Automated tape lay-up (ATL) combined with Hot Drape Forming (HDF) offer cost competitive manufacturing for large composite components. However, not carefully performed HDF of composite laminates could end up with out-of-plane fibre wrinkling. Previous studies with this technique has shown that the stacking sequence have a significant influence on wrinkle development during 3D-forming. One possible explanation to this might be the relatively high interply friction for the combination of [0] and [ 45] layers. Prepregs containing thermoplastic toughener particles show a higher level of interply friction compared to prepregs which do not contains such particles. It is therefore likely that interfacial particles in general will increase the interply friction. Such particles could be thermoplastic toughener or aligned multiwall carbon nanotubes (MWCNT). The aim of this study is to show how locally arranged MWCNTs in prepreg interlayers affect the global forming behaviour. An initial study of intraply shear and interply friction is performed with purpose to investigate how pregpreg with MWCNT interlayers on general influence the forming. Further an experimental forming study is performed with aligned MWCNT in the [-45] / [0] interlayers of a quasi-isotropic prepreg stacking sequence. A numerical study is also performed simulating the forming of the experimental spar geometry. The results show that the intraply shear resistance of the MWCNT containing material is 100% higher than for the reference. Further the interply friction is 3 to 4 times higher for the MWCNT containing material compared to the reference. The experimental spar study shows increased out-of-plane wrinkling in the joggled spar flange when using MWCNT in the [-45]/[0] interlayers. The numerical study strengthen the experimental results by showing increased compression across the fibre direction in the [0] layer when adding contact surfaces in the [-45]/[ 0] interlayers.
QC 20211021