An experimental investigation of static load capacity of AL-GFRP adhesively bonded single lap and double butt lap joints

This paper is focused on experimental evaluation and comparison of progressive damage behaviors in adhesively bonded single lap and double butt lap joints between aluminum and glass fiber reinforced plastic (GFRP). The effect of joint design and dissimilarity of adherents on damage evolution of adhesive bonding under tensile quasi static loading is analyzed. Bonding was created by toughened epoxy adhesive as one of the most important and widely used structural adhesives in aerospace, automobile and marine industries. Due to structural behaviour complexity of adherents and adhesive, the fracture takes place under mixed mode and the failure mechanism is characterized by the de-bonding area for the proposed joints. The results show that single lap joint could carry up to 30% more tensile load than the double butt lap joint with the same material properties while a combined failure mechanism could be observed and the most dominant ones were yielding of aluminum substrates, adhesive failure at bond-line on aluminum surface and cohesive failure of upper mat layers of composite material.