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An analysis has been conducted to determine the feasibility of composite fan blade for meeting impact resistance requirements for turbo-fan engines. This report describes the effect of centrifugal force on the impact response of fan blades. Transient deformations of six fan blade models of different materials and sizes generated by bird strike were calculated by finite element method. It was cleared that global deformation of the blade made of heavy material was appreciably reduced by centrifugal force, but the effect of centrifugal force on the local deformation was small. For the blade made of light materials, e.g. polymer matrix composites, the effect of centrifugal force is less appreciable than for the blade made of heavy materials. Maximum stress generated by 1.5 lb (680 gram) bird strike is large enough to generate local permanent deformation in the metal blades and to generate global delamination in the polymer matrix composite blades.

A geometrically nonlinear finite element analysis of flexural edge waves for the composite jet engine fan blade model is presented. For the transient response problem of the composite fan blade subjected to local impact loading with foreign objects, existence of flexural edge wave in the region of the leading edge and the trailing edge was confirmed for the first time in computer simulation. Amplitudes of edge wave decrease exponentially with distance from the edge. These waves have dispersive characteristic even at low frequencies and are important in the region of the leading edge and the trailing edge of composite blade structures. It was found that delaminations of the leading edge in experimental results for ATP (Advanced TurboProp) blade model presented in the literature were related to this edge wave propagation along the free boundary. And also it was clear that just after the impact, higher order flexural waves are generated owing to local deformations.