Mechanical properties and lightweight design of FDM-produced fiber-reinforced composite structures

This study systematically investigated the synergistic effects of nozzle diameter and infill geometry on the mechanical properties and lightweight potential of short carbon fiber-reinforced ABS composites fabricated by fused deposition modeling (FDM). Sandwich specimens were produced with three nozzle diameters (0.4, 0.6, and 0.8 mm) and four infill patterns: Gyroid, 2D-honeycomb, 3D-honeycomb, and solid. Three-point flexural tests revealed that increasing the nozzle diameter from 0.4 mm to 0.8 mm significantly enhanced interlayer bonding, leading to a maximum improvement of 21.7% in flexural strength (Gyroid) and 25.3% in flexural modulus (solid infill). At 50% infill density, the 3D-honeycomb structure exhibited superior performance, with 4.7%-19.5% higher flexural strength and 2.89%-20.4% higher modulus than other infill types. Notably, the mass-normalized analysis highlighted the Gyroid structure as the most efficient in material utilization. With a 0.8 mm nozzle system, the strength could reach 14.11 MPa/g and the modulus could reach 574.24 MPa/g, highlighting its unique lightweight potential. Microscopic crack observations further elucidated the distinct failure mechanisms governed by the interplay between nozzle diameter and infill architecture. This work provided a comprehensive understanding of the process-structure-performance relationship in FDM-fabricated composites, offering practical guidelines for parameter selection in automotive lightweight applications.