Structural imperfections in additive manufacturing perceived from the X-ray micro-tomography perspective

Our concern is to reveal the extent of structural imperfections of Additive Manufacturing (AM) by considering 3D imaging technique based on X-ray micro-tomography. Blocks of Acrylonitrile Butadiene Styrene (ABS) polymer are processed using Fused Deposition Modelling (FDM) with different printing orientations. Image analysis is applied to the stacks of 3D printed blocks to quantify structural attributes such as porosity content and connectivity. The results show that pore connectivity represents the most important structural characteristic of FDM. The adopted commercial solution is able to produce acceptable porosity contents below 6% regardless of the printing orientation. Finite element results indicate the presence of expected transverse symmetry. The examination of the extent of such anisotropy is in well agreement with the observed structural imperfections mainly the porosity content. However, these predictions do not match the wide variations in mechanical performance described in the literature. The finite element analysis guides the next research step towards quantification of the imperfect bonding nature between filaments in FDM. (C) 2016 Elsevier B.V. All rights reserved.