Examination of drape-induced defects using computer X-ray tomography

X-ray computer tomography has been trialled as a non-destructive examination technique to elucidate defects in dry, woven carbon fibre preforms. Such defects are typically introduced as a result of mapping the cloth to complex tooling geometry; a process often referred to as drape. A conceptual tool was designed and built to create a draped preform with a significant number of defects in localised regions. Cloth deformation was confirmed using kinematic drape modelling. Preform scans highlighted the presence of significant in-plane waviness and ply wrinkles. This was then furthered through scanning of a trial composite propeller blade preform, from which a 180mm long ply wrinkle was discovered. Whilst the quality of defect imagery from X-ray computer tomography is excellent, the introduction of this process at the latter stages of part manufacture is limited by a number of factors. One such factor is the inverse relationship between sample size and final resolution of the scan data. The cost associated with the process also presents a barrier to its widespread industrial usage.