A novel hybridised composite sandwich core with Glass, Kevlar and Zylon fibres - Investigation under low-velocity impact

A novel fibre composite sandwich core has been introduced in this study. Trapezoidal corrugated core glass-fibre sandwich structures were hybridised using Kevlar and Zylon fibres to improve the dynamic impact performance. The composite cores were fabricated with four layers of glass fibre and one of the layers was replaced either by Kevlar or Zylon fibre to create hybrid composite core (Glass-to-Kevlar or Glass-to-Zylon ratio 75:25). The impact behaviour, damage mode, specific absorbed energy, and residual strength after the impact of the composite sandwiches were investigated using a low-velocity impact test with 30 J, 40 J and 50 J kinetic energy level. The experimental results revealed that the hybridised sandwiches with high-performance fibre are performing extremely well when subjected to impact energy above the threshold limit. The observations during the experimental work and numerical simulation have confirmed that Glass-Kevlar and Glass-Zylon hybridisation can eliminate severe core rupture by minimising stress concentration and provide high specific energy without increasing structural weight. Moreover, the loss of strength and stiffness of trapezoidal corrugated core sandwich structures after an impact event can be minimised up to 56% and 69%, respectively using Glass-Zylon hybridisation technique. Furthermore, an empirical relationship for predicting the residual strength of the composite core sandwich is proposed.