This paper discribes the damage tolerance analysis of compressor blade by fracture mechanics.Finite element method with 20 nodes solid elements is used for the stress calculation.A displacement method is provided to determine the stress intensity factors K Ⅰ

K Ⅱ and K Ⅲ versus crack length a of the blade.Based on the material toughness K ⅠC

additional extension δ c and deviation of natural frequency f c of the cracked blade

the failure criterion of the compressor blade is discussed and the critical crack length is determined.By the use of Pris formula and in consideration of the influence of high cycles on low cycle fatigue crack propagation

the damage tolerance life of the blade is obtained.As an example

a calculation of a certain compressor blade is given.In order to investigate the relation of natural frequency versus crack length

the vibration of compressor blades has been tested.The presented method can be used for the strength evaluation of turbo jet engine.