Fatigue crack growth with retardation under stationary stochastic loading

The crack propagation under Gaussian stationary stochastic loading in presence of crack growth retardation effects is considered. The Wheeler retardation model is applied. The crack growth process is modeled by Markovian diffusion process. Some properties of envelope and clustering effect of the load process are taken into account in calculation of parameters of the Kolmogorov diffusion equation. The mean time to failure when the crack reaches its critical length is determined. The analysis of the mean lifetime equation and results of an example show that the stochastic fluctuations of the stationary load process alone do not affect significantly random variations of the lifetime. A quasi-deterministic relation between the features of the fatigue fracture and some material and load parameters is proposed. It gives a potential to consider effectively the fatigue crack propagation with retardation effects as an additional failure mode in reliability analysis.