Exploiting the optical reflectance behaviour of carbon fibre composites for low-cost inspection and orientations analysis

This work focusses on understanding and exploiting the optical reflectance behaviour of carbon fibre reinforced polymer composites for the non-destructive determination of fibre orientation and surface defects. By taking a series of images under different lighting conditions, fibre reflections have been isolated and MATLAB image analysis has been used to calculate the fibre orientations across the surface of the composite. An average peak method has been developed and validated against manual orientation measurements for two different applications: a machined scarf repair surface and a discontinuous fibre composite. The same experimental method and analysis code showed good results for both cases without modification, when at least 16 images with different directional lighting conditions are used. Hence, this low-cost approach can be applied to a diverse range of quality assurance and research applications where fibre orientations or other surface details need to be characterised.