosh, Melville, NY: American Institute of Physics (AIP), 2004, p. 560-565Conference paper (Refereed)
    Abstract [en]

    Hot-work forging tools are subjected to severe and complex loading conditions (cyclic stress/strain conditions, varying strain rates, varying temperature, environmental damage), leading to short die life. There is also a temperature and time dependant material response to consider. Presently, hot-forging of a steel crankshaft is approached by a combined experimental and numerical simulation study of a hot-work tool steel. The forging conditions were investigated by thermal measurements and damage analysis. Laboratory testing by isothermal fatigue in the temperature range 200 - 600DGC was performed. An elasto-plastic kinematic and isotropic hardening model (according to Chaboche) was used to model the material behaviour where the material parameters were derived from the experimental part. Viscoplastic effects are not accounted for in the material model as they have minor influence on the stress-strain relation in the experimental setup. The model was implemented in a FEM program (MSC.Marc) using a semi-implicit time integration scheme according to Shin and Ortiz, and evaluated by modelling of the isothermal fatigue tests. The FE-results managed to describe the materials general behavior, the correlation between the experimental simulated values were however not satisfactory due to influence of factors in the parameter derivation. Important features of the material behaviour are the cyclic softening and its dependence of the temperature, and also the strain path history. The long-term goal is to fully analyze the hot-forging die in service by numerical simulation and to study the influence of manufacturing processes on die properties.

  • 2. Jonsson, Mikael
    et al.
    Josefson, B.L.
    Division of Solid Mechanics, Chalmers University of Technology.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Experimentally determined deformations and stresses in narrow-gap and single-U multi-pass butt-welded pipes1993In: Journal of Offshore Mechanics and Arctic Engineering-Transactions of The Asme, ISSN 0892-7219, E-ISSN 1528-896X, Vol. 115, no 2, p. 116-122Article in journal (Refereed)
    Abstract [en]

    This paper describes a study of the multi-pass butt-welding of thick-walled pipes. Two different groove shapes were used: single-U and narrow-gap grooves. Strains were measured on both the pipe outer and inner surfaces during and after welding. Residual stresses and radial deflections were measured on the outer surface after welding. Measured parameters of the two different groove shapes are compared and discussed. Residual stresses at the weld center and radial deflections in the narrow-gap pipe were somewhat larger than those in the single-U pipe. The residual stress fields of both types of groove were found to be rotationally nonsymmetrical. The experimentally obtained residual stresses and radial deflections are compared with corresponding analytical and empirical results based on methods described in the literature and with numerical results for the same pipe from a separate study. Deviations between the measurements presented in this study and published results are discussed.

  • 3. Jonsson, Mikael
    et al.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Josefson, B. Lennart
    Chalmers University of Technology.
    Experimentally determined deformations and stresses in narrow gap and single-U multi-pass butt welded pipes1989Report (Other academic)
  • 4. Jonsson, Mikael
    et al.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Josefson, B.L.
    Experimentally determined deformations and stresses in narrow gap and single-U multi-pass butt-welded pipes1991In: Proceedings of the 10th International Conference on Offshore Mechanics and Arctic Engineering, 1991: presented at the 10th International Conference on Offshore Mechanics and Arctic Engineering, Stavanger, Norway, June 23-28, 1991 / [ed] Mamdouh M. Salama, New York: American Society of Mechanical Engineers , 1991, Vol. 3, p. 17-24Conference paper (Refereed)
    Abstract [en]

    Multi-pass butt-welding of thick walled pipes is studied. Two different groove shapes are used, single-U and narrow gap groove. Strains have been measured on both the pipe outer and inner surfaces during and after welding. Residual stresses and radial deflections have been measured on the outer surface after welding. The measured quantities are compared and discussed for the two different groove shapes. Residual stresses at the weld center and radial deflections were somewhat larger for the narrow gap groove. Furthermore, the residual stress fields for both grooves were found to be rotationally nonsymmetric. The experimentally obtained residual stresses and radial deflections are compared with corresponding analytical and empirical results based on methods from the literature and with numerical results for the same pipe from a separate study. Deviations between the measurements (on OX524D) and the results from the literature are discussed.

