Curved grid‐scored foam core sandwich composites under low‐velocity impact loads: Effects of curvature, stacking sequence, and core finishing

Abstract The objective of this paper is to experimentally investigate how material and geometric parameters, including face sheet layup, curvature, and core finishing, affect the contact force‐displacement behavior, absorbed energy, and damage modes of curved sandwich composites with grid‐scored foam under low‐velocity impact loads. An instrumented drop‐weight testing machine with a hemispherical impactor was used to perform low‐velocity impact tests at different energy levels. Angled‐ply stacking had the maximum contact force and impact resistance for low curvature radii. In the event of penetration, the impact energy absorption of all curved sandwich panels increased as the curvature increased. The core finishing influenced the contact forces of the curved and flat sandwich panels but not the penetration energy. The curvature and face sheet layups affected the delamination size and pattern. Angle‐ply and cross‐ply face sheets with the smallest and maximum radius of curvature, respectively, decreased penetration depth. The resin‐filled channels reduced foam cell impact damage and face‐core debonding. LVI penetration resistance was found to be highest for angle‐ply stacking and knife‐cut foam at small curvature radii. The proposed research will also provide naval designers with valuable insight into the impact response of sandwich structures used in curved parts of the hull and deck. Highlights The effect of curvature on the LVI responses varied due to face sheet layups. Core finishing affected contact forces, but not the absorbed energy. Curvature and face sheet layups affected the damage modes. Resin‐filled channels limited damage area and acted as stoppers for debonding.