Investigation of fully variable fatigue performance of joints bonded with nano-structure reinforced composite adhesive

Bonding joints used in the aerospace and automotive industries are often exposed to dynamic and environmental influences rather than static loading. It is very important to improve the performance of bonded joints exposed to dynamic and environmental influences. In this study, both fully variable tensile and four-point bending post fatigue mechanical properties of the single-lap joint obtained by adding carbon nanostructures into the adhesive to improve the fatigue strength of the structural adhesive used in the aviation field were experimentally investigated. By using 1% by weight of Graphene, Carbon Nanotube-COOH and Fulleren C60 nanostructures, a single effect lap joint was produced using the nanocomposite adhesive. AA2024-T3 aluminum alloy and carbon fiber reinforced composites, which are frequently used in aviation, are used as bonding materials. Static draft load was applied to these produced connections and damage loads were obtained. Then, sinusoidal waveform, constant load amplitude, 20 Hz frequency and R = -1 loading ratio were applied to these joints with fully variable tensile and four point bending fatigue test. By obtaining the static tensile failure load of these joints on which fatigue load is applied, the change in the failure load of the joints that are exposed to fatigue and not have been examined. As a result of the work carried out; compared to nanostructured joints, it has been observed that the static performances of nanostructured joints increase after fully variable fatigue. In addition, these increase rates in damage loads vary depending on the type of nanostructure added to the adhesive and the type of material bonded.