Fatigue of cracked plates repaired with single-sided composite patches

Abstract

Fatigue of cracked plates repaired with single sided composite patches is studied via both analytical and experimental approaches. A finite element model, which considers out-of-plane bending effects induced by asymmetric repair, is presented to determine the crack tip opening displacements of the repaired plates subjected to in-plane loading. The modified crack closure technique is used to calculate the stress intensity factor of the repaired plates. Fatigue life of the repaired plates is studied via the use of Paris tan for crack propagation. The effects of cracked plate and composite patch thicknesses on the fatigue track propagation of repaired plates containing different types of cracks are investigated. Fatigue tests of aluminum C-T specimens repaired with single-sided composite patches are performed, and the test data are used to validate the analytical approach. It has been shown that the repair of a cracked plate with a single-sided composite patch may have beneficial or adverse effects on the fatigue life of the repaired plate depending on the thicknesses of the patch and the cracked plate.