Projectile penetration into geopolymer-based ultra-high performance concrete: Constitutive model calibration and experimental validation

Geopolymer-based ultra-high performance concrete is a novel engineering protection material that combines high performance with low cost. To accurately characterize and reliably simulate the impact penetration and failure process of projectiles into G-UHPC targets, this study conducted a series of experiments and ultimately calibrated a set of parameters for the Kong-Fang constitutive model suitable for simulating projectile penetration into G-UHPC. Regarding fundamental mechanical properties, a series of static and dynamic experiments were performed, including uniaxial compression, tension, true triaxial compression, hydrostatic compression, Split Hopkinson Pressure Bar (SHPB) compression, and splitting tests. Based on the obtained experimental data, parameters for the Kong-Fang model, such as the strength surface, strain rate effect, and equation of state (EOS), were calibrated. For validation, projectile penetration experiments involving 50-mm-diameter projectiles at low velocities into G-UHPC targets were conducted. The experimental results were compared with numerical simulations to verify the reliability of the calibrated model parameters. It is indicated that the penetration depths and crater diameters in the targets simulated with the calibrated Kong-Fang model agree well with the experimental measurements. The calibrated parameters and the established FE model can reliably predict the damage of G-UHPC targets subjected to projectile penetration.