  • 5.
    Karlberg, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Martin
    Karlsson, Lennart
    Näsström, Mats
    Dynamics of rotor systems with clearance and weak pedestals in full contact2010In: 13th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery 2010 (ISROMAC-13): Honolulu, Hawaii, USA, 4 - 7 April 2010, Red Hook, NY: Curran Associates, Inc., 2010, p. 531-536Conference paper (Refereed)
    Abstract [en]

    Many rotating machineries are supported by bearings with clearance, which are further clamped in, compared to the bearing stiffness, weak pedestals. As have been reported in several studies, it is essential to choose a proper clearance in order to avoid unwanted vibrations. When rotating machineries supported by bearings with clearance are subjected to stationary loads (gravity, magnetic pull etc.), it may not loose contact between the shaft and the bearing (i.e. full contact). However, even in full contact unwanted dynamics can occur which is of interest in this paper. It is found that the clearance give raise to anisotropic pedestal stiffness. It is further shown that some of the resonance frequencies decrease with the clearance.

  • 6.
    Karlsson, Lennart
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Jonsson, Mikael
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Trovie, L.
    Residual stresses and deformations in a welded thin-walled pipe1989In: Weld residual stresses and plastic deformation: papers / [ed] E. Rybicki; M. Shiratori, New York: American Society of Mechanical Engineers , 1989Conference paper (Refereed)
    Abstract [en]

    Deformations and stresses during butt-welding of a pipe are calculated as well as the residual deformations and stresses. The temperature field during welding is calculated using an analytical solution. The deformations and stresses are calculated by use of the finite element method. A thermo-elastoplastic material model is used. Special attention is paid to the influence of the volume changes due to phase transformations on the deformations (radial shrinkage) and the residual stresses. The calculated radial shrinkage and residual stresses are compared to experimental values. Good agreement was obtained.

  • 7.
    Karlsson, Lennart
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Ökvist, M.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Design of die and its effect on wear in cup forming1995In: Simulation of materials processing: theory, methods and applications : proceedings of the fifth international conference on numerical methods in industrial forming processes, Ithaca, New York, USA, 18 - 21 June 1995 / NUMIFORM '95 / [ed] Shan-Fu Shen; Paul R Dawson, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1995, p. 587-591Conference paper (Refereed)
  • 8.
    Lejon, Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lundin, Michael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Dagman, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Jeppsson, Peter
    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.
    Integrated Capture and Representation of Product Information In Computer-Aided Product Development2015In: ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference: August 2-5, 2015, Boston, Massachusetts, USA., New York: American Society of Mechanical Engineers , 2015, Vol. 1B, article id DETC2015-47299Conference paper (Refereed)
    Abstract [en]

    This paper features the implementation and evaluation of a proposed approach for information capture and representation integrated into the existing design environments at two manufacturing companies. A tool has been developed that automatically derives information from the CAD system during design and provides users with the means to capture product information that has previously been documented outside of the CAD system. Product information is managed in a PLM data model and becomes, once stored, the foundation for providing tailored views of information.Feedback from the evaluation shows that the prescribed approach was preferred to the current one and that it would likely provide value to users, both authors and consumers, of product information. This approach can reduce the time required to capture the pertinent product information. However, the primary savings are likely to be indirect as a result of increased consistency, understanding, and the potential (re)use of product information.The approach and tools presented constitute another step toward providing each stakeholder with more efficient, intuitive, contextual, and purposeful support for information capture and representation in computer-aided product development.

  • 9.
    Lejon, Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lundin, Michael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Jeppsson, Peter
    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.
    Integrating information in product development2013In: Re-engineering Manufacturing for Sustainability: Proceedings of the 20th CIRP International Conference on Life Cycle Engineering, Singapore 17-19 April, 2013 / [ed] Andrew Y. C. Nee; Bin Song; Soh-Khim Ong, Singapore: Springer Singapore , 2013, p. 93-98Conference paper (Refereed)
    Abstract [en]

    The amount of product and process related information in the engineering industry is large and constantly growing. Methods and tools are therefore needed to effectively leverage the information, ensuring that it is readily available, contextually understandable and usable for the activity at hand. This paper presents findings from two cases performed at manufacturing companies and an approach for how information effectively can be utilized during the development and lifecycle of a product. The approach primarily addresses the lack of up-to-date information, free of redundancies and accessible from the context where it is needed or will be captured.

