Characterisation and Control of Fibre Alignment during Prepreg Manufacture

A procedure is presented for characterisation of fibre misalignment in composites. It is based on analysis of low magnification images in which the local fibre direction can be inferred from the orientation of elongated features in the image. Specimen preparation and image analysis procedures are presented and their usage is illustrated by application to a carbon fibre composite. Factors affecting the choice of certain image analysis parameters are briefly explored. It is shown that the proposed method is robust, sensitive and experimentally convenient. It is particularly well-suited to the characterisation of specimens exhibiting significant variations in fibre alignment direction over large distances, ie pronounced fibre waviness, and the potential utility of such measurements for the prediction of compressive strength is highlighted.