Characterisation of 3D woven composite internal architecture and effect of compaction

Abstract

Yarn waviness and resin rich regions play a major role in 3D woven composite mechanical properties and failure. A detailed study of two angle-interlock 3D woven carbon fabrics has been carried out to characterise these architectural features and how they change under increasing levels of compaction. Computerised tomography (CT) xray scanning was used to capture the internal architecture of the fabrics. The study focussed on the out-of-plane crimp of the yarns and the size and shape of resin rich regions in consolidated panels. Results showed areas of high local crimp at weft/weaver interlace points. This was exacerbated at low levels of compaction but was eventually lowered under higher compaction levels. The appearance of resin channels was found to be heavily dependent on weave style, with large resin pockets appearing in weaver yarn planes which decreased significantly in size under compaction with distinctive changes in profile.

Finite element modelling of tow geometry in 3D woven fabrics

“…The study focussed on a statistical analysis of out of plane crimp of the yarns as well as the size and shape of inter-yarn resin channels. The results taken from the finite element model were verified by comparison with experimental results from a previous study [21]. The mesh was designed to be a "loose-weave" which would be tensioned to achieve a final thickness and architecture to match that of the uncompressed weave.…”

Numerical modelling of 3D woven preform deformations

“…A dry fabric specimen was used since this allowed the fabric to be subjected to an in-situ compaction test, eliminating any effects due to variation between different specimens infused at different thicknesses (as per [9]). This also meant that it was not necessary to infuse multiple samples at the various levels of compaction.…”

“…Mahadik et al demonstrated the importance of this effect in an angle interlock 3D woven fabric where the amount of yarn waviness and size and shape of resin pockets varied significantly with the level of compaction [9].…”

Stochastic Virtual Tests for High-Temperature Ceramic Matrix Composites

“…Investigators have measured characteristics of textile geometry and tow deformation (8,13,55), as well as porosity (56) and its changes during processing steps (56,57). The same technique is now yielding 3D images of damage captured in situ under load at very high temperatures, which is key to informing simulations of damage evolution (58).…”