Finite element analysis of DOE-optimized shear thickening fluid–impregnated glass fabric for ballistic protection

The demand for lightweight, high-performance ballistic protection has driven increasing interest in shear-thickening fluid (STF)-reinforced composites. This study presents a numerical investigation of plain-woven E-glass fabric composites impregnated with a hybrid nanoparticle STF, optimized using a design of experiments (DOE) approach. The STF formulation consists of 5 wt.% halloysite nanotubes (HNTs) and 30 wt.% SiO₂. Ballistic performance was evaluated using a 9 mm × 19 mm full metal jacket (FMJ) steel projectile at impact velocities of 200, 220, and 250 m/s through finite element simulations in LS-DYNA. The results indicate that STF-impregnated composites exhibit significant improvement in energy absorption under moderate impact velocities (200–220 m/s), achieving efficiencies of approximately 64%–84%, depending on the number of plies. This enhancement is attributed to the activation of the shear-thickening mechanism, which increases inter-yarn friction, promotes load transfer, and improves stress redistribution within the fabric structure. At the higher impact velocity of 250 m/s, the energy absorption decreases to approximately 15%–36%, indicating partial or complete penetration and reduced effectiveness of the STF under extreme loading conditions. These findings confirm that the ballistic performance of STF-based composites is strongly velocity-dependent, with optimal efficiency occurring within the moderate velocity regime. Comparative analysis shows that STF impregnation enhances ballistic resistance by approximately 50% under moderate conditions. Notably, STF-treated laminates with 8–13 plies achieve comparable performance to 20–30 ply neat composites, demonstrating substantial weight reduction without sacrificing protection. These results provide a systematic framework for designing advanced, lightweight protective materials for defense, aerospace, and automotive applications.