Effects of Fiber Orientation on the Bearing Strength of 3D-Printed Composite Materials Produced by Fused Filament Fabrication.

Among 3D printing technologies, fused filament fabrication (FFF) is a fast, simple, and low-cost technology that is being explored in a variety of industries. FFF produces composites using thermoplastic filaments, limiting the applicability of welding. Therefore, mechanical fastening is required to join FFF composites with metals or dissimilar materials. The strength characteristics of fastened joints vary with fiber orientation, necessitating further research. Additionally, in the case of FFF, the strength trends may differ from those of traditional composites due to the voids and curved surfaces formed during the process. In this study, 3D-printed composite specimens with seven different fiber orientations were fabricated using the Markforged X7™ printer. The bearing strength and failure modes were analyzed as a function of fiber orientation. Unlike traditional composites, specimens with a ±15° fiber orientation exhibited a 7.56% higher bearing strength compared to those with a 0° orientation. However, the fracture energy of the ±15° specimens was 39.56% lower. Specimens with fiber orientations between 0° and ±45° primarily showed bearing failure modes, while those with orientations from ±60° to 90° exhibited net-tension failure modes. These results confirm that when using manufacturing methods like FFF, the strength trends vary with fiber orientation compared to traditional composites. Further research is necessary to optimize fiber orientation and improve structural performance.