PSI - Issue 54

Jenny Köckritz et al. / Procedia Structural Integrity 54 (2024) 423–430 J. Köckritz / Structural Integrity Procedia 00 (2019) 000 – 000

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4. Conclusion In this paper, several weld fatigue assessment methods were applied and compared for the assessment of a multiaxially loaded EN AW 7020 aluminum cargo bicycle frame. Simplified specimens were utilized to compare the numerical results to experimental investigations for two multiaxial, in-phase and constant amplitude load cases. Additionally, investigations under a multiaxial, in-phase load collective were performed. The investigations show that for the complex tube structure of a bicycle frame, the standard assessment with the effective notch method (Hobbacher, 2016) has low applicability due to high modelling effort and computing time, while the standard method with hot spot stress (Niemi et al., 2018) leads to conservative results. In contrast, the seam weld fatigue method with an adjusted weld positioning is well applicable for complex tube structures. The results are reliable for multiaxial load cases with prevalent bending but shift to more conservative expected lifetimes with increasing amounts of torsion. Welds subjected to multiaxial loading with a high amount of torsion should be evaluated with the hot spot stress method for shear loading as recommended in Niemi et al. (2018). While evaluations for constant amplitude loads tend to be more conservative, the numerical evaluations performed with the load collective correspond better to the experimental results, even slightly overestimating the life span depending on the deployed material data. Acknowledgements The presented research was funded within the Project “SteigtUM” by the Federal Ministry of Education and Research (BMBF) with the funding reference number 16SV8267. References Altair User Handbook, 2021. Seam Weld Fatigue Analysis. Bolchoun, A., Wiebesiek, J., Kaufmann, H., Sonsino, C., 2014. 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Fatigue Life Prediction of MAG-Welded Thin-Sheet Structures. SAE Transactions 107, 1280-1286. Hobbacher, A.F., 2016. Recommendations for Fatigue Design of Welded Joints and Components, 2 nd Edition. In: International Institute of Welding (ed.) IIW Collection, Springer Köckritz, J., Fürstner, T., Kröger, M., 2022. Messung realer Kräfte und deren Auswirkung auf die numerische Lebensdauerberechnung – Ein Fallbeispiel aus der Entwicklung eines neuen Lastenfahrrades. Die neue Vielfalt – Herausforderungen an Fahrräder, Workshop des DVM Arbeitskreises Fahrradsicherheit. Berlin, Deutschland. Mensinger, M., 2018. Neubewertung und Ergänzung der Versuchsdaten zur DIN EN 1999-1-3 mit Fokus auf dem Kurzzeitfestigkeitsbereich, Schlussbericht zu IGF-Vorhaben Nr. 18629. Lehrstuhl für Metallbau, Technische Universität München. Mei, J., Dong, P., Xing, S., Vasu, A., Ganamet, A., Chung, J., Mehta, Y., 2021. 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