PSI - Issue 52

ScienceDirect Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2022) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2022) 000–000 Available online at www.sciencedirect.com Procedia Structural Integrity 52 (2024) 600–610

www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

© 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 Professor Ferri Aliabadi Abstract A novel approach for the determination of the initiation of mixed mode delamination crack on glass/epoxy DCB specimens is presented. In the present study, acoustic emission measurements were used to identify the onset of delamination using different signature acoustic emission features. The acoustic emission was also utilised to track the crack front during all tests. Both, the acoustic emission features, as well as the crack front localisation indicate two different regions denoted as region I, and region II. It was observed that the cumulative sum of the acoustic emission features in region I shows a slow increase (both in the AE features and in the crack front localization), whereas in region II there was a rapid increase on acoustic emission and a progressive advance of the crack front. Furthermore, the initiation as obtained from the acoustic emission measurements was used to define and calibrate a new simpler approach for the determination of mixed-mode delamination crack initiation. The new approach, which is both faster and simpler, is based on the deviation from linearity of the load (or moment) vs displacement curve. Keywords: Crack initiation; Accoustic Emission; Delamination; Mixed mode fracture Abstract A novel approach for the determination of the initiation of mixed mode delamination crack on glass/epoxy DCB specimens is presented. In the present study, acoustic emission measurements were used to identify the onset of delamination using different signature acoustic emission features. The acoustic emission was also utilised to track the crack front during all tests. Both, the acoustic emission features, as well as the crack front localisation indicate two different regions denoted as region I, and region II. It was observed that the cumulative sum of the acoustic emission features in region I shows a slow increase (both in the AE features and in the crack front localization), whereas in region II there was a rapid increase on acoustic emission and a progressive advance of the crack front. Furthermore, the initiation as obtained from the acoustic emission measurements was used to define and calibrate a new simpler approach for the determination of mixed-mode delamination crack initiation. The new approach, which is both faster and simpler, is based on the deviation from linearity of the load (or moment) vs displacement curve. Keywords: Crack initiation; Accoustic Emission; Delamination; Mixed mode fracture Fracture, Damage and Structural Health Monitoring Determination of Mixed Mode Delamination Crack Initiation using Acoustic Emission Measurements Ruben I. Erives a, *, Ashish K. Bangaru a , Malcolm M. Gugan a s a Department of Wind and Energy Systems, Technical University of Denmark, DTU Risø, Frederiksborgvej 399, 4000 Roskilde, Denmark Fracture, Damage and Structural Health Monitoring Determination of Mixed Mode Delamination Crack Initiation using Acoustic Emission Measurements Ruben I. Erives a, *, Ashish K. Bangaru a , Malcolm M. Gugan a s a Department of Wind and Energy Systems, Technical University of Denmark, DTU Risø, Frederiksborgvej 399, 4000 Roskilde, Denmark

Nomenclature δ n Nomenclature δ n δ t δ δ 0

normal end-opening tangential end-opening effective crack end-opening end-opening at crack onset effective crack end-opening end-opening at crack onset normal end-opening tangential end-opening

δ t

δ

δ 0

* Corresponding author. E-mail address: riea@dtu.dk

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 Professor Ferri Aliabadi 10.1016/j.prostr.2023.12.060 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 Professor Ferri Aliabadi 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 Professor Ferri Aliabadi * Corresponding author. E-mail address: riea@dtu.dk