Study of composite patch repair by analytical and numerical methods

A combined analytical and numerical study of an isotropic cracked plate that was repaired by using a bonded composite patch was conducted. The analytical work was based on Rose's equations, whereas for the numerical investigation a three-dimensional finite element analysis was implemented. A number of cracked plates with different crack lengths and overall dimensions of the composite repair were considered. The composite patch was made of unidirectional laminates with different stacking sequences. Both, one- and two-sided patches were analysed. Results are presented for the stress intensity factor in the patched crack and the maximum stress reinforcement stress and adhesive strain. It was found that for the case of a two-sided reinforcement the results obtained by both methods were in good agreement. However, for the case of a single reinforcement the accuracy of the analytical method decreased due to the tendency to out-of-plane bending as a result of bonding a reinforcing patch to only one face of a plate, which is ignored in the analysis.