PSI - Issue 54

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Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2023) 000 – 000 Structural Integrity Procedia 00 (2023) 000 – 000 Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ

www.elsevier.com/locate/procedia

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Procedia Structural Integrity 54 (2024) 423–430 International Conference on Structural Integrity 2023 (ICSI 2023) Fatigue behavior and numerical assessment of welded aluminum EN AW 7020 tube joints under multiaxial loading Jenny Köckritz a, *, Thomas Fürstner a , Robert Szlosarek a , Matthias Kröger a a Technische Universität Bergakademie Freiberg, Institute for Machine Elements, Design and Manufacturing. Agricolastraße 1, 09599 Freiberg Abstract Cargo bicycle frames have to fulfill highest lightweight requirements and are subjected to demanding loading conditions, which lead to multiaxial stresses in critical weld regions. Reliable fatigue assessment is crucial for a fast development and production process, especially for small batch sizes. In this study, several numerical weld assessment methods are compared with experimental results in the case of multiaxially loaded EN AW 7020 (AlZn4,5Mg1) tungsten inert gas (TIG) welded tube connections with no subsequent heat treatment. Their applicability on the use case of a cargo bicycle frame manufactured with the same material and weld method is discussed. For the numerical and experimental investigations, simplified tube-plate joint specimen with fillet welds are utilized. Fatigue tests are performed with fully reversed, in phase bending and torsion, causing multiaxial loading of the weld. This loading is subjected to the specimen with a constant amplitude as well as a load collective. The load collective was obtained from representative driving situations with the cargo bicycle. The welds are assessed with several numerical assessment methods, including effective notch method, hot spot stress method and a solver-specific hot spot stress-based assessment method. For the solver-specific weld fatigue assessment method several modelling parameters proved to be critical for a reliable result, such as the material parameters themselves and the bending ratio. Element size and accurately placed weld connectors showed to have less significant influence. For the constant amplitude loading the numerical and experimental results display some divergence, with all assessment methods showing exceedingly conservative lifetimes. In contrast, for the load collective, the hot spot stress-based solver-specific assessment method leads to satisfactory compliance with the experimental results. © 2023 The Authors, Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers International Conference on Structural Integrity 2023 (ICSI 2023) Fatigue behavior and numerical assessment of welded aluminum EN AW 7020 tube joints under multiaxial loading Jenny Köckritz a, *, Thomas Fürstner a , Robert Szlosarek a , Matthias Kröger a a Technische Universität Bergakademie Freiberg, Institute for Machine Elements, Design and Manufacturing. Agricolastraße 1, 09599 Freiberg Abstract Cargo bicycle frames have to fulfill highest lightweight requirements and are subjected to demanding loading conditions, which lead to multiaxial stresses in critical weld regions. Reliable fatigue assessment is crucial for a fast development and production process, especially for small batch sizes. In this study, several numerical weld assessment methods are compared with experimental results in the case of multiaxially loaded EN AW 7020 (AlZn4,5Mg1) tungsten inert gas (TIG) welded tube connections with no subsequent heat treatment. Their applicability on the use case of a cargo bicycle frame manufactured with the same material and weld method is discussed. For the numerical and experimental investigations, simplified tube-plate joint specimen with fillet welds are utilized. Fatigue tests are performed with fully reversed, in phase bending and torsion, causing multiaxial loading of the weld. This loading is subjected to the specimen with a constant amplitude as well as a load collective. The load collective was obtained from representative driving situations with the cargo bicycle. The welds are assessed with several numerical assessment methods, including effective notch method, hot spot stress method and a solver-specific hot spot stress-based assessment method. For the solver-specific weld fatigue assessment method several modelling parameters proved to be critical for a reliable result, such as the material parameters themselves and the bending ratio. Element size and accurately placed weld connectors showed to have less significant influence. For the constant amplitude loading the numerical and experimental results display some divergence, with all assessment methods showing exceedingly conservative lifetimes. In contrast, for the load collective, the hot spot stress-based solver-specific assessment method leads to satisfactory compliance with the experimental results. © 2023 The Authors, Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0 ) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers

* Jenny Köckritz. Tel.: +49 3731393855; E-mail address: jenny.koeckritz@imkf.tu-freiberg.de

2452-3216 © 2023 The Authors, Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers 2452-3216 © 2023 The Authors, Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers * Jenny Köckritz. Tel.: +49 3731393855; E-mail address: jenny.koeckritz@imkf.tu-freiberg.de

2452-3216 © 2023 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the ICSI 2023 organizers 10.1016/j.prostr.2024.01.102