Blade for a gas turbine engine comprising composite material having voids configured to act as crack initiation points when subject to deformation wave

Abstract

Blades for gas turbine engines which are formed from composite materials have problems with respect of resistance to impacts such as bird strikes. Previous blades formed from metals had some ductility towards the trailing edge which could accommodate the whiplash effects of impacts. With regard to composite materials such ductility is not present. By providing projectionswhich act as propagation wave trips as well as high intensity reflectorsit is possible to limit the whiplash at the edgeresulting in damage. Typically a cladding capis provided which also may be formed from a metal to allow some greater uniformity with respect to mass per length despite the tapering of the blade. Furthermore by providing voids which act as delamination initiation sites cracking can be provided between plies which allows greater flexibility towards the edge and therefore release of energy. These voids may incorporate uncured polymer matrix to act as a binder subsequent to delamination.