某型发动机二级压气机叶片断裂故障分析研究

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

某型发动机二级压气机叶片属于事故多发性零部件。最近又发生了叶身断裂故障 ,该故障是一种新型故障 ,与二扭共振引起的叶尖掉角故障不同 :疲劳源位于叶盆中上部 ,靠近叶尖断裂飞出 ,断裂飞出部分约为叶片的 1 /3,故障件断口部分呈“S”型。本文从叶片断口金相、扫描电镜分析、振动特性计算分析、叶片静频和振型测量、疲劳破坏试验、第 1 0阶相对振动应力测量和叶片疲劳寿命评估等研究工作 ,分析得出造成叶片疲劳破坏的故障机理是叶片第 1 0阶振型在发动机 0 .8额定转速发生共振和叶盆表面损伤。

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.