New metal-epoxy-matrix carbon-fibre hybrids to tackle stress concentration

The paper explores the feasibility of improving the performance of composite structures with stress concentrators by local infusion of metals. The resulting material architecture presents Multi-Matrix Continuously-Reinforced Composites (MMCRC) – with shared domains of both the thermoset polymer and metal matrices with fibre-bridged interfaces between the domains. The study explores the manufacturing routes to creating such composites and assesses the resulting performance using the open-hole tensile test. It has been demonstrated that the presence of a rigid multi-matrix patch around the open hole, exhibiting minimal thickness variation, leads to a 15.0% improvement in failure load and a 16.6% improvement in failure strain for quasi-isotropic carbon fibre composite laminates. The strain history analysis of the MMCRC samples indicates the occurrence of plastic yielding within the metal matrix and strain redistribution mechanisms, leading to load sharing over the hybrid matrix area.