Successive 3D FE analysis technique for characterization of fatigue crack growth behavior in composite-repaired aluminum plate

An analytical approach using successive finite element analysis technique was conducted to characterize the fatigue crack growth behavior of pre-cracked aluminum plates reinforced with composite patches. For single-sided repairs, due to the asymmetry and the presence of out-of-plane bending, crack front shape would become skewed curvilinear started from a uniform through-crack profile, as observed from previous studies. As the stress intensity factor (SIF) calculated at the crack tip is much influenced by crack front shape, it is necessary to predict the actual crack front shape evolution and take it into account for the accurate analysis of fatigue behavior. Present procedure performed a three-dimensional geometrically nonlinear finite element analysis to determine the SIF distribution at a set of points along the crack front, and then estimated the crack growth increments at these points by invoking a fatigue crack growth rate relationship (power-law relationship). A new crack front was then established for the next step by using a relevant remeshing scheme. Through conducting this procedure successively, the crack path of the patched plate as well as the fatigue life was evaluated with sufficient accuracy. The analytical predictions of both the crack front shape evolution and the fatigue life were in good agreement with the experimental observations.