LAUSR

Abstract Statistically representative programmed block renditions of a transport aircraft wing load spectrum were used to study cycle sequence effects on near-threshold fatigue crack growth rate. Less frequent higher load cycles served as markers that permitted unambiguous estimation of crack growth rate under individual load levels in the load spectrum. Small cycle crack growth rates down to threshold levels are extremely sensitive to the peak-valley sequence of preceding large load cycle, suggesting the need to model the effect of near-tip residual stress on threshold stress intensity in handling load spectra with a large statistical content of smaller load cycles.