3D Printed Continuous Fiber‐Polymer Composites: Fiber Damage and Mechanical Property Reductions Caused by Fused Deposition Modeling

ABSTRACT Material extrusion (ME) enables additive manufacturing of continuous fiber‐polymer composites, with carbon, glass, and aramid fibers being the most widely used reinforcements. This study systematically investigates the fiber damage mechanisms in these three filament types during ME‐based 3D printing. Fiber damages initiate as the filaments feed through the 3D printer and intensify during deposition on the platform. The extent and modes of damage correlate strongly with inherent fiber properties. Carbon fibers, characterized by low toughness and failure strain, sustain the most severe damage and breakage, resulting in 21% and 42% reductions in filament stiffness and strength, respectively. Glass fibers also suffer breakage during fabrication, although the extent is less pronounced compared to carbon fibers, with the filament stiffness and strength reduced, respectively, by 15% and 32%. Aramid fibers, while resistant to breakage due to high toughness and ductility, undergo crimping and a 15% strength loss. Such damages induced by 3D printing significantly compromise the tensile properties of fabricated laminates. The study highlights the critical roles of fiber bending stiffness, fracture toughness, and failure strain in achieving minimal fiber damage and optimizing the mechanical performance of 3D printed continuous fiber composites.