| 1. |
- Barsoum, Zuheir, et al.
(författare)
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Fatigue strength evaluation of friction stir welded aluminium joints using the nominal and notch stress concepts
- 2012
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Ingår i: Materials & Design. - : Elsevier BV. - 0261-3069. ; 41, s. 231-238
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Tidskriftsartikel (refereegranskat)abstract
- In this study the fatigue strength is investigated for Friction Stir Welded (FSW) overlap and butt welded joints in different thicknesses based on nominal and effective notch stress concepts. The fatigue test results are compared with fatigue strength recommendations according to EN 1999-1-3 and International Institute of Welding (IIW). The results are also compared with available published data and Finite Element Analysis (FEA) is carried out to investigate the effect of plate thickness and nugget size on the fatigue strength of overlap joints. 3-3 mm butt welded joints shows the highest fatigue strength in comparison with 3-5 mm butt welded and overlap joints. Slopes of the SN-curves for two different joint types differ from the slope recommended by IIW. A specific failure trend is observed in overlap FSW joints. However, the slopes of the SN-curves are in close agreement with slopes found in EN 1999-1-3. The slopes of various published results and test results presented in this study are in good agreement with each other. The suggested fatigue design curves for the nominal and effective notch stress concept have a higher slope than given for fusion welds by IIW.
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| 2. |
- Barsoum, Zuheir, 1978-, et al.
(författare)
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Ultimate Strength Capacity of Welded Joints in High Strength Steels
- 2017
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Ingår i: 2nd International Conference on Structural Integrity, ICSI 2017. - : Elsevier. ; , s. 1401-1408
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Konferensbidrag (refereegranskat)abstract
- High strength steels are nowadays used in a wide range of weight lifting applications, e.g. spreaders and cranes, where there is a demand on lightweight design of these structures with increased structural performance where the welds become more sensitive to failure. This study focuses on investigating the influence of the mismatch in the yield strength of the weld filler material and the welds penetration depth on the ultimate strength capacity and failure modes of butt and fillet welded high strength steels of yield strength in the range of 350 960 MPa. The load carrying capacities of these mentioned joints are evaluated with experiments and compared with the estimations by finite element analysis (FEA), and design rules in Eurocode 3 and American Welding Society Code AWS D1.1. Fully penetrated joint with under-matched filler material is more ductile and the ultimate strength capacity of base plate can be achieved. It is observed that joints with under-matched filler material are more sensitive to penetration ratio. This influence is more pronounced in joints in S960 steel welded with under-matched filler material. It is also found that the design rules in Eurocode3 (valid for design of welded joints in steels of grade up to S700) can be extended to designing of welds in S960 steels using correlation factor of one.
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| 3. |
- Bhatti, Ayjwat Awais, et al.
(författare)
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Development of a finite element simulation framework for the prediction of residual stresses in large welded structures
- 2014
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Ingår i: Computers & structures. - : Elsevier BV. - 0045-7949 .- 1879-2243. ; 133, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- In this study a framework for efficient prediction of residual stresses in large welded structure is proposed. For this purpose different finite element simulation approaches available in literature are implemented on a large bogie beam structure. Among all approaches rapid dumping approach used minimum computational time and also it showed qualitatively good agreement with X-ray diffraction measurements for welding residual stresses. Moreover, gradual weld bead deposition approach predicted more accurate results when compared with the experimental measurements and other approaches. Also, by using substructuring approach the computational time is significantly reduced with an acceptable accuracy of predicted welding residual stresses.
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| 4. |
- Delkhosh, Ehsan, et al.
