Issue 46

N. C. M. Ibrahim et alii, Frattura ed Integrità Strutturale, 46 (2018) 140-149; DOI: 10.3221/IGF-ESIS.46.14 140 Developments in the fracture and fatigue assessment of materials and structures Analysis of the crack-crack interaction effect initiated in aeronautical structures and repaired by composite patch Nour Chafak Mohamed Ibrahim, Serier Boualem, Mechab Belaïd University of Djillali Liabes, LPMM Laboratory, Sidi Bel Abbes, Algeria nor_achafak@yahoo.fr , serielem@ yahoo.com, bmechab@yahoo.fr A BSTRACT . In this work, we analyze three - dimensionally, by the finite element method, the performance of the repair of aeronautical structures damaged by cracking and repaired by patch of composite materials. The effect of crack-crack interaction according to their position and interdistance was analyzed. The criterion of rupture retained for this study is the factor of intensity of constraints. We show that this factor increases considerably and reaches a critical threshold when the two cracks develop towards each other. The repair of such damage using a composite patch ensures the stability of this structure during the commissioning process. The sharp fall in the stress intensity factor is characteristic of this stability. K EYWORDS . Plate; Repair; Adhesive; Patch; Composite materials; Crack; Finite elements; Stress intensity factor. Citation: Ibrahim, N. C. M., Serier, B., Mechab, B., Analysis of the crack-crack interaction effect initiated in aeronautical structures and repaired by composite patch, Frattura ed Integrità Strutturale, 46 (2018) 140-149. Received: 05.06.2018 Accepted: 12.07.2018 Published: 01.10.2018 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 echniques for repairing and reinforcing damaged structures by bonding composite patches are increasingly used in industry, with the aim of delaying the appearance or propagation of fatigue cracks. In this technique, a composite patch is assembled to the damaged part with an adhesive, the aim of which is to transmit the maximum of stresses of the plate to the patch through the adhesive in order to reduce them to the Tip of the crack. The notches are the main cause of the initiation of the crack and thus the repair with composite patches can play an important role, on the other hand, in reducing the stress concentration at the tip of the crack, And on the other hand of the reduction of the intensity of the stresses at the crack tip. Therefore, the bonding assembly has several advantages, the possibility of assembling different materials, weight reduction, high stiffness, good fatigue strength, shock reduction and ease of bring together the most complex shapes. This technique has been extensively studied, where the stress intensity factor is considered an important factor in estimating the residual lifetime of cracked structures. In order to improve this technique, several experimental, numerical and even analytical studies have been devoted to the study of this behavior. The work was launched, in 1984, by Baker at the Australian Research Laboratory ARL. [1, 2]. Analytically, several works have been devoted to understanding this class of problems represent the effect of the patch on the crack tip stress intensity factor such as, Mitchell and al. [3], Jones and Callinan [4], Rose [5 - 7], Young and al. [8, 9], Rooke and al [10], Ramesh Chandra and al., [11] Liu and Fan [12], Arendt and Sun [13]. Numerically, several authors have shown that the stress intensity factor depends on several parameters, the size and position of the crack, the patch and adhesive dimensions, the T