  • 10. Lindbäck, Torbjörn
    et al.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Residual stresses in railway rails after manufacturing2001In: Simulation of materials processing: theory, methods and applications : proceedings of the 7th International conference on numerical methods in industrial forming processes - NUMIFORM 2001 / [ed] Ken-ichiro Mori, Lisse: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 2001, p. 573-6Conference paper (Refereed)
  • 11.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Runnemalm, Henrik
    Luleå tekniska universitet.
    Hedblom, Erika
    Luleå tekniska universitet.
    Seok-Jeong, Hyun
    Developments in finite element techniques for facilitating the simulation of welding in industrial applications2001In: Mathematical modelling of weld phenomena 5: [the Fifth International Seminar on the 'Numerical Analysis of Weldability' was held in September 1999 at its usual location in Schloss Seggau near Graz, Austria] / [ed] H. Cerjak, London: Institute of Materials , 2001, p. 743-753Conference paper (Refereed)
    Abstract [en]

    Using the examples of EB welding of a copper canister (for spent nuclear fuel storage) and multirun submerged arc welding of thick steel plates, the finite element (FE) methods (2D and 3D models) developed to simulate such industrial welding applications are examined. With respect to multirun welding, challenges imposed by addition of filler material, history dependency of the material and computer resources are considered. The FE developments discussed include combined shell and solid elements, adaptive meshing, techniques for extending the FE model, and computing phase changes/material properties for low alloy steels.

  • 12.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Runnemalm, Henrik
    Luleå tekniska universitet.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Simulation of multipass welding of a thick plate1999In: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 44, no 9, p. 1301-1316Article in journal (Refereed)
    Abstract [en]

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

  • 13.
    Lundin, Michael
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lejon, Erik
    Gestamp RandD.
    Dagman, Andreas
    Product and Production Development, Chalmers University of Technology.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Efficient design module capture and representation for product family reuse2017In: Journal of Computing and Information Science in Engineering, ISSN 1530-9827, E-ISSN 1944-7078, Vol. 17, no 3, article id 031002Article in journal (Refereed)
    Abstract [en]

    New business models and more integrated product development processes require designers to make use of knowledge more efficiently. Capture and reuse are means of coping, but support, techniques, and mechanisms have yet to be sufficiently addressed. This paper consequently explores how computer-aided technologies (CAx) and a computer-aided design (CAD) model-oriented approach can be used to improve the efficiency of design module capture and representation for product family reuse. The first contribution of this paper is the investigation performed at a Swedish manufacturing company and a set of identified challenges related to design capture and representation for reuse in product family development. The second contribution is a demonstrated and evaluated set of systems and tools, which exemplifies how these challenges can be approached. Efficient design capture is achieved by a combination of automated and simplified design capture, derived from the design implementation (CAD model definition) to the extent possible. Different design representations can then be accessed by the designer using the CAD-internal tool interface. A web application is an example of more generalpurpose representation to tailor design content, all of which is managed by a product lifecycle management (PLM) system. Design capture is based on a modular view block definition, stored in formal information models, management by a PLM system, for consistent and reliable design content. It was, however, introduced to support the rich and expressive forms of capture and representation required to facilitate understanding, use, and reuse of varied and increasingly complex designs. A key element in being able to describe a complex design and its implementation has been capture and representation of a set of design states. The solution has been demonstrated to effectively be able to capture and represent significant portions of a step-by-step design training material and the implementation of complex design module through a set of design decisions taken. The validity and relevance of the proposed solution is strengthened by the level of acceptance and perceived value from experienced users, together with the fact that the company is implementing parts of it today