(författare)
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Fracture mechanics and fatigue life assessment of box-shaped welded structures : FEM analysis and parametric design
- 2020
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Ingår i: Welding in the World. - : Springer. - 0043-2288 .- 1878-6669. ; 64:9, s. 1535-1551
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Tidskriftsartikel (refereegranskat)abstract
- In this study, Linear Elastic Fracture Mechanics (LEFM) approach is used to evaluate the fatigue strength of a box-shaped welded structure. A parametric study is also undertaken to study the effect of various weld parameters on the fatigue strength, such as lack of weld metal penetration, load position, and plate thicknesses. FRANC3D software was adopted to obtain the stress intensity factor values for two types of full-length and intermediate crack sizes, located at the critical region of the weld of the box-shaped structure. It was concluded that the LEFM approach could capture the crack propagation from the weld root reasonably well under the given conditions and estimate residual fatigue life of the welded structures conservatively. Compared to fatigue life estimations by nominal stress method (1,714,564 cycles) or effective notch stress method (63,385 cycles), the LEFM approach can estimate the residual life more accurately. Especially for intermediate (4 mm) lack of penetration (LOP) of weld metal case (589,198 cycles) in comparison to the experiments (1,216,595 cycles). The parametric study showed that the fatigue life increases with increase in the thickness of flanges, lesser LOP in the weld root, and when load is applied more toward the center of the plate.
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| 5. |
- Hultgren, Gustav, et al.
(författare)
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Mapping of scatter in fatigue life assessment of welded structures—a round-robin study
- 2021
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Ingår i: Welding in the World. - : Springer Science and Business Media Deutschland GmbH. - 0043-2288 .- 1878-6669. ; 65:9, s. 1841-1855
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Tidskriftsartikel (refereegranskat)abstract
- A round-robin study has been carried out within a national project in Sweden with the addition of an international participant, where several industrial partners and universities are participating. The project aims to identify variation and sources of variation in welding production, map scatter in fatigue life estimation, and define and develop concepts to reduce these, in all steps of product development. The participating organisations were asked to carry out fatigue life assessment of welded box structures, which is a component in load-carrying structures. The estimations of fatigue life have also been compared with fatigue test results. Detailed drawings, loads and material data were also given to the participants. The participants were supposed to use assessment methods based on global and local stresses using the design codes or recommendations they currently use in-house. Differences were identified between both methods and participants using the same codes/recommendations. Applicability and conditions from the cases in the codes were also identified to be differently evaluated between the participants. It could be concluded that for the applied cases the nominal stress method often overestimated the fatigue life and had a high scatter in the estimations by different participants. The effective notch method is conservative in comparison to the life of tested components with little scatter between the results derived by the participants.
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| 6. |
- Håkansson, Joel, et al.
(författare)
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Fatigue strength assessment of cover plate joints subjected to axial and bending loading
- 2023
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Ingår i: Fatigue & Fracture of Engineering Materials & Structures. - : Wiley. - 8756-758X .- 1460-2695. ; 46:5, s. 1947-1968
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates stress-based fatigue assessment methods to determine their applicability to welded cover plate joints subject to axial and bending loading. The nominal stress (NS), hot spot stress (HSS), 1 mm stress (OM), effective notch stress (ENS), theory of critical distances (TCD), and stress averaging (SA) methods are covered, and their accuracy and reliability are evaluated. To the best of the authors' knowledge, there is limited fatigue test data available for cover plate joints subjected to bending loading. In this study, fatigue tests are performed with cover plate joints under axial and bending loading. Evaluation of the fatigue assessment methods is based on the test results. It is observed that for axial loading, the ENS and OM method have the highest accuracy. For bending, the OM method is non-conservative, and the other methods are overly conservative. Using design curves recommended for thin-walled welded joints subjected to bending highly improves accuracy.
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| 7. |
- Karlsson Hagnell, Mathilda, et al.
(författare)
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Design implications and opportunities of considering fatigue strength, manufacturing variations and predictive lcc in welds
- 2021
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Fatigue strength dictates life and cost of welded structures and is often a direct result of initial manufacturing variations and defects. This paper addresses this coupling through proposing and applying the methodology of predictive life-cycle costing (PLCC) to evaluate a welded structure exhibiting manufacturing-induced variations in penetration depth. It is found that if a full-width crack is a fact, a 50% thicker design can result in life-cycle cost reductions of 60% due to reduced repair costs. The paper demonstrates the importance of incorporating manufacturing variations in an early design stage to ensure an overall minimized life-cycle cost. © 2021 by the authors.
