Predicting the effect of residual stress on fatigue crack growth

Fatigue crack growth from a hole with a pre-existing compressive residual stress is simulated using two-dimensional elastic–plastic finite element analyses. The analyses allow a determination of the crack opening stress as the crack propagates through the residual stress, from which the effective stress intensity factor range ΔKeff and the fatigue crack growth is predicted. Results from these simulations are compared with experimental data and to predictions made using a conventional superposition of the elastic stress intensity factor. The crack closure-based methodology resulted in predictions which compared well with the experimental data, while the results using superposition were nonconservative. Predictions from the closure-based method are highly dependent on the da/dN = f(ΔKeff) constitutive relationship used, highlighting the need for experimental methods to reliably measure this correlation.