The influence of epoxy adhesive toughness on the strength of hybrid laminate adhesive joints

The use of composite materials in structural applications has significantly expanded in recent years. The transport industry accounts for an increasingly larger share of the final structural weight of vehicles, as manufacturers pursue improvements in fuel economy, lighter more efficient designs, and reduction of emissions. However, the delamination of adhesively bonded composite joints causes premature failure of the bond, inhibiting the use of its full potential and leading to inefficient and over-designed components. A hybrid composite metallic material technology is studied in this work, a method inspired in the fibre metal laminate concept, and which combines the best properties of FRPs and metal alloys. The hybrid composite-metallic adherends aims to increase the joint strength in the through thickness direction, minimise peel stresses and limit delamination. The objective of this work was to evaluate the performance of hybrid joints, bonded with different adhesives by comparing them against a reference joint using a conventional Carbon fibre reinforced polymer (CFRP) adherend. The joints were experimentally tested using a universal testing machine for a crosshead speed of 1?mm/min. Numerical models were developed, using the ABAQUS software, to study the behaviour of all joints studied. The numerical predictions of failure loads and modes were compared to the experimentally obtained results.