Thickness configuration optimization of B4C/UHMWPE composite armor under varying impact velocities and areal densities: Numerical and experimental study

Thickness configuration optimization is critical to enhancing the anti-penetration performance of ceramic composite armor while maintaining lightweight requirements. This study utilizes the finite element method (FEM) to simulate the ballistic response of B ₄ C/UHMWPE composite targets against 7.62 mm steel-core projectiles, and systematically investigates the influence of ceramic-to-backing thickness ratio ( R _th : 0.4-2.0) on the anti-penetration performance under varying areal density ( AD : 25.0–30.0 kg/m²) and impact velocity ( V ₀ : 344.0-550.0 m/s) conditions. Ballistic testing validates the accuracy of FEM simulation results. The results reveal that the ballistic limit velocity ( V _bl ) initially increases and then decreases as R _th increases from 0.4 to 2.0, peaking at R _th = 1.4–1.6 across all AD cases. Notably, this optimal R _th range remains consistent across AD variations, with both projectile mass loss ratio ( R ^II _m,l ) and kinetic energy loss ratio ( R ^II _ke,l ) during the first two penetration stages peaking within this range, demonstrating robust design applicability. Furthermore, when V ₀ exceeds V _bl , both V ₀ and AD significantly shift the optimal R _th to minimize projectile residual velocity ( V _re ). Under fixed AD , higher V ₀ reduces the optimal R _th due to shortened projectile-armor interaction time, necessitating thicker UHMWPE laminate to prevent premature ceramic fracture failure and enhance the backing-plate energy dissipation. Conversely, under constant V₀ , higher AD elevates the optimal R _th , where AD and V₀ show opposite effects on the variation of optimal R _th , and the optimal R _th converges to 1.4–1.6 as the highest V _bl corresponding to given AD approaches V ₀ . This study establishes a quantitative framework for V ₀ - AD - R _th coupling effects, providing actionable guidelines for designing lightweight composite armor against diverse ballistic threats.