PSI - Issue 37

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

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Procedia Structural Integrity 37 (2022) 873–879

© 2022 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 Pedro Miguel Guimaraes Pires Moreira Abstract This study aims to monitor the fatigue crack tip through a contactless optical method. A Middle Tension (MT) specimen is initially prepared by submitted it to a cyclic fatigue loading, in order to generate a crack with a specified length. Then, the cracked specimen is statically loaded under a uniaxial tensile condition, and Electronic Speckle Pattern Interferometry (ESPI) is employed to monitor the crack tip. During specimen loading with incremental force values, the behavior of the cracked area is monitored, with displacement and deformation fields acquired for each load increment. The obtained data is used to calculate fracture parameters, such as the Stress Intensity Factor (SIF). For that purpose, an overdeterministic algorithm was developed to calculate SIFs for each measured crack length. The main contribution of the present work is the adoption of a high-resolution optical contactless technique to monitor the fatigue crack tip. The obtained SIF values are compared to the reference solution proposed by ASTM E647 and an acceptable agreement has been verified. © 2022 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 Pedro Miguel Guimaraes Pires Moreira Keywords: ESPI; Fatigue; Fracture; Crack tip monitoring. E ICSI 2021 The 4th International Conference on Structural Integrity Electronic Speckle Pattern Interferometry for fatigue crack monitoring Behzad V. Farahani*, Frederico Direito, Pedro J. Sousa, Paulo J. Tavares, Pedro M. P. G. Moreira INEGI – Institute of Science and Innovation in Mechanical and Industrial Engineering, FEUP, R. Dr. Roberto Frias 400, 4200-465 Porto, Portugal.

1. Introduction The existence of cracks in structures and components subjected to fatigue loadings stimulates the necessity to

* Corresponding author. Tel.: +351 938096044 E-mail address: behzad.farahani@fe.up.pt

2452-3216 © 2022 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 Pedro Miguel Guimaraes Pires Moreira

2452-3216 © 2022 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 Pedro Miguel Guimaraes Pires Moreira 10.1016/j.prostr.2022.02.021