Towards the 3D in situ characterisation of deformation micro-mechanisms within a compressed bundle of fibres

The present study provides original experimental data concerning the evolution of the microstructure of a bundle of fibres during its deformation. For that purpose, a model saturated fibre bundle was processed and was subjected to a compression loading by using a specially designed micro-compression rheometer which was mounted on a synchrotron X-ray microtomograph. Thus, 3D images of the evolving fibrous microstructure could be obtained. Results first show that the compression induced both the bundle consolidation and liquid phase migration. Secondly, (i) the position, the orientation, the displacement and the deformation of each fibre together with (ii) the position and the evolution of each fibre-fibre contact were followed during the compression. The in situ tracking of these microstructure descriptors allows the consolidation micro-mechanisms to be analysed and provides useful information for theoretical or numerical models used to predict fibre bundle deformation during processing of fibre bundle reinforced polymer composites.