PSI - Issue 47

Available online at www.sciencedirect.com 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 ScienceDirect

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Procedia Structural Integrity 47 (2023) 176–184

© 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 IGF27 chairpersons The resistance signal was recorded in real-time to monitor fatigue damage. The effect of the variation in electrical resistance due to thermal contribution was eliminated monitoring the temperature during test. Experimental resistance measurements showed a reduction due to self-generated heat in the early stages of the test due to load cycles. Subsequently, from about 5-30 % of the fatigue life, the resistance shows a progressive rapid increase due to the degradation of the material and the evolution of the damage. Starting from about 60-70 % of the fatigue life, the resistance undergoes a further rapid increase corresponding to delamination. The latter behavior is coherent with the stiffness degradation. The results obtained were compared with the thermal data, expressed through appropriate damage parameters, to study the possible correlations in the prediction of fatigue damage. © 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 IGF27 chairpersons Keywords: CFRP, fatigue damage, electrical resistance, thermography, Structural Health Monitoring (SHM) 1. Introduction Fatigue is the most frequent failure mechanism that occurs in critical mechanical components subjected to time varying loads and the evaluation of their structural integrity for the entire service life is an important goal to be achieved (Palit Sagar et al. (2006)). In the literature, many researchers have proposed different methods to study these Abstract In this work, Non-Destructive Techniques were used to study the fatigue behavior of a batch of aeronautical specimens in CFRP, obtained by Liquid Resin Infusion (LRI) process, subjected to fatigue with different stress levels. The resistance signal was recorded in real-time to monitor fatigue damage. The effect of the variation in electrical resistance due to thermal contribution was eliminated monitoring the temperature during test. Experimental resistance measurements showed a reduction due to self-generated heat in the early stages of the test due to load cycles. Subsequently, from about 5-30 % of the fatigue life, the resistance shows a progressive rapid increase due to the degradation of the material and the evolution of the damage. Starting from about 60-70 % of the fatigue life, the resistance undergoes a further rapid increase corresponding to delamination. The latter behavior is coherent with the stiffness degradation. The results obtained were compared with the thermal data, expressed through appropriate damage parameters, to study the possible correlations in the prediction of fatigue damage. © 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 IGF27 chairpersons Keywords: CFRP, fatigue damage, electrical resistance, thermography, Structural Health Monitoring (SHM) 1. Introduction Fatigue is the most frequent failure mechanism that occurs in critical mechanical components subjected to time varying loads and the evaluation of their structural integrity for the entire service life is an important goal to be achieved (Palit Sagar et al. (2006)). In the literature, many researchers have proposed different methods to study these 27th International Conference on Fracture and Structural Integrity (IGF27) Fatigue damage prediction of CFRP specimens by means of Non Destructive Techniques R. Nobile a , F. W. Panella a , A. Pirinu a , A. Saponaro a, * a University of Salento – Department of Engineering for Innovation, Via per Monteroni, 73100 Lecce, Italy Abstract In this work, Non-Destructive Techniques were used to study the fatigue behavior of a batch of aeronautical specimens in CFRP, obtained by Liquid Resin Infusion (LRI) process, subjected to fatigue with different stress levels. 27th International Conference on Fracture and Structural Integrity (IGF27) Fatigue damage prediction of CFRP specimens by means of Non Destructive Techniques R. Nobile a , F. W. Panella a , A. Pirinu a , A. Saponaro a, * a University of Salento – Department of Engineering for Innovation, Via per Monteroni, 73100 Lecce, Italy

* Corresponding author. Tel.: +39 0832 297786; fax: +39 0832 297768. E-mail address: andrea.saponaro@unisalento.it * Corresponding author. Tel.: +39 0832 297786; fax: +39 0832 297768. E-mail address: andrea.saponaro@unisalento.it

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 IGF27 chairpersons 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 IGF27 chairpersons

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 IGF27 chairpersons 10.1016/j.prostr.2023.07.009