Analysis of cracked aluminum plates repaired with bonded composite patches

Bonded composite repair has been recognized as an efficient and economical method to extend the service life of cracked aluminum components. An accurate tool for investigating the stress intensity factor in the cracked aluminum structure after repair is needed. The use of three-dimensional finite elements is computationally expensive. A simple analysis method using Mindlin plate theory is presented. Specifically, the aluminum plate and composite patch are modeled separately by the Mindlin plate finite element, whereas the adhesive layer is modeled with effective springs connecting the patch and aluminum plate. Constraint equations are used to enforce compatibility of the patch-adhesive and adhesive-aluminum plate interfaces, Comparison of the present stress intensity factors for the aluminum crack with a plane boundary element analysis and a three-dimensional finite element analysis are made. A procedure for calculating the strain energy release rate along the debond front at the aluminum-adhesive interface is proposed.