| 1. |
- Andersson, Björn, 1989, et al.
(författare)
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Computationally efficient simulation methodology for railway repair welding: cyclic plasticity, phase transformations and multi-phase homogenization
- 2024
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Ingår i: Journal of Thermal Stresses. - 0149-5739 .- 1521-074X. ; 47:2, s. 164-188
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Tidskriftsartikel (refereegranskat)abstract
- The in-situ railway repair welding process consists of multiple weld passes, which makes it significantly different from other rail welding processes. In this study, finite element simulations of repair welding are performed to predict the resulting microstructure and residual stresses. To accurately simulate the material behaviour, the modelling includes phase transformation kinetics, cyclic hardening plasticity, transformation induced plasticity, and multi-phase homogenization. More specifically, four different homogenization methods are investigated: isostrain, isostress, self-consistent and linear mixture rule. The performance of the material modelling is demonstrated by simulating multiple weld passes using a classical three-bar welding experiment. Based on the results, the self-consistent method and linear mixture rule are used in a 3D full-scale railhead repair weld simulation, in which the former generates a more realistic mechanical response. The immense computational cost associated with 3D full-scale, full-detail multi-pass welding simulations is addressed by exploring different model reduction schemes. From this study, a 2D generalized plane strain model, extended with out-of-plane axial and bending stiffness, is found to replicate the full-scale model at a mere fraction of the computational cost. Finally, the longitudinal residual stress distribution obtained from the reduced model is shown to correlate well with experimental measurements.
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| 2. |
- Andersson, Björn, 1989, et al.
(författare)
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Homogenization based macroscopic model of phase transformations and cyclic plasticity in pearlitic steel
- 2022
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Ingår i: Journal of Thermal Stresses. - : Informa UK Limited. - 0149-5739 .- 1521-074X. ; 45:6, s. 470-492
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Tidskriftsartikel (refereegranskat)abstract
- In this contribution macroscopic modeling of phase transformations and mechanical behavior of low alloy steels are developed and investigated. Such modeling is of importance in simulations of transient thermo-mechanical processes which can cause phase transformations, examples from the railway industry include train braking induced frictional heating as well as rail grinding and welding operations. We adopt a modeling approach which includes phase transformation kinetics and individual constitutive models for the phases in combination with different homogenization methods. Algorithmic implementations of the isostrain, isostress and self-consistent homogenization methods are presented and demonstrated in finite element simulations of a laser heating experiment. Stress field results from the different homogenization methods are compared against each other and also against experimental data. The importance of including transformation induced plasticity in the modeling is highlighted, as well as the multi-phase stages of the heating and cooling.
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| 3. |
- Andersson, Börje, et al.
(författare)
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Thermal stresses in large butt-welded plates
- 1981
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Ingår i: Journal of thermal stresses. - : Informa UK Limited. - 0149-5739 .- 1521-074X. ; 4:3-4, s. 491-500
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Tidskriftsartikel (refereegranskat)abstract
- In shipyard panel-production lines several rectangular plates ae butt welded to form large panels. One problem is the tendency of hot cracking in the end portion of the butt weld. In this paper transient temperature fields and stress fields in butt-welded plates are calculated using the finite-element method. The calculations are performed for different welding speeds, for different heat inputs, and for one-sided and two-sided welding.
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| 4. |
- Bargmann, Swantje, 1980, et al.
(författare)
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Material Forces in Non-Classical Thermo-Hyperelasticity
- 2009
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Ingår i: Journal of Thermal Stresses. - : Informa UK Limited. - 0149-5739 .- 1521-074X. ; 32:4, s. 361-393
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Tidskriftsartikel (refereegranskat)abstract
- The contribution's main objective is the treatment of non-classical nonlinear thermoelasticity based on the approach of Green and Naghdi within the context of the material force method. Material forces have proven to be well suited for the examination of defect mechanics and have become a very powerful and active research topic over the last decades. The numerical realization is based on finite elements in space as well as in time. Examples of investigating material forces within Green-Naghdi thermoelasticity are provided.
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| 5. |
- Bergman, Greger, et al.
