Elsevier

Additive Manufacturing

Volume 46, October 2021, 102129
Additive Manufacturing

3D printing non-cylindrical strands: Morphological and structural implications

https://doi.org/10.1016/j.addma.2021.102129Get rights and content
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Highlights

  • 3D printing with new strand cross-section geometries to enhance concavity and specific surface area.

  • Evaluating the extrusion shape fidelity and ink’s rheology.

  • Analysing through finite elements method the load distribution of the different structures.

  • Investigating the phenomena of strand deposition stability and torsion throughout the printing path and configuration.

Abstract

Conventional direct ink writing uses circular nozzles and, therefore, results in cylindrical strands. 3D printing with non-circular nozzles adds new degrees of freedom to this versatile technology, and allows obtaining structures with higher specific surface area or even introducing concave surfaces in the printed architecture. This is an enticing prospect for countless applications, including tissue engineering, chemical reaction catalysts, water evaporators and electrochemical energy storage devices. Despite this, it has been hardly explored by the 3D-printing community. Herein, we develop for the first time 3D printed structures with complex filament section morphologies using a custom-made modular nozzle and a self-setting ceramic ink. The fast elastic recovery of the ink allows obtaining good shape fidelity in the printed filaments, permitting the creation of intricate surfaces with up to 30% concavity and increasing up to 2.5 times the specific surface area compared to cylindrical strands. The use of non-circular nozzles introduces some specific constraints in the printing process. The geometry of the nozzle determines the stable printing directions, and nozzle orientation becomes a critical parameter to achieve a stable printing. Strand torsion, a phenomenon that remains unnoticed with circular nozzles, may result in relevant changes in the geometrical features of the printed structures.

Keywords

Direct ink writing
Microextrusion
Robocasting
Ceramic
Calcium phosphate

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