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  • 1. Andersson, Mikael
    et al.
    Jonsson, Mikael
    Söderlund, Anders
    Luleå University of Technology, Department of Arts, Communication and Education, Education, Language, and Teaching.
    The Greenhouse learning concept: a new pedagogical approach2002In: The Renaissance engineer of tomorrow: proceedings of the 30th SEFI annual conference, 2002Conference paper (Refereed)
  • 2.
    Benckert, Lars
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Jonsson, Mikael
    Molin, Nils-Erik
    Measuring 3-D displacement of a surface using the white light speckle technique1986In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, p. 207-210Article in journal (Refereed)
    Abstract [en]

    When measuring in plane surface deformation using white light speckle photography, errors will arise if an out of plane displacement is present. Here it is shown that stereoscopic photography resolves this problem and makes the measurement of true in plane displacements possible. A rigid body translation is also introduced to determine unambiguously the direction of the displacement

  • 3.
    Benckert, Lars
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Jonsson, Mikael
    Molin, Nils-Erik
    Measuring true in-plane displacements of a surface by stereoscopic white-light speckle photography1987In: Optical Engineering: The Journal of SPIE, ISSN 0091-3286, E-ISSN 1560-2303, Vol. 26, no 2, p. 167-169Article in journal (Refereed)
    Abstract [en]

    When in-plane surface deformations are measured using white-light speckle photography, errors arise if an out-of-plane displacement is present. Stereoscopic photography resolves this problem and makes possible the measurement of true in-plane displacements. A rigid-body translation is introduced to determine unambiguously the direction of the displacement

  • 4. Fällström, Karl-Evert
    et al.
    Jonsson, Mikael
    A nondestructive method to determine material properties in anisotropic plates1991In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 12, no 5, p. 293-305Article in journal (Refereed)
    Abstract [en]

    Material parameters in anisotropic rectangular plates are determined in a nondestructive way. Real-time, TV-holography is used to determine frequencies and shapes of the first five modes of vibration of plates with free-free boundary conditions. According to rules given in the paper, finite element analysis is then used to determine two effective Young's moduli, the shear modulus, and the Poisson's ratio

  • 5. Jonsson, Mikael
    Experimental and numerical study of deformations and stresses in butt-welded plates1986Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Deformations and stresses in butt-welding of plates are studied. Temperatures, strains, residual stresses and change in gap width in front of the heat source are calculated and measured. In particular, the change in gap width in front of the heat source during welding and residual stresses after welding are studied. The change in gap width is of interest in automatic welding production, and the residual stresses are of importance in design of welded structures. The sensitivity for variation of the values of the material properties, plate width, welding speed and heat input are investigated. Also the influence of the tack-welding procedure is analysed. The finite element method is used in the numerical simulations. Temperature dependence of the material properties and phase transformations are considered. A thermoelastoplastic material model is used and plane stress conditions are assumed. Good agreements between calculated and measured values of the studied quantities are obtained. The risk for hot cracking is numerically studied. Low welding speed and high heat input increases the risk for hot cracks to occur. A method to measure residual deformations is presented. The white light speckle technique is used to record the released residual deformations. The method is destructive. Experiments are performed and compared with corresponding calculated values.

  • 6. Jonsson, Mikael
    Simulation of dynamical behaviour of a front wheel suspension1991In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 20, no 5, p. 269-281Article in journal (Refereed)
    Abstract [en]

    A MacPherson front wheel suspension and its components are modelled with the finite element method. Nonlinearities due to both the geometry and the characteristics of the components (springs, dampers and bushings) are considered. The force due to a given compression/elongation of the spring strut is calculated and compared with experimental results. Kinematical results, change in track width and camber angle, are also shown and compared with experimental results. Good agreement between numerical and experimental results is obtained.

  • 7. Jonsson, Mikael
    et al.
    Benckert, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Measurements of residual deformations in butt-welded plates by use of the white light speckle technique1986In: Journal of Strain Analysis for Engineering Design, ISSN 0309-3247, E-ISSN 2041-3130, Vol. 21, no 4, p. 243-246Article in journal (Refereed)
    Abstract [en]

    A method to measure residual deformation in welded plates is presented. An optical technique, called white light speckle, is used to record the released residual deformations. The method is destructive. Two experiments have been performed. The results are compared with corresponding calculated values. A short description of the calculations is given

  • 8. Jonsson, Mikael
    et al.
    Josefson, B. Lennart
    Chalmers University of Technology.
    Experimentally determined transient and residual-stresses in a butt-welded pipe1988In: Journal of Strain Analysis for Engineering Design, ISSN 0309-3247, E-ISSN 2041-3130, Vol. 23, no 1, p. 25-31Article in journal (Refereed)
    Abstract [en]

    Single pass butt-welding of a pipe was studied. Low heat input was used to obtain a high cooling rate with adherent martensite in the final phase transformation in the heat affected zone. Strains and stresses were measured during and after welding on the pipe outer surface. Deviations from rotationally symmetric strain and stress fields in the pipe were studied. Two different analytical solutions for the residual stress field from the literature are discussed. The experimentally obtained residual stresses are compared with those analytical solutions. Qualitatively good agreement between experiments and analytical solutions was obtained, although the analytical solutions do not consider effects of phase transformations. The pipe was made of SIS2172 C--Mn steel

  • 9. 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.

