Theoretical-Experimental Model for Predicting Crack Growth Rate in Structural Alloys of Aircraft Gas Turbine Engine Disks with Regard to Fatigue and Creep

Hold times of 300 and 3600 s under trapezoidal cyclic loading are shown to result in an increase in crack growth rates by many factors of ten for EP962 alloy and several times for EP742 alloy at a temperature 973 K. It has been found that in case the creep crack growth diagram has a first segment where the crack growth rate decreases, the crack growth kinetics under trapezoidal cyclic loading can be predicted by means of the hypothesis of linear summation of fatigue and creep crack growth rates considering special features of the first segment of the creep crack growth diagram. The authors put forward empirical approaches to determining the mean rate on the first segment of the creep crack growth diagram. __________ Translated from Problemy Prochnosti, No. 6, pp. 15 – 25, November – December, 2005.