Fatigue analysis of crack propagation in structures with bonded composite repair

Recent growth in the aeronautical and oil industries has increased the demand for efficient repair techniques that offer shorter maintenance periods, greater durability, and reduced costs. Bonded composite repairs have emerged as an excellent solution, enabling the restoration of components without compromising structural integrity. By the first attempt, the coupling of the 3D boundary element method (BEM) coupled to the generalised energy failure criteria is used for analysing crack propagation and fatigue life in structures with bonded composite repairs. This criterion is based on strain energy density concept. Initially, crack propagation for bonded single lap joint (SLJ) and bonded double cantilever beam (DCB) served for experimental validation of the numerical approach. Experimentally, fatigue tests were performed to evaluate crack propagation using digital image correlation (DIC), and the repair debonding via an unidirectional laser vibrometer. Comparing numerical and experimental results revealed that incorporating the failure of the adhesive in the simulation setup improves the accuracy over those models in the literature that consider only the failure of the plate.