Effect of Disbonding Between a Composite Patch and a Cracked Aluminum Plate on the Stress Intensity Factor

Bonded composite patch repairs to metallic structures is receiving increased attention in the recent years. It offers various advantages over rivetted doubler, particularly for airframe repairs. This article presents the crack growth behavior of an edge cracked aluminum plate repaired using boron/epoxy composite patch. The effect of the size and location of this disbond on the tensile behavior of the repaired plate is investigated. An analysis procedure, involving finite element modeling of the cracked plate, adhesive, and composite patch, is conducted to compute the stress intensity factor. The results indicate that the crack growth rate is dominated by the stress intensity factor and the size of the pre-existing disbonds. Cracking of the plate and propagation of the disbond results in an increase in the patch deformation.