Fatigue crack propagation through adhesively bonded stiffened panels: a model to describe the skin crack behavior underneath the stiffeners

Adhesively bonded stiffened panels can provide the best damage tolerance proprieties if compared to the conventional integral and riveted panels. Bonded panels can, indeed, take big advantage by the long fatigue crack propagation periods through the skin underneath the bonded stiffeners. To exploit the aforementioned benefit of bonded panels for safe and weight effective structures, reliable prediction models taking into account the fatigue crack propagation under the bonded stiffeners have to be provided. A well known analytical literature model, developed for the damage tolerance characterization of patch repairs, was implemented and subsequently validated by fatigue crack propagation test results concerning wide stiffened panels. The implemented model confirmed to be a reliable and effective method for the damage tolerance design optimization of thin-walled bonded structures.