Fatigue Behavior of Composite Patch Repaired Aluminum Plate

Abstract

Experimental and analytical studies are conducted to characterize the fatigue crack growth behavior of precracked aluminum plates repaired with asymmetric bonded composite patch. For single-sided repairs, due to the asymmetry and the presence of out-of-plane bending, crack front shape would become skewed curvilinear starting 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 and consider the actual crack front shape evolution for the accurate analysis of fatigue behavior. Nevertheless, in most previous studies, crack front has been modeled as a uniform straight one, which may cause inaccuracy. In this study, the actual crack front evolution is predicted and considered in estimating the fatigue life by implementing the successive analysis technique based on the three-dimensional finite element scheme. Experimental tests with various plate thicknesses (2, 4, 6, 8, and 10 mm) are also carried out to verify the present approach. The analytical predictions of both the crack front shape evolution and the fatigue life are in good agreement with the experimental observations. By both experimental and analytical approaches, the characteristics of the fatigue crack growth behavior and the effectiveness of single-sided repairs according to the plate thickness are investigated.