Ballistic impact response of Elium® thermoplastic composites reinforced with high-performance fibres in monolithic and hybrid configurations

This study investigates the ballistic impact response of composite armour panels manufactured with infusible Methyl Methacrylate, thermoplastic (Elium®) resin, reinforced with three distinct plain weave fibre systems: carbon, Kevlar, and Ultra-High Molecular Weight Polyethylene (UHMWPE). Both monolithic and hybrid panel configurations were assessed. The primary aim is to evaluate the feasibility of Elium®-based composite armour for ballistic protection and to determine the influence of fibre hybridisation on impact resistance and damage characteristics. Composite panels were manufactured using vacuum-assisted resin transfer moulding, incorporating 16 layers of plain-woven carbon, Kevlar, UHMWPE, and their 8-layered hybrid combinations (carbon/Kevlar, Kevlar/carbon, carbon/UHMWPE, and UHMWPE/carbon). Ballistic testing employed .38 SPL lead round nose projectiles (300 ± 15 m/s) and .357 MAG semi-jacketed soft point flat projectiles (550 ± 15 m/s). Ballistic performance was evaluated by analysing damage patterns, back face deformation, energy absorption, and residual velocity. X-ray imaging provided an internal damage assessment. Kevlar and UHMWPE-based panels successfully stopped the .38 projectile with minimal back face deformation. In contrast, carbon-reinforced panels exhibited significant residual velocities and did not prevent projectile penetration in the monolithic condition. All single-fibre-reinforced panels were perforated by the .357 projectile, though to varying extents. Among the hybrid systems, Kevlar-backed carbon-facing panels demonstrated superior ballistic resistance compared to the carbon-backed Kevlar-facing configuration. The carbon/UHMWPE hybrid exhibited relatively poor performance, as only one .38 projectile was successfully stopped. For the carbon-backed UHMWPE-front hybrid panel, all projectiles perforated the panel. Kevlar and Kevlar-backed hybrid panels achieved the highest energy absorption and lowest residual velocities, indicating Kevlar's superior energy dissipation properties in hybrid armour systems. These results demonstrate the potential of Elium® resin-based composite panels for advanced ballistic protection and highlight the critical role of fibre hybridisation in improving the ballistic performance of composite armour.