  • 14.
    Lundin, Michael
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lejon, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Dagman, Andreas
    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.
    Jeppsson, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    An Empirical Study Of Information Exchange And Design Support In Product Family Development2014In: Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, New York: American Society of Mechanical Engineers , 2014, article id DETC2014-34940Conference paper (Refereed)
  • 15.
    Lundin, Michael
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Sandberg, Stefan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Knowledge retention and reuse: using CAD models as carriers of knowledge in product development2010In: Proceedings of the ASME 2010 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference: presented at ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, August 15 - 18, 2010, Montreal, Quebec, Canada, New York: American Society of Mechanical Engineers , 2010, Vol. 3 : 30th Computers and Information in Engineering Conference, Parts A and B, p. 1173-1182Conference paper (Refereed)
    Abstract [en]

    In order to ensure competitive advantage, manufacturers need to reduce the time and resources spent on development without affecting the quality and performance of the final product. Studies show that designers are likely to change both job and company several times during their career. The loss of experience and expertise implies that new methods for efficient knowledge retention and reuse need to be developed. Results presented in this paper include development and implementation of a previously proposed method suggesting the use of CAD models as carriers of knowledge. The method has been further developed and realised in a three-part demonstrator, each part addressing one aspect of a holistic approach to efficient knowledge retention and reuse. The approach presented here does not require the use of any additional applications during product development and it ensures that the designer has access to necessary information, where and when it is needed. This approach also results in less time spent on documentation, data conversion and information retrieval.

  • 16.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Experimental verification of numerically determined residual deformations and stresses in welding1989Licentiate thesis, comprehensive summary (Other academic)
  • 17.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Thermo-mechanical modelling of welding with experimental verification1992Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Residual stresses and deformations after welding were studied numerically and experimentally. The numerical simulations were performed using the finite element method. In the calculations a thermoelastoplastic material model was used. This means that temperature dependence of material properties and volume changes due to phase transformations were considered. Different finite element models of welded structures were investigated. In these models brick elements, shell elements, plane elements and a combination of brick elements and shell elements were used. The results achieved in the finite element simulations were evaluated by experimental measurements. The neutron diffraction technique and the hole-drilling strain gauge method were utilized for the determination of residual stresses. Also transient measurements of strains were performed. The residual diametrical shrinkage after circumferential welding of a pipe was measured and compared to calculated results.

  • 18.
    Näsström, Mats
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Welding heat input models2014In: Encyclopedia of Thermal Stresses, Dordrecht: Encyclopedia of Global Archaeology/Springer Verlag, 2014, p. 6567-6572Chapter in book (Refereed)
  • 19.
    Näsström, Mats
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lundström, Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Turesson, Lena
    Luleå University of Technology, Professional Support, VSS TVM.
    Palmblad, Marie-Louise
    Luleå University of Technology, Professional Support, VSS TVM.
    Projekt: Fastelaboratoriet - VINNEXC2007Other (Other (popular science, discussion, etc.))
    Abstract [sv]

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

  • 20.
    Näsström, Mats
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Wang, J.
    Webster, P.
    Residual stresses and deformations due to longitudinal welding of pipes1993In: International trends in welding science and technology: 3rd International conference on trends in welding research : Papers / [ed] Stan A. David; J.M. Vitek, Materials Park, Ohio: ASM International, 1993, p. 109-115Conference paper (Refereed)
    Abstract [en]

    Results of finite element calculations and neutron diffraction measurements of residual stress distributions in a component welded from hollow square section inconel tubes are presented. In the finite element analysis, plane deformation conditions were assumed. The material is assumed to be thermoelastic--plastic with temperature dependent material properties. The mechanical field is coupled to the temperature field only through the temperature dependent constitutive properties and the thermal strain. The plane deformation formulation differs from the ordinary plane strain formulation only in the nodal displacement-strain relationship. This difference is that epsilon 33instead of being zero is computed from the equation epsilon 33 = beta sub 1 + beta sub 2 x sub 1 + B sub 3x2 where beta sub 1 , beta sub 2 and beta sub 3 are constants. These constants add three unknowns to the system of equations in the FE-analysis. To validate the calculations, the computed strains are compared with measured strains. The measurements were made at ten points between two of the welds in three orthogonal directions, using the neutron diffraction technique. The neutron technique differs from the X-ray diffraction method in that neutrons can penetrate substantial distances into the interiors of components which X-rays cannot. This penetration makes it possible to measure through thickness strain variations. In the results one can see that this plane deformation analysis predicts the actual strains and stresses much better than the plane strain analysis. Comparison between these plane deformation results and earlier results from a three-dimensional analysis is also done.