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| 8. |
- Khurshid, Mansoor, et al.
(författare)
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Behavior of compressive residual stresses in high strength steel welds induced by high frequency mechanical impact treatment
- 2014
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Ingår i: Proceedings of the ASME Pressure Vessels and Piping Conference 2013. - : ASME Press. - 9780791855690
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Konferensbidrag (refereegranskat)abstract
- Residual stress state plays an important role in the fatigue life of welded structures. They can be beneficial or detrimental, depending on the nature of residual stresses. High frequency mechanical impact (HFMI) treatment is a post-weld fatigue improvement technique for welded joints. In this research work the behavior of compressive residual stresses induced in welded joints in high strength steels (HSS) by HFMI treatment has been investigated. Longitudinal non load carrying attachments in HSS are tested with constant amplitude (CA) and variable amplitude (VA) loading. Stress concentration factors have been calculated using Finite Element Analysis (FEA). Residual stresses have been measured at different cycles during fatigue testing using X-ray diffractiontechnique. It is observed that the induced residual stresses are quite stable with some relaxation in CA and VA loading. The overloads in VA loading seem to be more detrimental. Relaxation of residual stresses is more obvious in VA tests.
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| 9. |
- Khurshid, Mansoor, et al.
(författare)
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Behavior of compressive residual stresses in high strength steel welds induced by high frequency mechanical impact treatment
- 2014
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Ingår i: Journal of Pressure Vessel Technology-Transactions of the ASME. - : ASME International. - 0094-9930 .- 1528-8978. ; 136:4, s. 041404-
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Tidskriftsartikel (refereegranskat)abstract
- Residual stress state plays an important role in the fatigue life of welded structures. The effect can be beneficial or detrimental, depending on the nature of residual stresses. High frequency mechanical impact (HFMI) treatment is a postweld fatigue improvement technique for welded joints. In this research work the behavior of compressive residual stresses induced in welded joints in high strength steels (HSS) by HFMI treatment has been investigated. Longitudinal nonload carrying attachments in HSS are tested with constant amplitude (CA) and variable amplitude (VA) fatigue loading. Stress concentration factors have been calculated using finite element analysis (FEA). Residual stresses have been measured at different cycles during fatigue testing using X-ray diffraction technique. It is observed that the induced residual stresses are quite stable with some relaxation in CA and VA loading. The overloads in VA loading seem to be more detrimental. Relaxation of residual stresses is more obvious in VA tests.
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| 10. |
- Khurshid, Mansoor, et al.
(författare)
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Load Carrying Capacities of Butt Welded Joints in High Strength Steels
- 2015
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Ingår i: Journal of engineering materials and technology. - : ASME International. - 0094-4289 .- 1528-8889. ; 137:4
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to investigate the influence of yield strength of the filler material and weld metal penetration on the load carrying capacity of butt welded joints in high-strength steels (HSS) (i.e., grade S700 and S960). These joints are manufactured with three different filler materials (under-matching, matching, and over-matching) and full and partial weld metal penetrations. The load carrying capacities of these mentioned joints are evaluated with experiments and compared with the estimations by finite element analysis (FEA), and design rules in Eurocode3 and American Welding Society Code AWS D1.1. The results show that load carrying estimations by FEA, Eurocode3, and AWS D1.1 are in good agreement with the experiments. It is observed that the global load carrying capacity and ductility of the joints are affected by weld metal penetration and yield strengths of the base and filler materials. This influence is more pronounced in joints in S960 steel welded with under-matched filler material. Furthermore, the base plate material strength can be utilized in under-matched butt welded joints provided appropriate weld metal penetration and width is assured. Moreover, it is also found that the design rules in Eurocode3 (valid for design of welded joints in steels of grade up to S700) can be extended to designing of welds in S960 steels by the use of correlation factor of one.
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