PSI - Issue 75

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia (2025) 000 – 000

ScienceDirect

www.elsevier.com/locate/procedia

Procedia Structural Integrity 75 (2025) 509–518

Fatigue Design 2025 (FatDes 2025) Identification of Local Elasto-Plastic Properties in Multi-Material Thin Aluminum Welded Structures through Experimental Methods, Modeling, and AI ℎ , 1 , ℎé , − ç , , , ℎ , a : Univ. Lille, CNRS, Centrale Lille, UMR 9013 - LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, F-59000 Lille, France b: Decathlon Technichal Office, B'TWIN Village - 4 rue du Professeur Langevin, 59000 Lille, France Abstract The growing development of soft mobility, especially electrically power assisted cycles ( EPAC), is leading to more complex frame geometry and greater loads. Therefore, the aim of this study, conducted in collaboration with Decathlon, is to enhance the understanding and simulation of the fatigue life of aluminium bike frames. The study specifically focuses on tube welding, a favoured crack initiation area. Scientifically, the challenges are centred on the emergence of a property gradient, multi-axial loading, and the thin tubular nature of the concerned areas. Firstly, to simplify the problem and overcome the difficulties associated to the geometry of bikes frame, micro-tensile tests instrumented by stereoscopic image correlation were carried out on flats shaped specimens to identify the constitutive laws in the different zones of interest close to the welded area. The instrumentation of these tests is based on stereoscopic image correlation, initially allowing access to in plan and out of plan displacement fields on the surface and subsequently, access to information related to the topology of the weld beads. The study of these kinematic fields has enabled the identification of areas of interest and the recalibration of material properties based on a representative numerical model. The identified material models show a 15% decrease in yield strength and a 31% increase in tangent modulus in the weld zone compared to the base metal, highlighting the necessity of zone-specific modelling.

1 * Corresponding author. Tel.: +33 6 77 70 04 18 E-mail address: arthur.thibault@decathlon.com

2452-3216 © 2025 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 2025 organizers

2452-3216 © 2025 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 the responsibility of Dr Fabien Lefebvre with at least 2 reviewers per paper 10.1016/j.prostr.2025.11.051