Simulated filament shapes in embedded 3D printing

Published

July 22, 2021

Author(s)

Leanne Friedrich, Jonathan Seppala

Abstract

Embedded 3D printing, wherein fluid inks are extruded into a bath, has enabled the manufacture of complex, custom structures ranging from cell-laden tissue analogues to soft robotics. This method encompasses two techniques: embedded ink writing (EIW), where filaments are extruded, and embedded droplet printing (EDP), where droplets are suspended. Materials for embedded 3D printing can be Newtonian, but often both the ink and the support bath are yield stress fluids, following elastic behavior below the yield stress and shear thinning, viscous behavior above the yield stress. Inks have been printed into supports at high and low surface tensions. In order to guide material selection for embedded 3D printing and identify key scaling relationships that influence print quality, this study investigates the role of ink rheology, support rheology, and surface tension on the morphology of single filaments. Numerical simulations in OpenFOAM demonstrate that at low viscosities, surface tension controls the filament morphology. Where capillarity is suppressed, the ratio of the local ink and support viscosities and the shape of the yield surface in the support control the filament shape. Herschel-Bulkley support fluids produce more stable, accurately positioned filaments than Newtonian supports. In the short term, non-zero surface tensions can suppress filament shape defects in EIW and are essential for producing droplets in EDP.

Citation

Soft Matter

Volume

17

Pub Type

Journals

Download Paper

https://doi.org/10.1039/D1SM00731A

Local Download

Keywords

3D-printing, extrusion, support-bath, Herschel-Bulkley, rheology, surface tension, OpenFOAM

Citation

Friedrich, L. and Seppala, J. (2021), Simulated filament shapes in embedded 3D printing, Soft Matter, [online], https://doi.org/10.1039/D1SM00731A, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932313 (Accessed May 10, 2024)