Pseudo-ductility and reduced notch sensitivity in multi-directional all-carbon/epoxy thin-ply hybrid composites

Abstract

Un-notched and notched tensile response and damage accumulation of quasi-isotropic carbon/epoxy hybrid laminates made of ultra-high modulus and intermediate modulus carbon fibre/epoxy thin-ply prepregs were studied. It was confirmed that the ply fragmentation demonstrated previously in unidirectional hybrids as a successful pseudo-ductility mechanism can be transferred to multi-directional laminates. Furthermore, reduced notch sensitivity was demonstrated in quasi-isotropic specimens for both open holes and sharp notches as a result of local ply fragmentation around the notch

Notch insensitive orientation-dispersed pseudo-ductile thin-ply carbon/glass hybrid laminates

“…In all the configurations, free edge delamination, an undesirable damage mode in previously investigated orientation-blocked hybrids [29], was successfully suppressed due to the orientation-dispersed design [30] that produces lower energy release rates at the free-edges of the laminates.…”

“…This study presents a comprehensive set of designed and characterised orientation-dispersed pseudo-ductile thin-ply glass/carbon hybrid composites to overcome some of the disadvantages behaviour. CT-scan observation was necessary to determine the damage scenario, as the hybrids were all carbon and it was not possible to see the damage evolution visually [29]. The investigated hybrids in this paper have the advantage of allowing monitoring of the damage evolution with the naked eye, due to the translucent nature of the glass layers.…”

“…Early work on pseudo-ductile composites [22][23][24][25][26][27][28] reported that by combining different types of thin-ply carbon fibres and standard glass fibres, an optimised gradual failure process can be achieved in tension that can avoid catastrophic failure. In these studies, unidirectional hybrids were used to generate pseudoductile behaviour, with the concept then applied on quasi-isotropic (QI) laminates [29][30][31]. It was found that by changing the relative and absolute thickness of the carbon layer as well as the material properties, three damage mechanisms, i.e.…”

“…Un-notched and notched tensile response and damage accumulation of multi-directional carbon/epoxy hybrid laminates made from ultra-high modulus and high strength have been studied [29]. Locally active fragmentation in the notched QI specimens demonstrated a notchinsensitive behaviour, but a significant free edge delamination occurred due to the choice of the UD hybrid sublaminates that were used as the building blocks of the hybrid laminates.…”

3D printed continuous fibre-reinforced composites: Bio-inspired microstructures for improving the translaminar fracture toughness

“…The reported values for 0° carbon fibre/epoxy plies are in the range of 20-280 kJ/m² [1,[3][4][5][6][7]. This is significantly higher than interlaminar fracture toughness values, which typically range from 0.2 to 3 kJ/m² [7][8][9][10][11]. This is primarily because translaminar fracture is controlled by significant fibre/matrix debonding and pull-out, both of which can absorb large amounts of energy.…”