Issue 43

F.Z. Seriari et alii, Frattura ed Integrità Strutturale, 43 (2018) 43-56; DOI: 10.3221/IGF-ESIS.43.03 43 Fatigue crack growth of composite patch repaired Al-alloy plates under variable amplitude loading Fatima Zohra Seriari, Mustapha Benachour University of Tlemcen, Ingeniery of Mechanical Systems and Materials Laboratory, Tlemcen, Algeria fsdoctorat@gmail.com , bmf_12002@yahoo.fr Mohamed Benguediab University of Sidi Bel Abbes, LMPM Laboratory, Sidi Bel Abbes, Algeria benguediab_m@yahoo.fr A BSTRACT . In this paper, fatigue crack growth of edge crack in 2024 T351 aluminum alloy plate repaired with bonded composite patch under constant and variable amplitude loading (VAL) was predicted. The Al-alloy plate was repaired with symmetric patch “Boron/Epoxy”. Additionally to constant amplitude loading (CAL), the effects of single overload and band overload were investigated for repaired and unrepaired Al-alloy plates. The obtained results confirm the improvement in repair performances by composite patch on fatigue lives and crack growth rates for all applied cycles (CAL and VAL) compared to unrepaired plates. A retardation effect was observed in application of single overload compared to band overload with the same stress ratio (R=0.2) for unpatched plate and characterized by instantaneous delays. However, this retardation effect is increased by the presence of the patch repair which leads to the higher fatigue life. Retardation effect was neglected for lower overload ratio (ORL>1.8). Comparison in fatigue life and crack growth rates under the same overload ratio (ORL=2.4) between repaired and unrepaired plates show the supplementary beneficial effects in combination of overloading and patch repair K EYWORDS . Fatigue crack; Composite patch repair; Variable amplitude loading; Retardation; Al-alloy. Citation: Seriari, F.Z., Benachour, M., Benguediab, M., Prediction of fatigue crack growth of composite patch repaired Al-alloy plates under variable amplitude loading, Frattura ed Integrità Strutturale, 43 (2017) 43- 56. Received: 08.08.2017 Accepted: 03.10.2017 Published: 01.01.2018 Copyright: © 2018 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION s a consequence, fatigue problems become an important topic for the maintenance of damaged aircrafts structures. Bonded composite patch repair presents an advanced technology to reinforce damaged metallic of theses [1-3]. The crack patching bonding technique goes back to the 1980s, when it was successfully applied to A