| 1. |
- Jansson, E, et al.
(författare)
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On the acoustical function of the violin
- 1997
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Ingår i: 25. Congresso nazionale : Perugia, 21-23 maggio 1997 : atti / Associazione italiana di acustica.
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Konferensbidrag (refereegranskat)
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| 2. |
- Lindgren, Lars-Erik, et al.
(författare)
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Simulation of multipass welding of a thick plate
- 1999
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Ingår i: International Journal for Numerical Methods in Engineering. - 0029-5981 .- 1097-0207. ; 44:9, s. 1301-1316
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
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| 4. |
- Runnemalm, Henrik, et al.
(författare)
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Accuracy in thermal analysis of laser
- 1995
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Ingår i: Computational methods and experimental measurements VII. - Southampton : WIT Press. - 1853123137 ; , s. 85-92
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Konferensbidrag (refereegranskat)abstract
- 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
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| 5. |
- Runnemalm, Henrik
(författare)
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Efficient finite element modelling and simulation of welding
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents development of methods, methodologies and tools for efficient finite element modelling and simulation of welding. A novel 8- to 16-noded solid shell element has been developed. It uses only displacement degrees of freedom, thus it can easily be connected with a regular brick element. The element has proven to perform well in standard tests for shell as well as in geometrical and material non-linear problems. An error based adaptive remeshing scheme has been developed. It is found that the combination of the two error measures, based on the heat flux and the effective stress, is predicting an accurate mesh for a plate and a pipe welding case. To improve the efficiency of material addition in multipass welding two different strategies was compared. These two strategies, named quiet and inactive element, were used in a simulation of a very thick plate. Results showed that the inactive element strategy was preferable in terms of numerical efficiency. A generic process methodology is used to identify and develop critical activities in the modelling and simulation of welding. The methodology is used to compare simulation results of elementary case studies to results of more refined analysis. The elementary case studies is suggested to support decision making in the early design phase of product development.
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| 6. |
- Runnemalm, Henrik, et al.
(författare)
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Finite element simulation of residual deformation induced by laser welding
- 1997
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Ingår i: Proceedings. - Croydon : Automotive automation. - 947719644 ; , s. 329-335
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Konferensbidrag (refereegranskat)abstract
- This paper deals with the residual deformations introduced in a thin walled pipe by laser welding. Both numerical simulations and experimental measurements have been performed. Laser welding has been adopted for an increasing number of applications. Some preferable characteristics of laser welding are high welding speed and low heat input. Laser welding of thin walled structures gives smaller residual distortions than other welding processes. One of the main objectives in this paper is to verify the theoretical finite element model by experiments. The calculated temperatures show good agreement with measured values. The calculated deformations agree fairly well with measured values except for values at the center line of the weld. Example material was steel 304.
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| 7. |
- Runnemalm, Henrik, et al.
(författare)
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Investigation of residual stresses in a laser welded pipe by finite element simulations and neutron diffraction measurements
- 1997
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Ingår i: The Fifth International Conference on Residual Stresses - ICRS-5. - Linköping : Linköping University Electronic Press. - 9172192100 ; , s. 183-188
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Konferensbidrag (refereegranskat)abstract
- Finite element analysis and neutron diffraction were used to evaluate the radial, axial and hoop residual strains in a thin walled pipe with autogenous laser butt girth weld. The pipe, 50 mm inside radius and 2 mm in thickness, was made of AISI 304 stainless steel. Laser welding was carried out using a 2700 W laser, with helium as shielding gas. The results from the numerical and experimental methods were compared.
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| 8. |
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