The development of an ultra-high cycle bending vibration fatigue system on the basis of the mechanism of the fatigue failure of aeroengine vanes was discussed

including the design of ultra-high cycle dissymmetrical bending fatigue specimens.Research about TC17 was accomplished by the Ultra-High Cycle bending fatigue system (20 kHz).The fractograph of specimens was analyzed.The result indicates that the crack initiation is independent of interior inclusion and defect

and there are two kinds of mechanism of fatigue crack initiation:arising on surface or subsurface void.In addition

behaviors of interior crack initiation and propagation were not found the image of crack propagation is different from “fish-eye”.