  • 10. Jonsson, Mikael
    et al.
    Karlsson, Lennart
    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.
    Deformation and stresses in butt-welding of large plates1985In: Numerical methods in heat transfer: expanded and edited versions of selected papers from an international conference held in Swansea, July 1979 / [ed] R.W. Lewis; K. Morgan, John Wiley & Sons, 1985, Vol. 3, p. 35-57Conference paper (Refereed)
  • 11. Jonsson, Mikael
    et al.
    Karlsson, Lennart
    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.
    Deformations and stresses in butt-welding of large plates with special reference to the mechanical material properties1985In: Journal of engineering materials and technology, ISSN 0094-4289, E-ISSN 1528-8889, Vol. 107, no 4, p. 265-270Article in journal (Refereed)
    Abstract [en]

    Simulation of automatic butt-welding of large plates was investigated. Two different steels were considered. The plates were tack-welded before the butt-welding. The simulation includes the tack-welding, the butt-welding and the cooling to room temperature. The simulations should lead to an understanding of the mechanics behind the change in gap width in front of the moving arc, which is of importance in automatic welding production. The residual stresses due to the butt-welding were also studied. The magnitude and the distribution of the residual stress are important in design of welded structures.

  • 12. Jonsson, Mikael
    et al.
    Karlsson, Lennart
    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.
    Kan svetsegenspänningar och svetsdeformationer förutsägas?1986In: Svetsen, ISSN 0039-7091, Vol. 45, no 5, p. 6-9Article in journal (Other academic)
    Abstract [en]

    Many difficulties in welding result from the fact that heat input causes uneven heating of the welded object. This article reports on the results of an investigation carried out with the object to find out whether it is possible to predict residual stresses in welding and weld deformations with the aid of new computational methods used in continum mechanics. Butt welding of flat plates was studied in this investigation. Deformations, residual stresses, and gap width variations during the welding process were calculated.

  • 13. Jonsson, Mikael
    et al.
    Karlsson, Lennart
    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.
    Plate motion and thermal stresses in root-bead butt-welding and one-pass butt-welding of two different steels1984Conference paper (Other academic)
  • 14. Jonsson, Mikael
    et al.
    Karlsson, Lennart
    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.
    Plate motion and thermal stresses in root-bead butt-welding of plates1985In: Numerical methods in thermal problems: proceedings of the fourth international conference held in Swansea, UK on 15th - 18th July, 1985 / [ed] R.W. Lewis, Swansea: Pineridge Press , 1985, p. 1092-1102Conference paper (Refereed)
    Abstract [en]

    In this paper root-bead welding of plates of two different sizes was experimentally and theoretically analysed. The material of the plates was a fine-grain steel with yield limit 360 MPa. The finite element method was used for both the thermal analyses and the mechanical analyses. Temperature-dependent material properties and volume changes due to phase transformations were considered. Plane stress conditions were assumed. Good agreement between calculated and measured values were obtained.

  • 15. Jonsson, Mikael
    et al.
    Karlsson, Lennart
    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.
    Plate motion in butt-welding of tack-welded plates1984In: Numerical methods for transient and coupled problems: proceedings of an International Conference held in Venice, Italy on July 9th-13th, 1984 / [ed] R. W. Lewis; P. Bettess; E. Hinton; B.A. Schreffler, Swansea: Pineridge Press , 1984, p. 351-359Conference paper (Refereed)
  • 16. Jonsson, Mikael
    et al.
    Karlsson, Lennart
    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.
    Simulation of tack welding procedures in butt joint welding of plates1985In: Welding Journal, ISSN 0043-2296, Vol. 64, no 10, p. 296-301Article in journal (Refereed)
    Abstract [en]

    The influence of tack welding procedure on change in root opening was investigated. This change during the first part of welding depends on the order in which the tack welds are made. It is also affected by the starting position of the welding arc. These effects were studied in seven theoretical analyses - three cases where the tack welding procedures differed and four cases where the temperature fields at the beginning of the butt joint welding differed. The material investigated was a fine-grain steel with a yield stress of 360 MPa (52,200 psi) at room temperature. The filler material was ESAB 1. 2/12. 51 (AWS ER70S-6).

