Normalized strength reserve principle for variable amplitude fatigue life prediction of adhesively bonded aluminium joints/Normalisiertes Festigkeitsreserve-Prinzip für die Vorhersage der Lebensdauer von geklebten Aluminiumverbindungen bei variablen Lastamplituden

Over the last several decades, adhesive bonding has been validated as a good alternative to traditional joining methods in metallic construction. On the other hand, the main factor that limits the wider use of structural adhesives in civil engineering industry is scepticism about their long-term performance, especially when subjected to variable amplitude fatigue loading. Most of the research on predicting the fatigue life of adhesive joints subjected to this type of loading dealt with composite adherends. In this paper, straightforward method for prediction of strength degradation and fatigue failure under random spectrum loading is presented and validated for the case of adhesively bonded single lap joints made of aluminium adherends. It is based on the normalized strength reserve principle, proposed by the same authors in their previous research. The normalized strength reserve model is expanded to the case of variable amplitude fatigue, incorporating the cycle mix parameter in order to account for load interaction effects. Very good agreement was obtained between the fatigue life predictions of the presented method and experimental results from the literature.