Quasi-static and low-velocity impact bending performance of additively manufactured polymer-matrix composites: Role of filament architecture

<p dir="ltr">Additive manufacturing (AM), particularly extrusion-based 3D printing, enables the fabrication of fibre-reinforced composites with complex geometries, tailored architectures, and reduced waste. Compared to conventional composites, AM counterparts offer localised property control and rapid prototyping, yet their dynamic response remains underexplored. This study investigates the quasi-static and low-velocity impact bending of nylon-based AM composites reinforced with short and continuous carbon fibres. The effects of fibre type (short vs. continuous) and orientation (longitudinal, transverse, quasi-isotropic) were examined using three-point bending and pendulum impact tests at multiple energy levels. In addition, repeated-impact experiments were performed to assess durability and progressive damage. The obtained results show that fibre architecture strongly influences stiffness, strength, and energy absorption. Short-fibre composites exhibited higher initial flexural stiffness, while continuous-fibre laminates delivered superior strength and impact resistance. Under intermediate impacts, quasi-isotropic short-fibre configurations achieved a favourable balance between toughness and damage tolerance, despite their lower strength. At higher energies, continuous-fibre laminates absorbed more energy through complex fracture propagation. These findings highlight the importance of fibre continuity and orientation in tailoring the mechanical response and provide insight into the design of AM composites for impact-sensitive applications where toughness, manufacturability, and cost-effectiveness must be balanced.</p>