Numerical modeling of fiber orientation in additively manufactured composites

Additive manufacturing has undergone a significant transformation, evolving from a mere prototyping technique to a reliable and proven manufacturing technology that can produce products of varying sizes and materials. The incorporation of fibers in additive manufacturing processes has the potential to improve a range of material properties, including mechanical, thermal, and electrical properties. However, this improvement is largely dependent on the orientation of the fibers within the material, with the properties being enhanced primarily in the direction of fiber orientation. As a result, accurately predicting and controlling the fiber orientation during the extrusion or deposition process is critical. Various methods are available to control fiber orientation, such as manipulating the nozzle shape, extrusion and nozzle speed, the gap between the nozzle and substrate, as well as fiber features like aspect ratio and volume fraction. At the same time, the presence and orientation of fibers can significantly impact the flow pattern and extrusion pressure conditions, ultimately affecting the formation of printed strands in a manner distinct from those without fibers. For that reason, our study utilizes computational fluid dynamics to anticipate and comprehend the printing conditions that would result in favorable fiber orientations and strand shapes, incl. corner printing. Our findings may be utilized to determine optimal toolpaths for 3D printing composites, as well as printing conditions that will facilitate the achievement of the desired fiber orientation within individual strands.