Disrupting Fracture Toughness Of Adhesively Bonded Joints By Tailoring Composite Substrates

Abstract

This work aims to improve the damage tolerance of secondary adhesively bonded joints under quasistatic mode I loading conditions by architecting the carbon fibre-reinforced polymer substrates’ stacking sequences [1]. Double Cantilever Beam tests show that architecting the stacking sequence of the laminates composite substrates in combination with the adhesive layer’s fracture toughness affects the crack onset and triggers different crack paths throughout the joints’ thickness. In specimens bonded with a low-toughness bi-component adhesive, the tailored design, including a co-cured toughening layer, could increase the effective fracture toughness of the composite bonded joints up to 200%. From this study, it was possible to recognise the complexity and benefits of moving from the traditional cohesive failure to outbreaking multiple crack path propagation.