Anisotropic mechanical behavior and failure of foldcore structures of fibre-reinforced composites under impact loading

The foldcore sandwich structure presents a novel approach to impact resistance, making it a compelling subject for research into its mechanical and damage behaviors. This work investigates the damage fracture state and its anisotropic damage behaviour of foldcores subjected to impacts by both experimental and simulation methods. To explore the damage mechanisms of foldcore structures and assess how different foldcore types influence their fracture behaviour, we employed the hot-press method to fabricate V-shaped and S-shaped foldcore structures. Subsequently, impact tests were conducted on these structures to uncover their underlying mechanisms, and Hashin's failure criterion was utilized in the in-face folding direction and out-face folding direction to simulate the damage process and investigate its anisotropy. This study revealed that foldcore structures exhibit anisotropic damage and fracture under impact loading. Damage is predominantly observed along the in-plane folding direction of the foldcore structure, with the damage primarily manifesting as tensile damage to the fibers. The damage incurred by foldcore structures mainly affects the bending region of the structure, where the V-shaped and S-shaped foldcore structures exhibit different damage geometries. © 2024 Elsevier Ltd.