Screw Swirling Effects on Fiber Orientation Distribution in Large-Scale Polymer Composite Additive Manufacturing
Large-Scale Additive Manufacturing (LSAM) polymer deposition employs a single screw extruder to melt and deliver the pelletized feedstock resulting in significantly higher flow rates as compared to conventional filament-extrusion AM processes. Single screw swirling motion in the melt flow during processing generates a unique pattern of flow-induced fiber alignment when fiber-filled polymer feedstock is processed. This paper investigates the effect of the single screw swirling motion on the fiber orientation and predicted elastic properties of a printed extrudate. A finite element extruder nozzle flow is created, where the extruder screw tip, the extrusion nozzle, and a short section of free extrudate compose the melt flow domain. The IRD-RSC fiber orientation diffusion model is applied to capture the slow orientation kinetics of short fibers in the concentrated fiber suspension. The results indicate that the swirling motion of the flow has a direct effect on predicted fiber orientation distribution and the associated averaged elastic properties in the extruded composite bead.