Comparative analysis between co-curing and adhesive bonding of glass-epoxy composite laminates and AA5083 aluminium sheets for Maritime application: effect of surface pattern

Co-curing and secondary bonding are effective techniques to join not only composite structures but also dissimilar materials such as metals and composites whose combined use is increasing in several industrials fields where lightness is strategic to reduce fuel consumption and, consequently, greenhouse emissions (i.e. transports). In particular, the aim of this research is to investigate the effect of different patterns both on co-cured glass-epoxy composite/aluminium joints and on the same joints made with adhesive as third material to bond the aluminium and the laminate preliminary realized by vacuum infusion. These configurations and the materials to join were used typically in maritime applications, i.e. the composite can be used for the main deck and the aluminium for the superstructures. The patterns were made with a controlled milling machine equipped with an engraver with a 45° cutting angle. In both cases, the results showed that the mechanical treatment affected the mechanical properties, i.e. the joint with the best pattern had a higher mechanical strength than the joint where the surface was not treated. Moreover, this influence was more significant for co-curing. Finally, a statistical analysis was performed to evaluate the significance of both the selected factors: i.e. joining process and treatment, and their interaction. The novelty of the work lay both in the materials used to make the joints, which are employed in marine applications, in the use of macroscopic pattern to treat the metal surface for co-cured joints, and in the manufacturing process, which used a CNC milling machine.