  • 21.
    Näsström, Mats
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Wikander, L.
    Luleå tekniska universitet.
    Karlsson, Lennart
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Goldak, J.
    Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa.
    Combined solid and shell element modelling of welding1992In: Mechanical effects of welding: IUTAM symposium, Luleå/Sweden, June 10-14, 1991 / [ed] Lennart Karlsson, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 1992, p. 197-206Conference paper (Refereed)
    Abstract [en]

    Finite element calculations of residual stress distribution in a welded component from a hollow square section Inconel 600 tube are presented. Shell element can be successfully used in finite element calculations of thin walled structures. However, in the weld and the heat affected zone (HAZ) shell elements may not be sufficient, since the through thickness stress gradient is high in these regions. A combination of eight-nodes solid elements and four-nodes shell elements is used. The solid elements are used in and near the weld and shell elements are used elsewhere. This combination of solid elements and shell elements reduces the number of degrees of freedom in the problem in comparison with the use of solid elements only

  • 22. Pahkamaa, Andreas
    et al.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Pavasson, Jonas
    Karlberg, Magnus
    Näsström, Mats
    Goldak, John
    Carleton University, Ottawa.
    A method to improve efficiency in welding simulations for simulaton driven design2010In: Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference - 2010: presented at ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, August 15 - 18, 2010, Montreal, Quebec, Canada, New York: American Society of Mechanical Engineers , 2010, p. 1-10Conference paper (Refereed)
    Abstract [en]

    Welding is one of the most commonly used methods of joining metal pieces. In product development it is often desirable to predict residual stresses and distortions to verify that e.g., alignment tolerances, strength demands, fatigue requirements, stress corrosion cracking, etc. are fulfilled. The objective of this paper is to derive a strategy to improve the efficiency of welding simulations aiming at a (future) simulation-driven design methodology. In this paper, a weld bead deposition technique called block dumping has been applied to improve the efficiency. The proposed strategy is divided into seven steps, where the first four steps are verified by two welding simulation cases (a benchmark problem for a single weld bead-on-plate specimen and a T-welded structure). This study shows that by use of the block dumping technique, the computation time can be reduced by as much as 93% compared to moving heat source, still with acceptable accuracy of the model.

  • 23.
    Ringsberg, Jonas W.
    et al.
    Luleå tekniska universitet.
    Lindbäck, Torbjörn
    Olsson, M.
    Luleå tekniska universitet.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Rail rolling contact fatigue caused by heavy haul train transports in cold climates2000Report (Other academic)
    Abstract [en]

    In this report an investigation of contact fatigue in railway track is presented. Especially rolling contact fatigue under enviromental extremes such as heavy load will be studied. The focus is on the modelling of the processes that lead to contact fatigue. In order to model this process the residual stress state after manufacturing will be taken into account. In this study Luleå university of technology has modelled the manufacturing process which includes calculating residual stresses after manufacturing. Chalmers University of Technology has analysed the fatigue life of the rail due to rolling contact fatigue. Three different load cases have been considered; one with stress free initial conditions, one with measured residual stress values and one with residual stress values calculated from the modelling of the manufacturing process. The simulation shows that crack initiation will appear after 1-2 days of heavy haul traffic, which agree with informations from Banverket that states that cracks have been observed after less than one week.

