Buckling fatigue behavior of 2A97 Al-Li alloy stiffened panels under shear loading

Abstract

In order to study buckling fatigue behavior and failure modes of 2A97 Al-Li alloy stiffened panels under shear loading, 1.2 mm and 1.5 mm thick 2A97 Al-Li alloy stiffened panels were designed and manufactured. The static and fatigue tests were performed under shear loading. The results indicate that the shear failure modes of stiffened panels are global buckling wave, skin cracks and rivets falling off. The effect of skin thickness on the buckling load is greater than that on the ultimate load. The fatigue failure processes of stiffened panels include gradual failure and catastrophic failure. The fatigue failure modes are complex and rivet falling off is most dangerous. Panels with cracks or broken rivets still has residual life. Once the skin tears, the panel will immediately fail. The total fatigue life and initial fatigue life of 1.5 mm stiffened panel are 28.87% and 59.88% higher than those of 1.2 mm stiffened panel respectively, while the residual life is 87.68% lower. The finite element models were established to simulate the buckling and post-buckling process of the stiffened panels, and the local stress spectrum of the fatigue dangerous point was obtained. Goodman's theory and nominal stress method was combined to predict the fatigue life and to explain the experimental findings.