Additive Manufacturing of Continuous Carbon Fiber Honeycomb Structures with Tunable Poisson's Ratio

This study investigates the mechanical performance of continuous carbon fiber reinforced composite (CCFRC) honeycomb structures with varying Poisson's ratios, fabricated using the fused filament fabrication (FFF) technique. Three honeycomb designs—star shaped (SS), concave hexagonal (CHH), and zero Poisson's ratio (ZPR)—are evaluated through static compression experiments and finite element simulations. The results show that the SS honeycomb with a negative Poisson's ratio exhibits higher yield strength, faster densification, and greater total energy absorption. In contrast, the positive Poisson's ratio (PPR) honeycomb demonstrates larger specific energy absorption, while ZPR structures are more stable in deformation. Notably, for structures with the same negative Poisson's ratio, the SS honeycomb outperforms the CHH in terms of total and mass specific energy absorption, with increases of 98.58% and 101%, respectively. Scanning electron microscopy (SEM) analysis of fiber damage mechanisms during compression highlights the influence of unit cell design and printing path planning on the mechanical properties of CCFRC components. These findings suggest that the mechanical behavior of CCFRC honeycomb structures is highly dependent on design and print path planning, with tensile failure typically leading to brittle fracture.