  • 24.
    Runnemalm, Henrik
    et al.
    Luleå tekniska universitet.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lampa, Conny
    Accuracy in thermal analysis of laser1995In: Computational methods and experimental measurements VII / [ed] G.M. Carlomagno; C.A. Brebbia, Southampton: WIT Press, 1995, p. 85-92Conference paper (Refereed)
    Abstract [en]

    The paper focuses on the problem of obtaining accurate thermal fields despite the uncertainty of the thermal heat input and thermal properties at high temperatures. The net heat input is the primary factor for obtaining an accurate temperature field. A good correlation between simulations and experiments is obtained. The net heat input during laser welding a bead on a thin plate made of austenitic stainless steel is determined using a water calorimeter. Transient temperature is measured by thermocouples. The FEM is used in the numerical simulation of the process

  • 25.
    Sandberg, Marcus
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Larsson, Tobias
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Åström, Peter
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    A design tool integrating CAD and virtual manufacturing for distortion assessment2005In: 15th International Conference on Engineering Design - ICED 05: 15 - 28 August 2005 / [ed] Andrew Samuel; William Lewis, Barton: Institution of Engineers, Australia , 2005Conference paper (Refereed)
    Abstract [en]

    In the aero space industry, design for manufacturing promotes machining predictions using finite element analysis during design. Today design and computational engineers often are far from integrated. The design tool in this paper couples the simulation of distortion effects due to machining with CAD, where knowledge of how to perform a machining simulation is captured within the tool. The tool system is governed by a UNIX shell script and uses Python scripts for pre- and post-processing purposes coupled to the finite element software MSC.MarcTM. The tool allows an engineer to estimate the distortion effects due to machining and is believed to help bridge the gap between design and computational engineers in the manufacturing planning stages of engineering design. By using tools like the one presented here, both component quality and accuracy of machining operation cost estimation can be expected to increase, since distortion problems can be solved or prevented already in the manufacturing planning stages of engineering design. Thus design for manufacturing is enhanced since redesign due to inferior manufacturing can be reduced.

  • 26.
    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.

  • 27.
    Sandberg, Stefan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    A new method to preserve knowledge and information by use of knowledge enabled engineering2008In: Proceedings of the 27th Computers and Information in Engineering Conference (CIE)IDETC/CIE 2007: September 4-7, 2007, Las Vegas, Nevada, USA, American Society of Mechanical Engineers , 2008Conference paper (Refereed)
    Abstract [en]

    Today's automotive industry produces more new car models in a shorter time than ever before. Every car model comes in many different versions regarding number of doors, engine, transmission etc while being built on a platform strategy. This leads to a lot of different knowledge and information that needs to be tracked for the different components in addition to other information e.g. what function does design features have, why is this radius not smaller etc. Volvo Car Corporation (VCC) is in need of an effective method to save and present all this knowledge and information today. This paper describes a new method, to gather and save knowledge and information about car body parts also called body-inwhite, which was implemented in a demonstrator and tested and evaluated on VCC.

  • 28. Sandberg, Stefan
    et al.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    A proposed method to preserve knowledge and information by use of knowledge enabled engineering2008In: Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference - 2007: presented at 2007 ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, September 4 - 7, 2007, Las Vegas, Nevada, USA, New York: American Society of Mechanical Engineers , 2008, Vol. 2, PART A, p. 207-212Conference paper (Refereed)
    Abstract [en]

    Today's automotive industry produces more new car models in a shorter time than ever before. Every car model comes in many different versions regarding number of doors, engine, transmission etc while being built on a platform strategy. This leads to a lot of different knowledge and information that needs to be tracked for the different components in addition to other information e.g. what function does design features have, why is this radius not smaller etc. Volvo Car Corporation (VCC) is in need of an effective method to save and present all this knowledge and information today. This paper describes a new method, to gather and save knowledge and information about car body parts also called body-in white, which was implemented in a demonstrator and tested and evaluated on VCC.

