Ballistic performance and deflection mechanisms of a nacre-inspired staggered structure against ogive-nosed projectiles

This study proposes a bio-inspired protective structure composed of staggered hexagonal SiC ceramic tiles and sand layers, aimed at deflecting projectiles and reducing their penetration depth into concrete substrates. Ballistic impact tests were conducted using ogive-nosed steel projectiles at velocities of 500–600 m/s. A coupled discrete element finite element (DEM-FEM) model was developed and validated against experimental data. Results demonstrate that the nacre-inspired staggered design effectively induces a pronounced projectile deflection of about 20° during impact. The protective effect of the staggered structure is realised through two synergistic mechanisms. First, central impacts on ceramic tiles induce tip blunting and velocity reduction via interface defeat. Second, impacts near tile edges generate asymmetric loading, leading to trajectory steering through yaw amplification. The staggered arrangement ensures sequential off-centre impacts, generating lateral forces and moments that initiate projectile yaw, while the intervening sand layers sustain these perturbations through weak confinement. The impact location was found to play an important role in governing the ballistic response, with either blunting or deflection. A key advantage of the proposed staggered design is its ability to amplify the projectile’s deflection angle within the concrete by a factor of 7.2, owing to the significant angular velocity and a finite attack angle imparted upon exit from the bio-inspired protective structure. This proof-of-concept study elucidates the efficacy of the bio-inspired staggered protective systems in ballistic resistance and deflection, providing a design strategy for the retrofitting protection against ogive-nosed penetrators.