Finding fibres and their contacts within 3D images of disordered fibrous media

Modelling physical and mechanical properties of fibrous materials requires a relevant description of their microstructures, e.g. the descriptors of fibres and fibre-fibre contacts. In this work, a method is proposed to identify fibres with complex cross sections and their contacts from 3D images of disordered fibrous media, obtained from X-ray microtomography. The image analysis procedure first consists in obtaining a map of the local fibre orientation. Fibres are then detected by deleting regions of high local orientation gradients. Therewith, dilatation operations using slender orientated structuring elements are performed to retrieve deleted fibre parts. The procedure thus provides 3D images with labelled fibres and fibre-fibre contacts. Its relevance is assessed by analysing the microstructures of three typical fibrous media used in short fibre reinforced polymer composites or as paper materials: mats of (i) mono-disperse copper fibres with circular cross sections, (ii) glass fibres bundles, (iii) wood fibres.