Modeling projectile penetration into RC structures using truss-enhanced adaptive FEM–MPM

Traditional FEM-based simulations of projectile penetration into reinforced concrete (RC) structures tend to suffer from mass loss and reduced accuracy due to the adoption of element erosion techniques. To address these issues, this study introduces a novel Truss-Enhanced Adaptive FEM–MPM (TEAFEMPM) framework, which seamlessly integrates solid finite elements, truss components, and the Material Point Method (MPM) within a unified computational environment. Concrete is modeled using three-dimensional solid elements, whereas steel reinforcement is represented by one-dimensional truss elements, coupled to the concrete through velocity- and acceleration-based constraints. When subjected to severe deformation, distorted solid elements are adaptively transformed into MPM particles. The remaining solid elements, material particles, and truss components interact synergistically to capture the full dynamic response of RC structures. A modified Karagozian & Case (K&C) material model is employed, incorporating enhanced yield scaling and damage evolution laws to better represent the strain-softening behavior of concrete under external loading. The adaptive transition and coupling strategy are validated through both unconfined uniaxial compression (UUC) and tensile tests. Finally, numerical simulations of projectile perforation in RC panels show excellent agreement with experimental data, confirming the accuracy and efficiency of the proposed TEAFEMPM framework.