  • 17. Jonsson, Mikael
    et al.
    Karlsson, Lennart
    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.
    Thermal stresses and plate motion in butt-welding1983In: Numerical methods in thermal problems: proceedings of the third international conference, held in Seattle, USA, on 2nd - 5th August, 1983 / [ed] R.W. Lewis, Swansea: Pineridge Press , 1983, p. 270-279Conference paper (Refereed)
  • 18. Jonsson, Mikael
    et al.
    Karlsson, Lennart
    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.
    Thermal stresses, plate motion and hot-cracking in butt-welding1983In: Mechanical behaviour of materials - IV: proceedings of the fourth International conference, Stockholm, Sweden, 15-19 August 1983 / [ed] Janne Carlsson; Nils-Gunnar Ohlson, Oxford: Elsevier, 1983, p. 273-279Conference paper (Refereed)
  • 19. Jonsson, Mikael
    et al.
    Karlsson, Lennart
    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.
    Lindén, G.
    The influence of welding deformations on tolerance requirements in automatic butt welding1985Conference paper (Refereed)
  • 20. Jonsson, Mikael
    et al.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Sundin, Karl-Gustaf
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Experimental and numerical analysis of damped transient vibration of beam structures1989In: Proceedings of the International conference on noise and vibration: August 16-18, 1989 at Novetel Orchid Inn Singapore, Singapore: Nanyang Technological Institute , 1989, p. B.53-B.64Conference paper (Refereed)
  • 21. 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)
  • 22. 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.

  • 23. Josefson, B.L.
    et al.
    Jonsson, Mikael
    Karlsson, C.T.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Transformation plasticity effects on residual stresses in a butt welded pipe1990Conference paper (Refereed)
  • 24. Josefson, B.L.
    et al.
    Jonsson, Mikael
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, R.
    Karlsson, T.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Transient and residual stresses in a single-pass butt welded pipe1989In: Residual stresses: International conference : Papers / [ed] G. Beck; S. Denis; A. Simon, Elsevier, 1989, p. 497-503Conference paper (Refereed)
  • 25. Josefson, B.L.
    et al.
    Karlsson, Lennart
    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.
    Jonsson, Mikael
    Thermo-mechanical FE-analysis of butt-welding of a Cu-Fe canister for spent nuclear fuel1993In: Structural mechanics in reactor technology: transactions of the 12th International Conference on Structural Mechanics in Reactor Technology, Stuttgart, Germany, 15-20 August 1993, Amsterdam: Elsevier, 1993Conference paper (Refereed)
  • 26.
    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.

  • 27.
    Karlsson, Lennart
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindgren, Lars-ErikLuleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.Jonsson, Mikael
    Mechanical effects of welding: IUTAM Symposium, Luleå, Sweden, June 10-14, 19911992Collection (editor) (Other academic)
  • 28.
    Karlsson, Lennart
    et al.
    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.
    Jonsson, Mikael
    Josefson, L.
    Oddy, A.
    Modeling of residual stresses and distortion development1997In: Mathematical modelling of weld phenomena 3, London: Institute of Materials , 1997, p. 571-589Chapter in book (Other academic)
    Abstract [en]

    Four examples are used to illustrate the current ability to calculate residual stress and distortion in situations of varying complexity. The methodology used is capable of allowing for interactions between thermal, mechanical, and transformation processes. Experimental values for a 2.25Cr-1Mo ferritic stainless steel were used in the simulation. It seems possible to simulate most welding situations given sufficient computer resources

  • 29.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Carlestam, A.
    SSAB Oxelösund AB.
    Jonsson, Mikael
    Computational model of flame-cutting1993In: Journal of engineering materials and technology, ISSN 0094-4289, E-ISSN 1528-8889, Vol. 115, no 4, p. 440-445Article in journal (Refereed)
    Abstract [en]

    A computational model for simulation of flame-cutting has been developed. Two different cutting conditions are compared with respect to the residual stresses. The first case is a plate cut at room temperature and the other is the cutting of a preheated plate. The model depends on measured micro-structure to estimate the required heat input. The model is verified by comparing the calculations for the preheated plate with experimentally obtained residual stresses. Lower residual stresses in the preheated plate prevents subsequent cracking

  • 30.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsson, Mikael
    Accuracy and efficiency in computational plasticity1991In: Proceedings of the International Conference on Mechanics of Solids and Structures: Nanyang Technological University ; 11 - 13 September 1991 / [ed] Daniel T. Lwin; Frank W. Travis, Singapore: World Scientific and Engineering Academy and Society, 1991Conference paper (Refereed)
  • 31.
    Lindgren, Lars-Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsson, Mikael
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Linden, G.
    Deformations and stresses during automatic butt-welding1987In: The Effects of fabrication related stresses on product manufacture and performance: An International Conference / [ed] J.F. Alder, Cambridge: Welding Institute , 1987Conference paper (Refereed)
  • 32.
    Oldenburg, Mats
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Sandberg, L.
    Plannja HardTech AB.
    Bergman, Greger
    Plannja HardTech AB.
    Jonsson, Mikael
    Experiments with one-sided spray-cooling of steel plates for evaluation of thermo-mechanical material models1996In: Quenching and the control of distortion: proceedings of the 2nd International Conference on Quenching and the Control of Distortion, 4 - 7 November 1996, Cleveland Marriott Society Center, Cleveland, Ohio / [ed] George E. Totten, Materials Park, Ohio: ASM International, 1996, p. 267-273Conference paper (Refereed)
    Abstract [en]

