Dynamic response and failure mechanism of S-shaped CFRP foldcore sandwich structure under low-velocity impact

To study the impact resistance of the S-shaped carbon-fiber foldcore sandwich structure, the S-shaped foldcore was prepared by the hot press molding process, and then the S-shaped carbon-fiber foldcore sandwich structure was designed by face-to-core bonding and curing through a secondary bonding process. Two hemispherical impactors with different diameters were used to preload different energies to impact the node position and base position of the sandwich panel, respectively, revealing the failure mechanism, response characteristics of the sandwich panel, and the influence of various variables on the impact resistance of the structure. The research shows that the panel of S-shaped foldcore sandwich structure has tensile fracture failure. The core is affected by the structural characteristics and load-bearing forms, and there are mainly two failure modes of brittle crushing fracture and tensile fracture. The load-displacement curve shows that the relative size of the impactor and the unit cell of the core has a significant influence on the impact damage behavior. The sandwich panel has better impact resistance for the impactor with diameter greater than the cell span, and the difference between different impact positions is reduced. In application, the span of the core cell can be reduced to further improve the protective effect of the structure. The sandwich structure studied in this paper is lightweight and has good impact resistance, which can be used in the field of lightweight protection in the future.