On the electrical properties of multi scale reinforced composites for damage accumulation monitoring

The variation of the electrical resistance of Carbon Fibre Reinforced Polymers (CFRPs) when subjected to load provides a direct measure for strain and damage accumulation monitoring. Multi scale reinforcement where carbon nanotubes (CNTs) are employed as reinforcement in the nano scale in conjunction with the primary reinforcement is in the forefront of current research. CNTs in the epoxy matrix provide an electrical network within the insulating matrix which performs as an inherent sensor in the composite structure. The primary reinforcement may also be conductive, as in the case of carbon fibres. Strain is manifested as a reversible change in resistance, whereas every invisible crack due to mechanical loading is manifested as an irreversible increase. The aim of this work is to exploit the electrical properties of both conventional and CNT enhanced carbon fibre reinforced polymers with a view to identify the sensing capabilities in terms of strain variation and global damage, especially in the case of multiscale reinforcement.