PSI - Issue 75

Carl-Fredrik Lind et al. / Procedia Structural Integrity 75 (2025) 519–529 Carl-Fredrik Lind et al./ Structural Integrity Procedia (2025)

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7. Discussions The results demonstrate strong agreement between the automated Master S-N curve method and the effective notch approach, despite the former operating on significantly coarser shell meshes. This supports the methods validity for preliminary fatigue screening, where speed and scalability are critical. In most cases, the automated method predicted slightly shorter fatigue life than the effective notch method. This conservative bias is desirable in design assessments, as it helps ensure that potentially critical welds are not overlooked. Deviations observed, particularly in angled joints, are likely due to local geometric effects not fully captured by the coarse mesh or the simplified structural stress approximation. However, the method has limitations. It currently supports only welds modeled with shell elements and assumes relatively consistent plate geometries. Welds involving complex three-dimensional features, non-uniform thickness transitions, or solid element meshes fall outside its current scope. These cases would require either mesh refinement or alternative evaluation methods. 8. Conclusions  The Master S-N curve method was successfully automated for fatigue evaluation of welds in FEM models, enabling fast and conservative screening.  Validation against the effective notch method showed strong agreement, supporting the reliability of the approach on coarse shell meshes.  DBSCAN clustering allowed for fully automated weld line identification without manual intervention.  The method is best suited for shell-element models and standard weld geometries, with future extension needed for more complex cases. 9. Future Work  Extend the method to support solid and mixed-element meshes.  Improve accuracy for complex geometries and non-standard weld types.  Integrate automatic mesh quality checks to enhance robustness. Acknowledgement This research was financially supported by Scania CV AB and KTH Royal Institute of Technology. The support is gratefully acknowledged. References Baumgartner, J., Hobbacher, A. F., & Rennert, R. (2020). Fatigue assessment of welded thin sheets with the notch stress approach – Proposal for recommendations. International Journal of Fatigue , 140 , 105844. https://doi.org/10.1016/J.IJFATIGUE.2020.105844 Dong, P. (2001). A structural stress definition and numerical implementation for fatigue analysis of welded joints. International Journal of Fatigue , 23 (10), 865–876. https://doi.org/10.1016/S0142 1123(01)00055-X Dong, P., & Hong, J. K. (2004). The master S-N curve approach to fatigue of piping and vessel welds. Welding in the World , 48 (1–2), 28–36. https://doi.org/10.1007/BF03266411/METRICS Dong, P., Hong, J. K., Osage, D., & Prager, M. (2003). Assessment of ASME’s FSRF rules for vessel and piping welds using a new structural stress method. Welding in the World , 47 (1–2), 31–43. https://doi.org/10.1007/BF03266376/METRICS Dong, P., Prager, M., & Osage, D. (2007). The design master S-N curve in asme div 2 rewrite and its validations. Welding in the World , 51 (5–6), 53–63. https://doi.org/10.1007/BF03266573/METRICS Ester, M., Kriegel, H., Sander, J., & Xu, X. (1996). A Density-Based Algorithm for Discovering Clusters in Large Spatial Databases with Noise. Knowledge Discovery and Data Mining .