Stochastic crack propagation in fastener holes

A simple crack growth rate-based stochastic model for fatigue crack propagation in fastener holes under spectrum loadings is investigated. With available fractographic data in the very small crack size region, i.e., 0.004 to 0.07 inches, the model was demonstrated previously to be very good. Further, laboratory tests were conducted using wide fastener hole specimens to obtain fractographic data covering the small and large crack size regions in both laboratory air and a corrosive environment. The correlations between the stochastic model and the fractographic results in either the corrosive or noncorrosive environment are demonstrated to be very good. The model is shown to be valid for crack growth damage accumulation from the very small crack up to the critical crack size. Such a simple model is ideal for practical applications, such as in durability and damage tolerance analyses. Factors affecting the stochastic crack growth analysis and prediction are also investigated.