Fracture Analysis of the 2nd Stage Compressor Blade in an Aeroengine

The blades on the 2nd stage compressor of one kind of aeroengine are frequently damaged components.Recently a fault of blade body fracture happened,which is different from the usual blade corner fracture.Judging from the shape of the fractured blade,it is a new type of fault,which is different from the corner fracture caused by the 2nd twist vibration.The fatigue started from the upper middle of the blade.The resulted crack expanded vertically up and down,and then turned horizontally in different directions.Finally,the upper part of the blade flew away.The flown part is about one third of the whole blade and the fracture shape is of "S" form.This paper provides an analytical conclusion drawn from the research work including:metallographic analysis of the blade fracture,scanning electron microscope analysis,computation and analysis of the vibration characteristics,the measurement of the static frequency and vibration mode of the blade,the test of fatigue breach,the measurement of the 10th relative vibration stress,and estimating of the fatigue life-time of the blade.The paper concludes that the mechanism of this new type fault is the 10th vibration of the blade,which occurred at 0 8 rating rotation of the aeroengine and the basic cause is the resonance and the flaw of the blade basin surface.