Thickness configuration optimization of B4C/UHMWPE composite armor under varying impact velocities and areal densities through numerical and experimental study.

This study aims to optimize the ceramic-to-backing thickness ratio (Rth) of B4C/UHMWPE composite armor to enhance the anti-penetration performance while maintaining lightweight requirements. Its primary innovation lies in systematically quantifying, through combined finite element method (FEM) and ballistic testing, the coupling mechanism of thickness ratio (Rth: 0.4-2.0), areal density (AD: 25.0-30.0 kg/m²), and impact velocity (V0: 400.0-550.0 m/s) governing the anti-penetration performance of composite armor. The results reveal that the ballistic limit velocity (Vbl) initially increases and then decreases as Rth increases from 0.4 to 2.0, peaking at Rth = 1.4-1.6 across all AD cases. Notably, this optimal Rth range remains consistent across AD variations, with both projectile mass loss ratio (RIIm,l) and kinetic energy loss ratio (RIIke,l) during the first two penetration stages peaking within this range, demonstrating robust design applicability. Furthermore, a key finding and significant contribution is the dynamic shift in the optimal Rth for minimizing projectile residual velocity (Vre) when V0 exceeds Vbl: Under fixed AD, higher V0 reduces the optimal Rth 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 Rth, where AD and V₀ show opposite effects on the variation of optimal Rth, and the optimal Rth converges to 1.4-1.6 as the highest Vbl corresponding to given AD approaches V0. Critically, this study establishes a quantitative framework for V0-AD-Rth coupling effects, providing actionable guidelines for designing lightweight composite armor against diverse ballistic threats.