PSI - Issue 54

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

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 54 (2024) 638–644

© 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 ICSI 2023 organizers Abstract In this work, two different high-resolution optical tools are used to measure in-plane displacements on the crack flanks close to the crack tip, which can then be used to determine the presence of crack closure in propagating fatigue cracks. Middle tension (MT) AA6082-T6 aluminum alloy specimens were used with an initial notch, submitted to a cyclic fatigue-loading to open the crack with a pre-determined length. Then, the cracked specimen is monotonically loaded, with defined load increments, to reach the peak load. Digital Image Correlation (DIC) and Electronic Speckle Pattern Interferometry (ESPI) are employed to collect the experimental data at different resolution, calculating the displacement and deformation fields while the specimen is statically loaded. The force-displacement variation on the vertical virtual gauges defined on the crack flanks adjacent to the crack tip is also meticulously monitored. Results from both techniques are compared, and a complementary multiscale methodology is proposed for the crack closure phenomenon. © 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 ICSI 2023 organizers International Conference on Structural Integrity 2023 (ICSI 2023) Multiscale Optical Methods to Measure the Fatigue Crack Closure Behzad V. Farahani * , Frederico Direito, Pedro J. Sousa, Paulo J. Tavares, Pedro Moreira INEGI - Institute of Science and Innovation in Mechanical and Industrial Engineering, Campus da FEUP, R. Dr. Roberto Frias 400, 4200-465 Porto, Portugal. Abstract In this work, two different high-resolution optical tools are used to measure in-plane displacements on the crack flanks close to the crack tip, which can then be used to determine the presence of crack closure in propagating fatigue cracks. Middle tension (MT) AA6082-T6 aluminum alloy specimens were used with an initial notch, submitted to a cyclic fatigue-loading to open the crack with a pre-determined length. Then, the cracked specimen is monotonically loaded, with defined load increments, to reach the peak load. Digital Image Correlation (DIC) and Electronic Speckle Pattern Interferometry (ESPI) are employed to collect the experimental data at different resolution, calculating the displacement and deformation fields while the specimen is statically loaded. The force-displacement variation on the vertical virtual gauges defined on the crack flanks adjacent to the crack tip is also meticulously monitored. Results from both techniques are compared, and a complementary multiscale methodology is proposed for the crack closure phenomenon. © 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 ICSI 2023 organizers International Conference on Structural Integrity 2023 (ICSI 2023) Multiscale Optical Methods to Measure the Fatigue Crack Closure Behzad V. Farahani * , Frederico Direito, Pedro J. Sousa, Paulo J. Tavares, Pedro Moreira INEGI - Institute of Science and Innovation in Mechanical and Industrial Engineering, Campus da FEUP, R. Dr. Roberto Frias 400, 4200-465 Porto, Portugal. 1. Overview Experimental techniques together with analytical methods play a substantial role in the field of fatigue and fracture mechanics. Modern technological developments in computer vision technology have made Digital Image Correlation (DIC) a dependable and robust tool to measure displacement and deformation fields at the surface of a cracked 1. Overview Experimental techniques together with analytical methods play a substantial role in the field of fatigue and fracture mechanics. Modern technological developments in computer vision technology have made Digital Image Correlation (DIC) a dependable and robust tool to measure displacement and deformation fields at the surface of a cracked Keywords: ESPI; DIC; Fracture Mechanics; Crack Closure; Fatigue Crack. Keywords: ESPI; DIC; Fracture Mechanics; Crack Closure; Fatigue Crack.

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

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 ICSI 2023 organizers 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 ICSI 2023 organizers

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 ICSI 2023 organizers 10.1016/j.prostr.2024.01.129