Mechanical and energy absorption behaviour of woven carbon fiber reinforced PLA lattice-core structures

In this study, the mechanical and energy-absorption behaviour of Fused Filament Fabrication (FFF) printed PLA lattice structures reinforced with woven carbon fiber fabric were experimentally investigated. Octet and Cross lattice structures were fabricated using PLA + filament, and a total of four layers of 200 g/m 2 plain woven carbon fiber fabric were applied to the top and bottom surfaces of the selected samples (two layers each). The carbon fiber fabrics were applied to the lattice structures using hand laying and hot pressing methods, thus obtaining hybrid lattice core composite structures. The results show that carbon fiber reinforcement significantly improves the load-carrying capacity and energy absorption of the lattice structures. In three-point bending tests, the maximum load capacity increased from 0.3 to 0.9 kN for the Cross lattice structure and from 0.8 to 3.2 kN for the Octet lattice structure. Under low-velocity impact, the reinforced Octet lattice structure reached peak loads of approximately 20 kN and absorbed up to 125 J of energy, exhibiting the highest energy absorption among the tested configurations, although perforation occurred at an impact velocity of 5 m/s. The findings demonstrate that the effectiveness of carbon fiber reinforcement is strongly dependent on lattice structure and relative density. The combined use of lattice design and external carbon fiber reinforcement provides an effective strategy for developing lightweight polymer composite structures with enhanced mechanical performance and energy dissipation capacity.