PSI - Issue 31

M.L. Larsen et al. / Procedia Structural Integrity 31 (2021) 70–74 M.L Larsen, V. Arora, H.B. Clausen / Structural Integrity Procedia 00 (2019) 000–000

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stresses more perpendicular to a weld. However, in this paper only a single S-N curve is considered for the normal stresses and the shear stresses at the weld.

Fig. 4. Critical planes which are constant due to nominal stress state.

4. Conclusions In this paper, the results from an optimization of the weld orientation in a simple plate structure have been presented. Various fatigue criteria have been applied in the optimization algorithm to investigate the optimal designs considering the different approaches. The optimization has been performed by a newly developed optimization framework which focuses on easy implementation of different fatigue estimation methods. The results show that the traditional equivalent stress methods from the IIW and the EC3 optimizes such that the original weld is rotated 45 degrees to obtain the lowest fatigue damage. The results also show that the critical plane approaches used with the Findley and MWCM method, cannot optimize the structure due to the very simple stress state and as the nominal stress approach is used for extracting stresses. Acknowledgements This work has been supported by the Danish Energy Agency as part of the Energy Technology and Demonstration program (EUDP), grant number 64018-0508. References DS/EN, 2007. Eurocode 3: Design of steel structures - Part1-9: Fatigue. Danish Standards. Findley, W. N., 1959. A Theory for the Effect of Mean Stress on Fatigue of Metals Under Combined Torsion and Axial Load or Bending. Journal of Manufacturing Science and Engineering, 81, 301-305. Hobbacher, A. F., 2016. Recommendations for Fatigue Design of Welded Joints and Components. Springer International Publishing. HyperWorks., 2019. Altair HyperWorks Software. Maddox, S.J., 1991. Fatigue strength of welded structures, Abington Publ. MATLAB., 2020, Version 9.8.0.1396136 (R2020a) Update 3. Oest, J. Sørensen, R. Overgaard, L.C. Lund, E., 2017. Structural optimization with fatigue and ultimate life constraints of jacket structures for large offshore wind turbines, Structural and Multidisciplinary Optimization, Springer Nature, 55, 779-793. Pedersen, M., 2016, Multiaxial fatigue assessment of welded joints using the notch stress approach, International Journal of Fatigue, 83, 269-279. Suresh, S.; Lindström, S. B.; Thore, C.-J.; Torstenfelt, B. & Klarbring., 2019 A. Topology optimization using a continuous-time high-cycle fatigue model. Structural and Multidisciplinary Optimization, Springer Science and Business Media LLC. Susmel, L., 2009. Multiaxial notch fatigue, CRC Press Woodhead.