TIME-DEPENDENT CRACK-GROWTH CHARACTERIZATION USING RATE INTEGRALS

Abstract

This paper investigates the utility of the rate forms of Kishimoto et al.'s integral ((J) over cap) and Blackburn's integral (J*) as parameters for correlating time-dependent crack growth rates. These rate integrals are computed from the results of finite element analyses of crack growth in button-head single edge notch specimens of Alloy 718. The specimens are tested under constant strain and constant load conditions at 593 degrees C and 649 degrees C. The crack tip deformation includes large-scale plasticity, primary and secondary creep. The measured crack growth rates are correlated with the computed rate integrals. The results show that both integrals can consolidate the crack growth data very well.