Abstract

Extrinsic Fabry Perot Interferometer (EFPI) fibre optic sensors have been utilised to measure the internal matrix strain in a three dimensionally woven carbon fibre reinforced polymer composite. EFPI sensors were embedded at two levels within a four layer 3D woven composite, and comparison surface measurements were provided through resistive strain gauging and biaxial extensometry. A variation in tensile modulus of as much as 24% was found from internal measurement compared with the material surface. Through correlation with micro-graphical analysis, a link between the variations in mechanical performance and localised variations in fibre volume fraction could be established. Furthermore, the impact performance was measured.