Ultrasound-assisted vat photopolymerization 3D printing of preferentially organized carbon fiber reinforced polymer composites

In this study, we present a new vat photopolymerization 3D printing process that uses acoustic radiation forces from ultrasonic standing waves to organize carbon short fibers within a photocurable resin. A chamber was developed to generate the standing bulk acoustic wave in the resin to align the carbon fibers along the nodes of the standing wave. The resin was then selectively cured to create constructs in the shape of a dog bone specimen by exposing to UV. The effect of fiber concentration (0.5 %, 1 %, 2 %, and 4 % w/v) and direction of alignment (parallel, perpendicular) on tensile strength of the carbon fiber reinforced polymer composites was determined. The constructs with 1 % w/v showed the highest gain in tensile strength due to the fiber alignment. For two-layered constructs with 1 % fiber concentration, 0 degrees-0 degrees constructs (fibers aligned along the uniaxial testing direction) demonstrated significantly higher tensile strength followed by 0 degrees-90 degrees constructs compared to constructs with randomly distributed fibers and without fibers.