Modelling of material deposition in big area additive manufacturing and 3D concrete printing

Big area additive manufacturing and 3D concrete printing are two technologies that upscale the material extrusion additive manufacturing concept to larger workpiece dimensions and higher build rates. This work presents a computation fluid dynamics model that simulates material extrusion and deposition using the software FLOW-3D. The numerical simulation is used to evaluate the cross-sectional shape of the printed beads. Several constitutive models have been considered to cover the wide range of material behaviours, including shear-thinning and visco-plasticity, that are expected in the flow of molten plastic and fresh concrete. The presence or absence of shear-thinning was found to have more influence on the cross-section of the bead than the actual values of the viscosity. The numerical results are also compared to the nominal bead’s dimensions used in slicer softwares. The conclusion of this study is that the actual bead’s dimensions can vary substantially from its nominal size, which is one of the phenomena that affects negatively the manufacturing precision.