PSI - Issue 57

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2022) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

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ScienceDirect

Procedia Structural Integrity 57 (2024) 589–597

© 2024 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 Fatigue Design 2023 organizers Abstract The fatigue strength of structures made of rectangular (RHS) and circular hollow sections (CHS) is characterized by inhomogene ous stiffness distributions in the connection areas of braces and chord, which lead to high stress concentration factors (SCF). Using these SCFs in conjunction with structural SN-curves, the fatigue life can be estimated. In the preceding research project P1132, K joints made of CHS used a special weld design resulting in a local reinforcement of the gap area. The fatigue tests showed an increase in fatigue strength compared to conventional CHS K-joints. Based on this, in the research project FOSTA P1442, numer ical and experimental fatigue investigations were carried out on K-joints with shape-optimized gusset-plates. The use of gusset plates was intended to increase the fatigue strength of K-joints by relocating the position of the hot spot to areas with lower stresses or by reducing the stresses at the hot spot. For this purpose, three different gusset-plate geometries were investigated for five RHS- respectively three CHS-geometries. Variant 1 (shortened, slotted braces and gusset-plate attached to the chord), variant 2 (slotted braces also attached to the chord) and variant 3 (like V2, gusset-plate additionally passed through the underside of the chord). All components are circumferentially welded. The SCF of the three gusset-plate geometries are compared with the SCF of conventional K-joints. In addition, the SCF are compared with the required fabrication effort for the geometries under investigation. Finally, on this basis, a manufacturing recommendation for practical use is presented. © 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 Fatigue Design 2023 organizers Keywords: fatigue strength; gusset-plates; hollow sections; fatigue tests; shape optimization 1. Introduction The fatigue strength of structures made of rectangular (RHS) and circular hollow sections (CHS) is characterized by inhomogeneous stiffness distributions in the connection areas of braces and chord, which lead to high stress concentration factors (SCF). Using these SCFs in conjunction with structural SN-curves, the fatigue life can be estimated. Fatigue Design 2023 (FatDes 2023) Investigation of the Fatigue Strength of Shape Optimized Gusset Plates in Rectangular and Circular Hollow Section K-Joints Philipp Ladendorf a , Stefan Herion a , Matthias Winkler b , André Dürr b a CCTH Centre of Competence for Tubes and Hollow Sections, Schönfeldstraße 8, Karlsruhe 76135, Germany b Institute for Material and Building Research, University of Applied Sciences Munich, Karlstraße 6, Munich 80333, Germany

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 Fatigue Design 2023 organizers

2452-3216 © 2024 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 Fatigue Design 2023 organizers 10.1016/j.prostr.2024.03.065