Stability and deformations of deposited layers in material extrusion additive manufacturing

Md Tusher Mollah*, Raphaël Comminal, Marcin P. Serdeczny, David B. Pedersen, Jon Spangenberg

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

This paper presents computational fluid dynamics simulations of the deposition flow during printing of multiple layers in material extrusion additive manufacturing. The developed model predicts the morphology of the deposited layers and captures the layer deformations during the printing of viscoplastic materials. The physics is governed by the continuity and momentum equations with the Bingham constitutive model, formulated as a generalized Newtonian fluid. The cross-sectional shapes of the deposited layers are predicted, and the deformation of layers is studied for different constitutive parameters of the material. It is shown that the deformation of layers is due to the hydrostatic pressure of the printed material, as well as the extrusion pressure during the extrusion. The simulations show that a higher yield stress results in prints with less deformations, while a higher plastic viscosity leads to larger deformations in the deposited layers. Moreover, the influence of the printing speed, extrusion speed, layer height, and nozzle diameter on the deformation of the printed layers is investigated. Finally, the model provides a conservative estimate of the required increase in yield stress that a viscoplastic material demands after deposition in order to support the hydrostatic and extrusion pressure of the subsequently printed layers.
Original languageEnglish
Article number102193
JournalAdditive Manufacturing
Volume46
Number of pages20
ISSN2214-8604
DOIs
Publication statusPublished - 2021

Keywords

  • Viscoplastic Materials
  • Material Extrusion Additive Manufacturing (MEX-AM)
  • Multiple-Layers Deposition
  • Computational Fluid Dynamics (CFD)
  • Deformation Control

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