Fatigue crack growth in patched plates under constant amplitude and flight simulation loadings\ud

Fatigue crack propagation was studied in aluminium alloy\ud plates reinforced by adhesive bonding a unidirectional carbon\ud fibre epoxy patch across the crack path. The tests were\ud carried out under constant amplitude as well as flight\ud simulation combat aircraft spectrum loading. Comparative\ud tests were also conducted on unpatched plates. The composite\ud patch considerably reduces crack growth rates. The improvement\ud in resistance to fatigue crack growth is more pronounced under\ud spectrum loading conditions