Experimental investigation into the response of GFRP S-shaped foldcore sandwich panels to impulsive loading

S-shaped foldcore sandwich structures have potential applications as protection structures under impact loading. In this paper, the S-shaped glass fiber composite foldcore sandwich structure was fabricated by hot pressing method and its impact resistance against the aluminum foam projectiles was studied using a one-stage gas gun. The three-dimensional digital image correlation system was used to measure the dynamic deformation of the sandwich panels. During the experiments, the dynamic response of the structure was studied when the projectile impacted the node and base locations of the sandwich structure, where the node location refers to the top platform of the core and the base location refers to the middle position between the nodes. In addition, the influence of the face sheet thickness and core thickness on the impact resistance of the sandwich structure was also investigated. The results show that the sandwich structure is dominated by tensile fracture of the face sheet, crush fracture or extrusion fracture of the core, and debonding failure between the face sheet and the core. The impact resistance of the node location is better than that of the base location for the same configuration. Moreover, the maximum deflection of the rear sheet increases linearly with the increase of the impact loading when impacting the base location. And increasing the face sheet thickness or core thickness can better reduce the structure deflection and improve the impact resistance of the structure.