Dammed nozzle: clogging of fiber suspensions at constrictions

Extruding fiber suspensions from nozzles is important in additive manufacturing to create strong, lightweight materials. However, these complex suspensions present significant fluid mechanics challenges during extrusion. In particular, fibers can clog the nozzle, causing system failures or defects in the final product. In this study, we use model 3D-printed nozzles to control their shapes and opening diameters. Experimentally, we extrude non-Brownian fiber suspensions, varying their volume fraction, length, and diameter, along with the nozzle diameter and suspension flow rate. We systematically characterize the suspension extruded from the nozzle to investigate the probability of nozzle clogging across these parameters. Using the experimental results, we provide some modeling to predict the occurrence of clogs and offer guidelines for optimizing extrusion to prevent nozzle clogging.