Numerical Investigation of Fragment Impact and Penetration into Concrete Using the Adaptive SPH Method

Structural damage under blast conditions is significantly influenced by high-velocity primary fragments, which can induce severe local penetration and threaten the safety of protective structures. In this study, the penetration behavior of concrete subjected to primary fragment impact was investigated using the Adaptive Smoothed Particle Hydrodynamics (SPH) method implemented in LS-DYNA. The numerical model was first validated against gas-gun experimental results, demonstrating improved prediction accuracy compared to the conventional Lagrangian approach. In particular, the Adaptive SPH method effectively mitigated premature element erosion, resulting in a residual velocity prediction error of approximately 5.9%. Based on the validated model, a parametric study was conducted to evaluate the effects of fragment mass (3.7–44 g) and impact velocity (750–1000 m/s) on concrete penetration behavior. The results showed that most fragments were capable of perforating a 100 mm thick concrete wall at velocities above 1000 m/s, while partial penetration occurred only under limited conditions. Furthermore, a strong logarithmic relationship between fragment mass and residual velocity was identified, and predictive equations with high reliability (R2 ≥ 0.98) were proposed. These findings demonstrate the applicability of the Adaptive SPH approach for realistic penetration analysis and provide practical insights for the design and safety assessment of protective concrete structures.