Characterizing the mechanical performances of fiber reinforced composites fused deposition modeling produced structural components for unmanned marine utilities

This study explores the mechanical performances of short-carbon-fiber-reinforced ABS composite specimens fabricated using fused deposition modeling (FDM) technology. Key process parameters, including printing nozzle diameter, internal infill pattern, and building orientation, were systematically analyzed to optimize mechanical properties. For flat specimens, increasing the nozzle diameter from 0.4 mm to 1 mm significantly enhanced interlayer bonding strength, resulting in notable improvements in bending strength and modulus. Among the infill patterns, fully filled configurations eliminated void defects and demonstrated superior load-bearing capacity, while gyroid structures offered lightweight advantages under specific nozzle systems. For L-shaped specimens, horizontal building orientation proved critical, delivering enhanced maximum load, curved beam strength (CBS), and interlaminar tensile strength (ILTS) compared to vertical orientation. The combination of larger nozzle diameters and horizontal orientation further improved extrusion flow rates and interlayer bonding quality, making this configuration particularly suitable for marine applications like catamaran connectors. A mass-normalized evaluation framework highlighted the lightweight potential of gyroid infill patterns, emphasizing their development prospects in marine engineering. Microscopic observations revealed the interplay between process parameters, microstructure, and mechanical performance, with nozzle diameter influencing failure modes and infill patterns regulating load transfer paths. These findings advance the understanding of process-structure-performance relations of FDM-printed fiber-reinforced composites and open new opportunities for lightweight, high-strength designs tailored to marine systems, renewable energy, robotics, and modular infrastructure.