Mechanical analysis of unidirectional glass fibre reinforced epoxy composite joints manufactured by adhesive bonding and co-curing techniques

The use of epoxy powder in composite laminate fabrication may provide an efficient and alternative solution to traditional resin infusion techniques for manufacturing thick and complex composite parts in the aerospace, automotive, and marine industries. This study demonstrates the feasibility of this technology for joining of unidirectional glass fibre-epoxy composite parts with desired mechanical strength through co-curing process. The effectiveness of co-curing techniques for joining thin and thick composite laminates were assessed and compared with adhesive joints. The challenges and parameters relating to both manufacturing methods were discussed. The results showed that co-curing bonding is an effective bonding method alongside adhesive joints. The co-curing joints showed a 49% higher shear strength than optimised adhesive joints. To further demonstrate the effectiveness of the results, one beam, with co-curing and adhesive bonding joints, was manufactured as a demonstrator of a bowfoil. The beam was then tested under four-point bend tests to characterise the flexural strength and damage propagation area. The results revealed that both bonding types withstand the ultimate loads, with the composite part failing. A finite element model was proposed, and its accuracy was verified against the test results, with an average difference of 8.9% in ultimate fibre direction strain.