Ductility of platelet composites inspired by nacre design

Platelet composite design inspired by nacre microstructure has attracted wide interest as a means to improvinge toughness of materials. Presented within this paper are novel approaches in to _engendering simultaneous improvements to the pseudo-ductility and strength improvement simultaneously inof discontinuous fibre reinforced epoxy composites. The approaches were finger-type ply overlapping, discontinuous platelets and z-pin reinforcement of joints. A comparative numerical and experimental study is described in this paper to identify the relationship between ply-overlap length and strain ductility of a platelet composite design with z-pin reinforcement. Larger The results show that a carbon fibre epoxy platelet composite ply overlap length is can _found to retain 45% and 93%, respectively, of the tensile strength and failure strain of the continuous fibre composite counterpart. A relatively small pseudo-ductility strain of 1.07% was observed. Analytical modelling studies towards these were conducted on platelet or discontinuous fibre reinforced epoxy composites withof platelet composites of varying aspect ratios and tiling configurations_. Results suggest that the staggering of the neighbouring ply terminations resulted in an increased tensile strength whereas aligning the ply-termination for each second consecutive ply leads to the increase in strain-to-failure. The incorporation of z-pin reinforcements (stainless steel, copper and carbon fibre/BMI) through-the-thickness of the platelet composite was investigated. The shear-induced work hardening of the metal pins further enhances the pseudo-ductile strain and strength simultaneously; supplementing the shear lag process between the ply overlaps.