| 1. |
- Benckert, Lars, et al.
(författare)
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Measuring 3-D displacement of a surface using the white light speckle technique
- 1986
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 599, s. 207-210
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Tidskriftsartikel (refereegranskat)abstract
- 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
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| 2. |
- Benckert, Lars, et al.
(författare)
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Measuring true in-plane displacements of a surface by stereoscopic white-light speckle photography
- 1987
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Ingår i: Optical Engineering. - : SPIE-Intl Soc Optical Eng. - 0091-3286 .- 1560-2303. ; 26:2, s. 167-169
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Tidskriftsartikel (refereegranskat)abstract
- 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
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| 3. |
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| 4. |
- Jonsson, Mikael, et al.
(författare)
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Deformations and stresses in butt-welding of large plates with special reference to the mechanical material properties
- 1985
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Ingår i: Journal of engineering materials and technology. - : ASME International. - 0094-4289 .- 1528-8889. ; 107:4, s. 265-270
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
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| 6. |
- Jonsson, Mikael
(författare)
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Experimental and numerical study of deformations and stresses in butt-welded plates
- 1986
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 7. |
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| 8. |
- Jonsson, Mikael, et al.
(författare)
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Experimentally determined transient and residual-stresses in a butt-welded pipe
- 1988
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Ingår i: Journal of Strain Analysis for Engineering Design. - 0309-3247 .- 2041-3130. ; 23:1, s. 25-31
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Tidskriftsartikel (refereegranskat)abstract
- 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
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| 9. |
- Jonsson, Mikael, et al.
(författare)
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Kan svetsegenspänningar och svetsdeformationer förutsägas?
- 1986
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Ingår i: Svetsen. - 0039-7091. ; 45:5, s. 6-9
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 10. |
- Jonsson, Mikael, et al.
(författare)
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Measurements of residual deformations in butt-welded plates by use of the white light speckle technique
- 1986
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Ingår i: Journal of Strain Analysis for Engineering Design. - 0309-3247 .- 2041-3130. ; 21:4, s. 243-246
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Tidskriftsartikel (refereegranskat)abstract
- 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
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