The influence of service and manufacturing defects on cyclic life of gas turbine engine blades

Fatigue tests of turbine rotor blades with manufacturing defects and compressor rotor blades with notches simulating in-set-vice defects were performed. It was shown that in the presence of manufacturing defects the scatter of fatigue characteristics of turbine blades increases. The defects which have the biggest effect on fatigue characteristics of turbine blades at room and operating temperatures were determined. For compressor blades of various types the sizes of the defects which have no influence on their fatigue limits were defined. This is associated with the pattern of stress distribution along the blade length., Allowable defects in compressor rotor blades should be defined experimentally due to possible changes in the oscillation mode of blades with defects. Design engineers should take into account the regularities found in their calculations of the reliability and lifetime of blades.