Analytical formulation of the stress intensity factor for crack emanating from central holes and repaired with bonded composite patch in aircraft structures

The determination of the stress intensity factor at the crack tip is one of the most widely used methods to predict the fatigue life of aircraft structures. This prediction is more complicated for repaired cracks with bonded composite patch. This study was performed in order to establish an analytical model for the stress intensity factor for repaired crack emanating from central holes. The model was developed by modifying that of Kujawski initially developed for cracks emanating from notch without repair. The obtained results were compared with those calculated with the finite element method and the model of Jones et al. It was found that our model gives a good approximation of the stress intensity factor for repaired crack emanating from central elliptical and circular holes if the results of the finite element analysis are taken as references.