Impact response of a new kevlar/flax/epoxy hybrid composite using infrared thermography and high-speed imaging

Abstract

The impact behaviour of woven kevlar fibre/flax fibre/epoxy (WK-F-E) hybrid composites that is made of 12 layers of flax fibres (F) sandwitched in 4 layers of plain-woven Kevlar 49 fibres (WK) is investigated via the use of two configurations: woven Kevlar/unidirectional flax/epoxy [0-902K/06F]S (WK-UDF-E) and woven Kevlar/cross-ply flax/epoxy [0-902K/(0/90)3F]S (WK-CPF-E) laminates. The specimens were subjected to low velocity impact using a pendulum impactor. IR thermography images of the damaged area, in addition to high-speed imaging, and optical microscopy were used to investigate the impact performance in terms of the energy absorbed during impact, damage size, and indentation depth. The results showed that both the WK-UDF-E and WK-CPF-E composites exhibited similar characteristics under low velocity impact with an impact energy penetration threshold of 27 J and impact toughness of 187 kJ/m2, which is slightly better than those of aluminum alloys and carbon/epoxy composites. An approximate tripling of the penetration energy threshold of UD pure flax composites was observed with hybridization.