    The quenching process of thin plates is studied. In many industrial applications of quenching, there is a need for simple tests for evaluation of analysis methods and material models for simulations. The presented study is part of a program for the simulation of the combined pressing and quenching process of thin-walled structures. This type of manufacturing process is used in, e.g., the production of side-impact protection beams for cars. By the use of an experiment with one-sided spray-cooling of a thin strip, large deformations can be studied and followed in time. The prediction of the deformation of the strip can be regarded as a one-dimensional problem where the curvature of the strip is sought. The thermo-mechanical behavior of the material can be evaluated throughout the time-history of the tests. In order to match the deformation of the plate, the material model must predict the temperature distribution through the thickness of the plate in each point in time, the phase transformations taking place in each layer of the thin plate and the stress and strain components in each layer. Experiments have been performed with a material (Inconel 600) without phase transformations in the actual temperature and time scale and with a material with only martensitic transformations. Analyses with a thermo-elastic-plastic material model with transformation plasticity included have been performed

  • 33.
    Sundin, Karl-Gustaf
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsson, Mikael
    A stiff and compact impact-force transducer based on strain measurement1985In: Experimental mechanics, ISSN 0014-4851, E-ISSN 1741-2765, Vol. 25, no 1, p. 48-53Article in journal (Refereed)
    Abstract [en]

    A stiff and compact transducer for both static and impact compressive forces has been developed. The principle of the transducer is based on measurement of tangential strain around the periphery of an axially loaded short and axisymmetric body. It is shown that for an appropriate choice of transducer geometry the output is nearly insensitive to the distribution of the force over the loaded surface. In an experimental investigation, a prototype of the transducer was subjected to both static and impact loads of different distributions. The results show only a few percent variation in transducer sensitivity for the load distributions used. The transducer consists essentially of a homogeneous body and is simple to make. The size and material can be chosen to fit special applications

  • 34.
    Sundin, Karl-Gustaf
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsson, Mikael
    Force transducer based on measurement of mean strain in a compact body1989In: Journal of Strain Analysis for Engineering Design, ISSN 0309-3247, E-ISSN 2041-3130, Vol. 24, no 1, p. 31-35Article in journal (Refereed)
    Abstract [en]

    A force transducer based on measurement of mean strain in a body has been developed. The transducer can be made stiff and compact and is therefore suitable for measurement of impact forces as well as static forces. An experimental test of a simple first prototype was performed using both static and impact loads with different distributions over the load-carrying area of the transducer. The results of the experiments show that the requirement of insensitivity to differences in load distribution is acceptably fulfilled. Improvements are expected to be possible if the transducer is made in a more accurate way.

  • 35.
    Tinnsten, Mats
    et al.
    Mittuniversitetet.
    Carlsson, Peter
    Mittuniversitetet.
    Jonsson, Mikael
    Stochastic optimization of acoustic response: a numerical and experimental comparison2002In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 23, no 6, p. 405-411Article in journal (Refereed)
    Abstract [en]

    The objective of the work presented is to compare results from numerical optimization with experimental data and to highlight and discuss the differences between two fundamentally different optimization methods. The problem domain is minimization of acoustic emission and the structure used in the work is a closed cylinder with forced vibration of one end. The optimization method used in this paper is simulated annealing (SA), a stochastic method. The results are compared with those from a gradient-based method used on the same structure in an earlier paper (see Tinnsten 2000).

  • 36. Troive, Lars
    et al.
    Jonsson, Mikael
    Numerical and experimental study of residual deformations due to double-J multi-pass butt-welding of a pipe-flange joint1994In: Proceedings of the First International IEMS Conference: Cocoa Beach, Florida, USA, March 14 - 16, 1994 / 1994 Annual International Conference on Industry, Engineering, and Management Systems / [ed] Yasser A. Hosni, 1994, p. 107-114Conference paper (Refereed)
  • 37. Troive, Lars
    et al.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsson, Mikael
    Axial collapse load of a girth butt-welded pipe1995In: Thermal stresses '95: proceedings of the First International Symposium on Thermal Stresses and Related Topics, June 5 - 7, 1995, Shizoka University, Shizuoka University , 1995, p. 565-568Conference paper (Refereed)
  • 38.
    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.

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