Cross-helicoidal approach to the design of damage-resistant composites

The design of impact-resistant composite laminates could be inspired by a biologically helicoidal architecture where a series of thin unidirectional fibre laminas are stacked one by one, with the orientation of each fibre layer rotating sequentially by a near-constant angle. The results of low-velocity/face-on impact show that the excessive diffusion of damage inside the helicoidal configurations poses a potential threat to the structural integrity of size-limited laminates, even though the fibre failure is suppressed (which tends to occur in the Cross-Ply controls, resulting in lower contact force). Here, we propose a cross-helicoidal design strategy for the fabrication of high-performance helicoidal composites with variable rotation angles. By adjusting the relative position of the ori-ented fibre sheets, this cross-helicoidal architecture changes the out-of-plane stiffness of the original helicoidal configuration, resulting in a rather different impact response. Both experimental data and numerical simulations confirm that the introduction of this cross-helicoidal design significantly improved the impact resistance of laminates, with larger impact peak forces and much smaller projected damage area.