Inelastic FE Analysis for J-Integral of Center-Cracked Plate in Creep-Fatigue Range

In order to estimate crack growth rate, it is necessary to use increments of the J-integral for both of time-independent fatigue process and time-dependent creep process. Many researchers and methodologies use C* to characterize creep crack growth and ΔJ or ΔK for fatigue crack growth, suggested are the following Refs.[1,2] This paper shows the fundamental features of J-integral in elastic, plastic and creep range. The path dependency is studied for center-cracked plate by using path integral from the large path to the small path near crack tip. The inelastic FE analysis is carried out for creep-fatigue loading, where the tensile strain is held constant to receive creep damage, and this paper shows the J-integral according to the loading histories. Also discussed are effects of the strain rate in fatigue process to affect the successive creep behavior.