Experimental study of adhesively bonded natural fibre composite - steel hybrid laminates

Natural fibre composites (NFC), such as flax fibre reinforced plastics are green material with good specific properties. Significant research is currently in progress to improve the mechanical properties and durability of these composites and to make them competitive to traditional synthetic composites. A multi-material design approach is proposed in this study to develop a novel hybrid structure with a thin metal layer adhesively bonded to NFC. Two adhesives; a commercial epoxy adhesive and natural rubber were used for the adhesion between a stainless steel layer and flax composite with thermoset and thermoplastic matrix. The performance of the hybrid joint was investigated using a single lap joint (SLJ) test supported by full-field displacement measurement methods. The manufacturing of the composite specimen and the bonding of the NFC - metal joint with rubber adhesive was demonstrated. The force displacement curves from the SLJ test showed that the bonded joint with epoxy adhesive was stronger in comparison to the bonding with natural rubber. It is supported by the adherend failure observed in the joint with epoxy adhesive, while the rubber joint showed adhesive failure. The key outcome of the research is that the viability of adhesively bonded NFC - metal hybrid is established.