(författare)
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Verification of thermomechanical material models by thin-plate quenching simulations
- 1997
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Ingår i: Journal of thermal stresses. - : Informa UK Limited. - 0149-5739 .- 1521-074X. ; 20:7, s. 679-695
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Tidskriftsartikel (refereegranskat)abstract
- A computational model for quenching simulations of thin plates has been developed. The model is examined by comparisons with experiments with one-sided water spray cooling. With this experiment, the thermomechanical behavior of the material can be monitored throughout the time history of the test. Experiments have been performed with a material that undergoes only martensitic transformation during quenching. For the conditions examined the plate exhibits permanent deformation after quenching. In the stress calculation, transformation plasticity is included in the effective-stress-function (ESF) algorithm as an additional strain component related to the stress and to the progress of transformation. Analyses of the present experiments show that the permanent deformation of the plate is exclusively due to transformation plasticity
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| 6. |
- Lindgren, Lars-Erik
(författare)
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Finite element modeling and simulation of welding. Part 1 : Increased complexity
- 2001
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Ingår i: Journal of thermal stresses. - : Informa UK Limited. - 0149-5739 .- 1521-074X. ; 24:2, s. 141-192
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Tidskriftsartikel (refereegranskat)abstract
- Simulation of welding has advanced from the analysis of laboratory setups to real engineering applications during the last three decades. This development is outlined and the directions for future research are summarized in this review, which consists of three parts. This part shows that the increased complexity of the models gives a better description of the engineering applications. The important development of material modeling and computational efficiency are outlined in Parts 2 and 3, respectively.
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| 7. |
- Lindgren, Lars-Erik
(författare)
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Finite element modeling and simulation of welding. Part 2 : Improved material modeling
- 2001
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Ingår i: Journal of thermal stresses. - : Informa UK Limited. - 0149-5739 .- 1521-074X. ; 24:3, s. 195-231
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Tidskriftsartikel (refereegranskat)abstract
- Simulation of welding has advanced from the analysis of laboratory setups to real engineering applications during the last three decades. This development is outlined and the directions for future research are summarized in this review, which consists of three parts. The material modeling is maybe the most crucial and difficult aspect of modeling welding processes. The material behavior may be very complex for the large temperature range considered.
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| 8. |
- Lindgren, Lars-Erik
(författare)
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Finite element modeling and simulation of welding. Part 3 : Efficiency and integration
- 2001
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Ingår i: Journal of thermal stresses. - : Informa UK Limited. - 0149-5739 .- 1521-074X. ; 24:4, s. 305-334
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Tidskriftsartikel (refereegranskat)abstract
- Welding simulation has advanced from the analysis of laboratory setups to real engineering applications during the last three decades. This development is outlined and the directions for future research are summarized in this review, which consists of three parts. This parts focuses on computational strategies and how they are integrated with other methods to facilitate the use of simulations in engineering. These developments have lead to the increased application of welding simulations in industry.
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| 9. |
- Lindgren, Lars-Erik, et al.
(författare)
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Modeling of thermal stresses in low alloy steels
- 2019
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Ingår i: Journal of thermal stresses. - : Taylor & Francis. - 0149-5739 .- 1521-074X. ; 42:6, s. 725-743
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Tidskriftsartikel (refereegranskat)abstract
- Computing the evolution of thermal stresses accurately requires appropriate constitutive relations. This includes both the thermal and mechanical aspects, as temperature is the driver to thermal stresses. The paradigm of Integrated Computational Materials Engineering (ICME) aims at being able to quantitatively relate process-structure-property of a material. The article describes physics based models, denoted bridging elements, which are one step towards the vision of ICME. They couple material structure with heat capacity, heat conductivity, thermal and transformation strains and elastic properties for hypo-eutectoid steels. The models can account for the chemical composition of the steel and its processing, i.e. thermomechanical history, giving the evolution of the microstructure and the corresponding properties.
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| 10. |
- Lindgren, Lars-Erik, et al.
(författare)
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Thermal stresses and computational welding mechanics
- 2019
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Ingår i: Journal of thermal stresses. - : Taylor & Francis. - 0149-5739 .- 1521-074X. ; 42:1, s. 107-121
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Tidskriftsartikel (refereegranskat)abstract
- Computational welding mechanics (CWM) have a strong connection to thermal stresses, as they are one of the main issues causing problems in welding. The other issue is the related welding deformations together with existing microstructure. The paper summarizes the important models related to prediction of thermal stresses and the evolution of CWM models in order to manage the large amount of ‘welds’ in additive manufacturing.
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