Concurrent use of Z-pins for crack arrest and structural health monitoring in adhesive-bonded composite lap joints

Abstract Adhesive-bonded joints in carbon fibre-reinforced polymer laminates are cost effective, but their fatigue cracking potential currently limits aerospace certification. We investigated the concurrent use of Z-pins for crack arrest (including an analysis of underlying mechanisms) and structural health monitoring (SHM) in adhesive-bonded composite lap joints. The use of Z-pins resulted in a crack arrest capacity 33% higher than the joint's static limit load and produced a residual strength that far exceeded current ultimate loads (250 versus 150% of the limit load). The electrical resistance in the Z-pins was consistent with observed trends in crack growth, suggesting its viability for SHM.