Fatigue failure of nuclear pressure vessel steels—II. Prediction of fatigue crack propagation

An approximated analytical solution relating to the stress-strain-state (SSS) near the crack tip at cyclic mixed loading was obtained. Analysis of conditions for damage accumulation in a material for gradient stress and strain fields was performed. A fatigue crack propagation model was developed on the basis of the local stress-strain criterion of fatigue failure formulated in a preceding paper (Part 1) and the analytical solution of the problem of the stress-strain-state near the crack tip. It was shown as applied to nuclear pressure vessel steel 2CrMoNiV that the proposed model allows one to predict the fatigue crack growth rate at any loading asymmetry and arbitrary ratio of stress intensity factors of I and II modes. Moreover, the model gives an adequate prediction for the beginning of the spasmodic growth of a fatigue crack.