Tracking the evolution of a defect, characteristic of AFP layup, during cure with in-process micro-CT scanning

An increased understanding of how features such as voids change during the cure process can inform design and manufacturing process choices. This paper presents the detailed evolution of a prepreg defect throughout the cure process, using a novel method of In-Process Micro-CT. A Nikon XTH-320 industrial CT scanner was equipped to allow curing of an uncured prepreg sample under vacuum. Short scans of approximately 7 minutes were performed repeatedly during cure. Here we discuss the evolution of a cylindrical sample of a carbon fibre prepreg containing a 2 ply thick 2mm gap along the fibre direction across the centre, typical of defects found in AFP processes. The evolution of the gap is compared to the theoretical resin behaviour. In-process micro-CT has the potential to provide far more detailed information on the behaviour of composites during cure than has been available prior to today. This work provides both proof of the principle, as an experimental method, and shows detailed results measuring the evolution of a gap during the cure of carbon fibre prepreg materials.