Tow Visualisation in Woven Composites using X-Ray Computed Tomography

This paper discusses a technique to visualize the tow architecture in a non-destructive manner, with the final intention of allowing tow visualisations in three dimensional woven carbon-fibre preforms. The tow architecture of plain woven fabric carbon composites, as well as glass composites, has been visualised with the use of MicroCT. Two methods of image acquisition have been discussed. The first uses traditional X-ray imaging. The second uses a newer method known as X-ray phase contrast imaging, combined with the traditional method. Because of the similar densities of carbon and polyester resin it is somewhat difficult to discriminate between tow and resin interfaces when viewed using X-rays, leading to the need for contrast enhancement. This problem is somewhat reduced when using glass in the place of carbon. Attempts have been made to improve contrast, which have included treatments of the fabric and/or resin prior to consolidation. The outcomes from various specimen production are presented and discussed with particular emphasis on the generation of three dimensional images of the tow architecture.