Tailorable through-thickness fibre reinforcement in CFRP laminates with AFP via Repeated Segment Stacking

Composite structures are vulnerable to delamination. With the increased usage of Automated Fibre Placement (AFP) it is important to develop compatible delamination mitigation strategies. In this work we highlight the strategy of segmenting plies and stacking segment-by-segment via AFP, rather than ply-by-ply, to provide through-thickness fibre interlocks to resist delamination. We develop a novel approach, ‘Repeated Segment Stacking (RSS)’, to create significant and tailorable through-thickness fibre reinforcements throughout the thickness. We demonstrate successful AFP prototyping, including the ability to control the fibre undulation geometry. Our results show that low amplitude designs provide reinforcement across all horizontal planes whilst increased amplitude designs mimic the impact resistant Herringbone structure of the Mantis shrimp’s dactyl club. Experimental testing to HVI, LVI, and CAI reveals reduced delamination footprint and containment at undulation boundaries. This first investigation demonstrates that the RSS concept enables composite plates with tailorable through-thickness fibre reinforcement to be manufactured with AFP, and that such designs provide a promising development route for AFP-manufactured delamination resistant CFRP structures. • It is important to mitigate against delamination failure in composite structures. • Through-thickness reinforcement is known to provide resistance to delamination. • Repeated Segment Stacking — repeated stacking of segments to form fibre undulations. • Mesostructures with significant fibre undulations are achieved with AFP manufacture. • Results demonstrate increased delamination resistance of the RSS concept.