Analyses of XFEM and VCCT for Fatigue Crack Propagation in Thick Cracked Panels Repaired With CFRP Composites

ABSTRACT AA7075‐T6 aluminum alloy panels with damaged and thick surface layers were examined for their fatigue life with composite patches. Simulations using finite element software were conducted to analyze stress and crack propagation stages. Two models of uniform and skew crack fronts fatigue crack growth were implemented by combining XFEM and VCCT methods on the plates repaired with composite patches based on the Paris equation. The available experimental results and numerical simulation results are strongly correlated according to the comparison. To determine fatigue crack propagation path and fatigue crack propagation life, XFEM and VCCT simulation methods can be used for cracks in thick panel repairs with composite patches. In addition, the Paris equation can be used to determine fatigue cracks propagation path and fatigue crack propagation life. An increase of over 317% in fatigue life was achieved by applying composite patching to the cracked thick panels in the study. Based on the experimental results, the fatigue crack growth curve of the skew crack front model was similar to those obtained by the conventional uniform crack front models; however, the skew crack front fatigue life prediction was more accurate. This study specifically focused on evaluating crack propagation behavior in thick panels with single‐sided composite patches, which represents a common but challenging repair configuration in aerospace applications.