Impact Damage Mechanisms in Hybrid Chopped Aramid–Basalt UHMWPE Composites Under Gas–Gun Loading

ABSTRACT Hybrid fiber reinforcement provides an effective pathway for tailoring the ballistic response of ultrahigh molecular weight polyethylene (UHMWPE) composites; however, the impact behavior of chopped‐fiber hybrid architectures remains largely unexplored. In this study, UHMWPE composites reinforced with systematically varied combinations of chopped aramid and basalt fibers were fabricated with a fixed matrix content of 80 vol% and evaluated under high‐velocity gas–gun impact conditions. Rockwell hardness increased progressively with basalt fiber content, with the basalt‐rich composite (UBA3) exhibiting the highest indentation resistance. Ballistic testing revealed a strong compositional dependence of impact response, with the aramid‐rich composite (UBA1) exhibiting the lowest residual velocity (134.6 m s −1 ), highest energy dissipation (175.28 J), and energy equivalent velocity parameter ( V eq ≈170.21 m s −1 ), despite lower hardness. In contrast, basalt‐rich composites displayed higher residual velocities and more localized penetration. Scanning electron microscopy revealed a transition in dominant damage mechanisms from tensile‐dominated fiber stretching and pull‐out in aramid‐rich systems to matrix‐dominated crushing and fiber fracture in basalt‐rich formulations. Differential scanning calorimetry further indicated composition‐dependent changes in crystallization behavior and crystalline fraction of the UHMWPE matrix, with crystallinity increasing from ~17.4% to 27.25% with increasing basalt content. Collectively, these results demonstrate that hybrid fiber composition, rather than total reinforcement content, governs the ballistic efficiency and damage evolution of chopped‐fiber UHMWPE composites, establishing their potential as scalable, quasi‐isotropic alternatives to fabric‐dominated ballistic systems.