Fibre Composite Repair of Cracked Metallic Aircraft Components

Crack patching, the use of advanced fibre composite patches (such as boron/epoxy or graphite/epoxy) bonded with structural film adhesives to repair cracks in metallic aircraft components, is a significant development in aircraft maintenance technology, offering many advantages over conventional repair procedures based on metallic patches and mechanical fasteners. This paper reviews selected theoretical and experimental aspects of Australian work on this topic and describes a preliminary design approach for estimating the minimum thickness patch that could be employed in a given repair situation. Aspects discussed include evaluation of minimum cure and surface-treatment conditions for adhesive bonding in repair situations; potential thermal and residual stress problems, resulting from patching; studies on overlap joints representing repairs and crack propagation behaviour in patched panels.