Measurement of fibre waviness in industrial composite components

Fibre orientation is measured from polished sections of the unidirectional plies of two industrial CFRP components made by resin transfer moulding (RTM) or prepreg/vacuum consolidation. The image analysis technique described by Creighton et al. [Composites: Part A 2001; 32: 221–229] is used to determine the fibre orientation over typically 5 × 5 mm sections. The standard deviation in fibre orientation angle is in the range 0.6–1.8°, being smallest for in-plane waviness of the prepreg component. The length and width of the waviness region along and transverse to the fibres is characterised using autocorrelation. The length is in the range 1.1–4.4 mm, being significantly greater in the prepreg than in the RTM component. The width is in the range 0.37–1.30 mm and is broadly similar across the sample types. It is demonstrated that the image analysis method can also be applied to X-ray images, giving good agreement with results from the polished prepreg samples.