ABSTRACT
A long-standing problem with structural joints made using fibre-polymer composite material is low strength and toughness of the bond-line. Composite joints are susceptible to unstable bond-line cracking under the application of through-thickness tensile load, in-plane peeling stress or impact. Composite joints must be conservatively designed (i.e. over-designed) to take into account the low delamination resistance, strength and damage tolerance of their bond-line. A significant reduction to the weight and cost of joints can be achieved by toughening the bond-line. Various methods are available for strengthening joints including toughened adhesives, thermoplastic film interleaving and through-thickness reinforcement with stitches and z-pinning.
