Experimental and Numerical Study on the Effect of Polyurea Coating Position on the Blast and Impact Resistance of Metallic Plates

Polyurea has emerged as an effective energy-dissipating coating for improving the impact and blast resistance of metallic structures. This study presents an integrated experimental and numerical investigation into the protective performance of polyurea-coated iron and aluminum plates subjected to localized impact and confined internal blast loading. Drop-weight impact tests with a cylindrical impactor were conducted to simulate fragment-like loading, while small-scale internal explosion tests were employed to assess blast-induced deformation under constrained conditions. The effects of coating position (front-face, back-face, and double-sided) and coating thickness on penetration resistance, deformation response, and energy absorption were systematically evaluated. Experimental results indicated that polyurea coatings markedly enhance the impact and blast resistance of metallic plates, with performance strongly dependent on coating configuration. Double-sided coatings provide the highest penetration resistance and energy absorption capacity, followed by front-face coatings, whereas back-face coatings offer comparatively lower but still appreciable improvement. Increasing coating thickness consistently improves resistance to penetration and mitigates localized damage. Under internal blast loading, polyurea-coated specimens exhibit reduced maximum deflection and more uniformly distributed deformation compared with uncoated plates. A coupled Lagrangian–Smoothed Particle Hydrodynamics (SPH) numerical model was developed in LS-DYNA (Livermore Software Technology Corporation) to simulate blast–structure interaction. Numerical predictions show good agreement with experimentally measured deformation profiles and peak deflections obtained from structured-light three-dimensional scanning, confirming the reliability of the proposed model. Scanning electron microscopy observations reveal that, despite localized surface roughening after blast exposure, the internal elastomeric network of polyurea remains largely intact, supporting its sustained ductility and energy-dissipation capability. Overall, the results indicate that optimized polyurea coating configurations, particularly double-sided layouts, provide synergistic confinement and stress-wave attenuation effects, offering a lightweight and effective strategy for enhancing the impact and blast resistance of metallic protective structures.