Cyclic-inelastic deformation and fatigue resistance of notched-thin aluminum plates

The results of experiments designed to develop data to assess the accuracy and utility of the critical location concept in applications of fatigue-crack nucleation analysis at notch roots are presented and discussed. Fully reversed and nonzero mean-stress data are presented over a range of lives which encompass both elastic and inelastic deformations for thin-notched specimens and smooth specimens made of 2024 T351 aluminum-alloy sheet. Notch-root strains were measured via an extensometer, whereas the formation of small cracks was detected via an eddy-current transducer. Data reported indicated the validity of the assumption that smooth and notched specimens form cracks at the same cycle number when identical deformation histories are imposed at their respective critical locations. They also serve to demonstrate the accuracy and utility of the critical-location approach in analysis to predict the formation of small cracks at notches in coupons and components.