Geometric characterization of orthogonally printed layers in material extrusion additive manufacturing: numerical modeling and experiments

This study shows how a computational fluid dynamics (CFD) model can be used as a complementary approach to investigate the influence of processing parameters on the morphology of printed strands, in material extrusion additive manufacturing (AM). Experimental investigations were also realized to validate the numerical model. Both experiments and numerical simulations were employed to quantify the deformation of a molten polymeric strand extruded on top of an uneven substrate constituted of previously printed parallel strands. This configuration occurs when a structure is printed with a rectilinear infill pattern and alternate raster angles from layer to layer. The deformation of the molten strand is mainly influenced by the gap distance between the strands of the previous layer and the speed ratio of the nozzle displacement to the extrusion volumetric flux. Numerical simulations are able to capture variations in the strand’s shape, under different printing conditions. Finally, the numerical model also provides an estimate of the interlayer contact area, which was not possible to measure in experiments, but constitutes a critical parameter for the mechanical properties of 3D-printed parts.