Study on Dynamic Evolution of Anti-Penetration Performance of Polyurea Reinforced Concrete Target Based on FE-SPH Coupling Method

Addressing the issues of brittle spalling and debris scattering commonly observed in Normal Concrete (NC) under high-velocity impact loading, this study investigates the resistance of polyurea-reinforced concrete targets against high-velocity bullet penetration. High-velocity projectile penetration tests were conducted at approximately 510 m/s to comparatively analyze the failure modes of plain concrete targets and targets reinforced with polyurea coatings of varying thicknesses. Furthermore, a three-dimensional numerical model based on the coupled Finite Element-Smoothed Particle Hydrodynamics (FE-SPH) algorithm was constructed to overcome the numerical instabilities inherent in traditional finite element methods when handling large material deformations and debris flows. The experimental results indicate that while the polyurea coating has a limited direct effect on reducing the depth of penetration (DOP)—showing marginal reductions of 1.8% and 2.3% for 2 mm and 5 mm coatings, respectively—it demonstrates a significant physical confinement effect. Notably, the 5 mm polyurea coating effectively suppresses brittle spalling on the impact face, reducing the crater diameter by 15.5% compared to the plain concrete target and restricting the propagation of radial cracks. Energy analysis and interface pressure monitoring reveal that the polyurea coating employs a “peak-shaving and valley-filling” mechanism driven by mechanical impedance mismatch, transforming transient impacts into steady-state compression with lower energy density. Consequently, this significantly enhances the overall impact toughness and secondary protection capability of the structure. These findings provide critical references for the refined reinforcement design of existing defensive structures.