  • 29.
    Svoboda, Ales
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Häggblad, Hans-åke
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Simulation of hot isostatic pressing of metal powder components to near net shape1996In: Engineering computations, ISSN 0264-4401, E-ISSN 1758-7077, Vol. 13, no 5, p. 13-37Article in journal (Refereed)
    Abstract [en]

    Presents a finite element formulation of hot isostatic pressing (HIP) based on a continuum approach using thermal-elastoviscoplastic constitutive equations with compressibility. The formulation takes into consideration dependence of the viscoplastic part on the porosity. Also takes into account the thermomechanical response, including nonlinear effects in both the thermal and mechanical analyses. Implements the material model in an implicit finite element code. Presents experimental procedures for evaluating the inelastic behaviour of metal powders during densification and experimental data. Chooses the simulation of the dilatometer measurement of a cylindrical component during HIP and manufacturing simulation of a turbine component to near net shape (NNS) as a demonstrator example. Both components are made of a hot isostatically pressed hot-working martensitic steel. Compares the result of the simulation in the form of the final geometry of the container with the geometry of a real component produced by HIP. Makes a comparison between the calculated and measured deformations during the HIP process for the cylindrical component. Measures the final geometry of the turbine component by means of a computer controlled measuring machine (CMM). Performs the complete process from design and simulation to geometry verification within a computer-aided concurrent engineering (CACE) system

  • 30. Troive, Lars
    et al.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Näsström, Mats
    Webster, P.
    Low, K.S.
    Finite element simulation of the bending of a flat plate to U-shaped beam cross-section and neutron diffraction determination of residual stresses1990In: Recent trends in welding science and technology: TWR '89 proceedings / [ed] Stan A. David; J.M. Vitek, Materials Park, Ohio: ASM International, 1990, p. 107-111Conference paper (Refereed)
    Abstract [en]

    Results of strains from finite element calculations and measurements by the neutron diffraction method in a hollow welded steel beam profile are presented. To calculate the residual strains, each step in the manufacturing process has to be simulated. The D-shaped beam profile is built up by a plate which is flanged into a U-cross-section profile and then welded together with a plate on the top edges. The finite element analysis includes simulation of the manufacturing of the cross-section by bending where large deformations are accounted for. Then, the finite element simulation of the welding pass follows. Plane strain conditions were assumed. The material was assumed to be thermoelastic--plastic, with temperature dependent mechanical material properties. To verify the calculations, measurements of strain were made at approx 40 points, in three orthogonal directions, using the neutron diffraction method. The neutron technique differs from the established X-ray diffraction in the way that the neutrons can penetrate substantial distances into the interior of components which the X-ray cannot. Graphs. 9 ref.-

  • 31.
    Troive, Lars
    et al.
    Luleå tekniska universitet.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Näsström, Mats
    Webster, Peter
    University of Salford, Department of Civil Engineering.
    Low, Keng S.
    University of Salford, Department of Civil Engineering.
    Finite element simulations of the bending of a flat plate to u-shaped beam cross-section and the welding to rectungular hollow cross-section and neutron diffraction determination of residual stresses1990In: Recent trends in welding science and technology: TWR '89 proceedings / [ed] Stan A. David; J.M. Vitek, Materials Park, Ohio: ASM International, 1990, p. 107-111Conference paper (Refereed)
    Abstract [en]

    Results of strains from finite element calculations and measurements by the neutron diffraction method in a hollow welded steel beam profile are presented. To calculate the residual strains, each step in the manufacturing process has to be simulated. The D-shaped beam profile is built up by a plate which is flanged into a U-cross-section profile and then welded together with a plate on the top edges. The finite element analysis includes simulation of the manufacturing of the cross-section by bending where large deformations are accounted for. Then, the finite element simulation of the welding pass follows. Plane strain conditions were assumed. The material was assumed to be thermoelastic--plastic, with temperature dependent mechanical material properties. To verify the calculations, measurements of strain were made at approx 40 points, in three orthogonal directions, using the neutron diffraction method. The neutron technique differs from the established X-ray diffraction in the way that the neutrons can penetrate substantial distances into the interior of components which the X-ray cannot.

