Multi-objective assessment of drop-weight impact in 3D-printed fiber-reinforced nylon composites

This study investigates the drop-weight impact behavior of 3D-printed Nylon composites reinforced with continuous carbon, glass, and Kevlar fibers for impact-critical applications such as high-voltage marker balls. Using a Taguchi L27 orthogonal array, key factors, fiber orientation (0°, 45°, 90°), infill pattern (rectilinear, triangular, gyroid), fiber type, and infill percentage (30%, 40%, 50%)—were varied. Peak force, deformation, and energy absorption were measured per ASTM D7136, and optimized using entropy-weighted Multi-Criteria Decision-Making (MCDM) methods (RAWEC, TOPSIS, CoCoSo). The optimal configuration (0°/rectilinear/glass/50%) exhibited 2776.99 N peak force, 11.01 mm deformation, and 22.92 J energy absorption. SEM and EDS analysis of fracture surfaces revealed that glass fiber composites demonstrated ductile damage modes including fiber bridging and matrix flow, whereas carbon fiber composites failed via brittle fiber splitting and interfacial debonding. Post-impact evaluation showed that glass fiber composites retained up to 73% of their tensile strength and 67.9% of compressive strength. Specific Energy Absorption (SEA) analysis highlighted that Kevlar composites in triangle/gyroid infills with 30% density exhibited the highest energy-to-weight efficiency (up to 47.85 J·cm 3 /g). A fiber-type-specific optimization identified the best infill strategy for each reinforcement. The integrated framework presents a validated pathway for lightweight, impact-resistant composite design tailored to structural energy infrastructure.