Coupled FDM-SPH modeling of CFRP-reinforced concrete damage under combined blast and fragment impact

Reinforced concrete (RC) structures reinforced with carbon fiber-reinforced polymer (CFRP) composites are increasingly popular for blast-resistant designs, yet their failure mechanisms under combined blast and fragment loading remain poorly understood due to challenges in modeling multi-physics phenomena such as shockwave propagation, fluid-structure interaction, and fracture dynamics. This study introduces a novel GPU-accelerated finite difference method -smoothed particle hydrodynamics (FDM-SPH) framework to evaluate damage in CFRP-concrete composite structures subjected to extreme loading. The framework couples SPH for structural damage prediction with FDM for air blast simulation, linked via an immersed boundary method to enable bidirectional fluid-structure coupling. The framework is validated against multiple cases, including high-velocity impact on CFRP laminates and close-range blast loading, demonstrating strong agreement with experimental data. Detailed analysis of CFRP-concrete composites reveals that CFRP significantly mitigates blast-induced deformation, reducing displacement by 38 % compared to single CFRP plate while absorbing 73 % of impact energy through delamination and fiber fracture. The model uniquely captures synergistic damage from combined blast and fragment loads, showing localized penetration and global deformation not observed under isolated loading. These findings underscore CFRP’s efficacy in enhancing blast resilience and provide a validated computational tool for optimizing composite structures in defense and critical infrastructure applications.