3D-Quantification of the distribution of continuous fibres in unidirectionally reinforced composites

Synchrotron microtomography is carried out for continuous C-fibre reinforced aluminium and a continuous C-reinforced polymer. The local volume fraction as well as the orientation distribution of the reinforcement are analysed three dimensionally for both composites using self-developed calculation methods. Representative elements for the analysis of the local volume fraction are determined by using two-point probability functions. The results show that regions with smaller volume fractions tend to form channels along the fibre bundles for both composites. Channels of high volume fractions, representing touching fibres (local volume fraction >55 vol%), are identified for the polymer matrix composite. The regions with high volume fraction >50 vol% tend to form clusters in the case of the metal matrix composite. The orientation of the reinforcement is followed throughout the volume of both composites. The results show preferential orientations within each bundle of the fibre reinforced metal. The orientation of the reinforcement is more homogeneous in the fibre reinforced polymer and the largest misorientations are found within the channels separating fibre bundles. The characterisation methods developed in this work can be used to evaluate quality criteria adopted in the stage of development of the composites.