PSI - Issue 64

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

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 64 (2024) 1192–1199

SMAR 2024 – 7th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures Numerical and Experimental Study on Steel Members Retrofitted by Directed Energy Deposition Hamid Dahaghin a,b , Hessam Moshayedi b , Niels Pichler c,d , Lingzhen Li e , Maryam Mohri c , Chenglei Diao f , Masoud Motavalli a,c , Seyed Mehdi Zahrai a , Elyas Ghafoori b, *

a School of Civil Engineering, University of Tehran, 16th Azar Street, Tehran, Iran b Institute for Steel Construction, Leibniz University of Hannover, 30167 Hannover, Germany c Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland d ETH Zürich, Institute of Structural Engineering, 8093 Zürich, Switzerland e Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong f WAAM3D Limited, 5 Thornton Chase, Milton Keynes, MK14 6FD, United Kingdom f

Abstract Wire and arc additive manufacturing (WAAM) is a versatile technology with applications ranging from manufacturing to the strengthening and repair of aging components. This paper investigates the effectiveness of strengthening techniques using WAAM through both numerical simulations and experimental observations. A thermo-mechanical analysis is employed to predict the temperature and stress fields in repaired specimens. The results show that original cracks in the plate are arrested due to compressive residual stresses generated at the crack tip due to the WAAM process, as well as the increased stiffness around the cracked region. However, new cracks initiate at the edge of the plate/WAAM-material interface which corresponds to the high-stress state in the region. This issue is mitigated significantly by machining the WAAM sample into a pyramid shape, resulting in infinite life for the strengthened plate under fatigue loading. Fractography analysis aids in better understanding the mechanism of sample failure. In conclusion, the results underscore the potential of WAAM repair, offering a hopeful outlook for the future of steel structure maintenance by presenting it as a promising method for mitigating fatigue-induced damage in steel structures. © 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 SMAR 2024 Organizers Keywords : Metal 3D-printing; Fatigue repair; Fatigue life extension; Crack arrest; Thermo-mechanical analysis © 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 SMAR 2024 Organizers

* Corresponding author. Tel.: +49 511 762 2437 E-mail address: ghafoori@stahl.uni-hannover.de

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 SMAR 2024 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 SMAR 2024 Organizers 10.1016/j.prostr.2024.09.166