Subvoxel control of fiber orientation via multidirectional shearing in 3D printing

Abstract Anisotropy, the characteristic of materials exhibiting different properties based on their direction1,2,3,4, is widespread in nature. Conventional manufacturing techniques5 often fall short in recreating such complex, localized anisotropy6,7,8. On the other hand, 3D printing allows for precise fiber deposition when producing anisotropic composites9,10,11,12. However, current methods are not able to produce fiber configurations in all three directions on a strand level, preventing full replication of the intricate anisotropy found in natural materials. To address this, we present a novel technique that provides subvoxel control using multidirectional shearing through nozzle rotation and inclination in the material extrusion additive manufacturing process. This approach allows for uniquely manipulated microstructures within a strand, indistinguishable to the naked eye. We outline the re-orientation mechanisms of fibers and demonstrate through experiments and computational simulations the effects of different process parameters on fiber configurations. This includes scenarios with fibers transversal to the print direction and local near-isotropic regions. Replicating such complex anisotropy holds potential across several fields, including wearables13,14 and biomedical implants15, lightweight composite structures16, and energy storage technologies such as batteries and supercapacitors17,18.