Dynamic response to high‐velocity impact on 3D fiber metal laminates (3D FMLs) incorporating a nano‐reinforced syntactic foam core

Abstract This study presents an experimental investigation into the high‐velocity impact resistance of three‐dimensional fiber metal laminates (3D FMLs) incorporating a nano‐reinforced syntactic foam core. Reinforced and unreinforced 3D FMLs were fabricated with varying nanoclay concentrations (0, 3, 5, and 7 wt.%) and subjected to high‐velocity impact testing. The impact experiments were conducted using a light gas gun and a 9 mm steel projectile, achieving an impact velocity of 235 m/s to determine the ballistic limits. The dynamic response and failure mechanisms of the laminates were characterized through field emission scanning electron microscopy (FESEM) to evaluate the influence of nanoparticle reinforcement on impact resistance. The results indicated that the incorporation of 5 wt.% nanoclay resulted in an 18.84% reduction in residual velocity and a 14.97% increase in energy absorption relative to the unreinforced 3D FMLs. Morphological analysis via FESEM and macroscopic inspection demonstrated enhanced interfacial adhesion between the resin and fiber, mitigated matrix microcracking, and reduced delamination, attributed to the nanoclay reinforcement. However, the presence of nanoclay diminished the adhesion strength at the aluminum‐composite interface, leading to exacerbated plastic deformation of the aluminum layers. Microstructural examination further revealed that nanoclay incorporation facilitated fiber fibrillation, thereby improving the energy dissipation capacity of the laminate under high‐velocity impact loading. Highlights Nanoclay‐reinforced 3D fiber metal laminates (FMLs) improve impact resistance, with 5 wt.% nanoclay yielding optimal ballistic performance and energy absorption under high‐velocity impact conditions. High‐velocity impact tests using a light gas gun and 9 mm steel projectile at 235 m/s determined the ballistic resistance of FMLs. FESEM analysis revealed enhanced interfacial adhesion, reduced matrix cracking, and improved delamination resistance, leading to superior energy dissipation in reinforced laminates. The 5 wt.% nanoclay FMLs showed an 18.84% reduction in residual velocity and a 14.97% increase in energy absorption compared to unreinforced samples. Excessive nanoclay (7 wt.%) led to nanoparticle agglomeration, increasing stress concentrations, crack density, and reducing overall mechanical performance.