  • 32.
    Troive, Lars
    et al.
    Mitthögskolan.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Jonsson, Mikael
    Experimental and numerical study of multi-pass welding process of pipe-flange joints1998In: Journal of Pressure Vessel Technology-Transactions of the ASME, ISSN 0094-9930, E-ISSN 1528-8978, Vol. 120, no 3, p. 244-251Article in journal (Refereed)
    Abstract [en]

    Residual deformations of pipe-flange joints due to thermal strains caused by the multi-pass welding procedure in a manufacturing process are investigated both experimentally and numerically (FEM). To avoid any risk of leakage between two mounted pipes using flange joints, geometrical distortions (twisting) of the flange must be prevented. How the flange is distorted depends both on the groove shape and the weld sequence used However, to be spared from machine work after the welding process, the distortions have to be minimized. A casting-technique has been developed in order to measure the twisting of the flange after each weld pass. Also, measurements of the residual radial deflection of the pipe have been performed.

  • 33. Wikander, Lars
    et al.
    Karlsson, Lennart
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Thermomechanical FE plane models of welding1993In: Modeling of casting, welding, and advanced solidification processes VI: proceedings of the Sixth Conference in a series on Modeling, Casting, and Welding Processes, held in Palm Coast, Florida, March 21-26, 1993 / [ed] T.S. Piwonka; Vaughan R. Voller; L. Katgerman, Warrendale, Pa: Minerals, Metals & Materials Society, 1993, p. 553-560Conference paper (Refereed)
    Abstract [en]

    Finite element simulations of welding were devised for a welded beam with a D shaped cross section. Finite element computations incorporating temperature dependant materials properties and the stresses resulting from bending the plate were compared with measurements of residual strains and stresses measured using neutron diffraction. The beam was constructed of Swedish type 142132 structural steel 6 mm in thickness, GMA welded down both sides of the beam simultaneously

  • 34.
    Wikander, Lars
    et al.
    Luleå tekniska universitet.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Näsström, Mats
    Webster, Peter
    Finite element simulation and measurement of welding residual stresses1994In: Modelling and Simulation in Materials Science and Engineering, ISSN 0965-0393, E-ISSN 1361-651X, Vol. 2, no 4, p. 845-864Article in journal (Refereed)
    Abstract [en]

    Residual strains and stresses in a hollow steel beam that had been welded to a D-shaped cross-section have been simulated by plane deformation finite element models and compared with experimental measurements obtained using the neutron diffraction strain-scanning technique. Neutron strain scanning, in contrast to other experimental techniques, is capable of measuring, accurately, non-destructively and in detail, the internal strain state at selected locations and directions within a component. This makes it a preferred method for validating model calculations of strain and stress distributions in components. In the finite element simulations a plane deformation model incorporating temperature-dependent material properties was adopted. With the assumptions for material properties that were made, the plane deformation model predicts the overall bending of the beam and the overall residual strains and stresses reasonably well. Locally, in the weld metal the predicted residual strains and stresses depend very much on the values of the thermal strain, which in one simulation include volume changes due to solid-state phase transformations. In the other simulation presented here the volume changes due to solid-state phase transformations were not accounted for.

  • 35. Åström, Peter
    et al.
    Näsström, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Friction model parameter optimization for friction welding simulation of Ti-62462006In: Trends in welding research: proceedings of the 7th international conference : May 16-20, 2005, Callaway Gardens Resort, Pine Mountain, Georgia, USA / [ed] Stan A. David, Materials Park, Ohio: ASM International, 2006, p. 849-854Conference paper (Refereed)
    Abstract [en]

    With regard to the rotary friction welding process as used for joining of large rotationally symmetric structures in the aerospace industry, the finite element software "MSC. Marc" coupled with the optimisation code INVSYS was used to simulate the friction welding of two cylindrical titanium alloy Ti 6246 specimens while optimising parameters in the friction model. The friction model took into account the friction coefficient variation as a function of normal pressure in the contact, temperature and relative sliding velocity. The unconstrained subspace searching simplex method was employed for optimisation. An objective function was formulated to minimise the error between calculated and measured torques, and a parameter set was identified that produced better flash geometry agreement with experiment.

1 - 35 of 35
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