Influence of projectile characteristics on penetration resistance of coral aggregate seawater concrete: 3D meso-scale simulations

Coral Aggregate Seawater Concrete (CASC) is an environmentally sustainable material widely used in infrastructure projects in the South China Sea. Despite its increasing application, the dynamic mechanical behavior of CASC under projectile penetration remains poorly understood. A 3D mesoscopic numerical model was used to evaluate key parameters—including projectile velocity, caliber-radius-head (CRH), length-to-diameter ratio (L/d), and projectile inclination—on the penetration depth and ballistic deflection of CASC. Results show that the penetration depth increased with higher projectile velocity, primarily due to increased kinetic energy. Notably, CASC exhibited lower deflection angles compared to ordinary concrete, attributed to the weaker coral aggregates that altered the projectile’s internal trajectory. The CRH was found to inversely affect deflection angles, with sharper projectiles causing lower deflection, and this effect was more pronounced in CASC. Additionally, an increase in the L/d ratio resulted in deeper penetration but lower deflection angles. The projectile inclination significantly influenced both horizontal displacement and penetration depth, with higher angles leading to greater horizontal displacement and reduced vertical depth. These findings provide new insights into the ballistic performance of CASC, suggesting potential applications for enhancing the protection of concrete structures against projectile impacts, particularly in coastal and island environments.