PSI - Issue 79

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 79 (2026) 224–232

© 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 IGF28 - MedFract3 organizers Keywords: Steel welded joints; Titanium welded joints; Hotspot stress; Strain Energy Density; finite element analysis Abstract The objective of this work is to validate, through finite element analysis, the use of the hotspot stress and Strain Energy Density (SED) approaches for the fatigue life assessment of welded T-joints made of structural steel and Ti-6Al-4V alloy. While these methods are well established for steel, their application to titanium is less straightforward due to the absence of material-specific FAT curves and SED scatter bands for welded configurations. To enable the application of the hotspot stress method to titanium joints, a preliminary approach based on the normalization of steel FAT curves with respect to the Young’s modulus was implemented. The SED method was instead applied by adopting the control radius and design curve derived for the base material. Both methodologies proved to be reliable for steel joints, whereas in the case of titanium, the results emphasized the limitations of these approaches and the need for further experimental data to establish suitable design references. 1. Introduction Welded joints are widely used in structural and mechanical applications due to their cost-effectiveness and versatility. Because of the inherent stress concentrations (NDIAYE et al., (2007)) and metallurgical alterations (Wang et al., (2024)) induced by welding, fatigue represents the most critical failure mode for such joints. Several 28th International Conference on Fracture and Structural Integrity - 3rd Mediterranean Conference on Fracture and Structural Integrity Strain Energy Density and hot-spot stress analysis of welded T joints for marine applications Santi Marchetta a *, Pasqualino Corigliano a , Giulia Palomba a , Giacomo Risitano a , Dario Francesco Santonocito a a Dipartimento di Ingegneria, University of Messina, Contrada di Dio 98158, Messina (ME), Italy

* Corresponding author. Tel.: +393456668366 E-mail address: santi.marchetta@studenti.unime.it

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 IGF28 - MedFract3 organizers 10.1016/j.prostr.2025.12.328