Mechanical and vibration response of insulated hybrid composites

Electrically nonconductive composites are required in various engineering applications ranging from radome, antenna and many more. This research aims at investigating the mechanical properties of electrically non-conductive hybrid composites (thin carbon non-crimp fabric, Kevlar and E-glass fabrics) in combination with thermosetting epoxy resin. The composites comprise of multi-axial textile reinforcement carbon fabrics in the middle section with symmetrical quasi-isotropic layup, sandwiched with Kevlar fibre for improved impact performance and E-glass fibre at the outermost parts for electrical insulation. The fabrics are injected with room-temperature-cure epoxy using economical and energy saving resin transfer moulding manufacturing process. Electrical continuity tests and mechanical properties including vibration damping response, flexure and impact were studied to investigate the performances of the manufactured hybrid composites. Three hybrid laminate configurations were manufactured, and experimental results showed that hybrid composite with more number of Kevlar layers performed better for vibration and flexure testing. For impact performance, results showed that the absorbed impact energy improved with the inclusion of more glass layers, whereas configuration with more Kevlar layers experienced greater peak load to failure. The details of the composites fabrication, manufacturing and experiments conducted and the related findings with underlying reasons for the improvement offered by particular group of laminate configuration are discussed in the article.