Numerical multiscale analysis of 3D printed short fiber composites parts: Filament anisotropy and toolpath effects

Abstract

The aim of the present investigation is the development of a numerical model able to adequately represent the effect of several variables, associated to the fused deposition modeling (FDM) procedure, on the mechanical behavior of 3D printed parts. Specifically, 3D printed carbon short-fiber reinforced thermoplastic parts are numerically analyzed. Previous experimental results have proven that this kind of parts show a global anisotropic behavior, in terms of classical mechanical parameters as stiffness. Thus, special emphasis is done in analyzing the effect of the raster angle / toolpath (inherent to FDM) and the internal microstructure of the deposited filaments (due to the presence of the short fibers). Multiscale finite element models are used to represent the linear elastic behavior at macro scale. The numerical models are also able to include the effect of porosity. Based on experimental results of 3D printed composite parts with 100% infill and different raster angles, elastic transversely isotropic properties are estimated for the individual deposited filaments using a reverse engineering procedure. Obtained results show that for an adequate modeling of FDM composite parts, anisotropic properties of the filament must be taken into account, even when quasi-isotropic printing parameters are used (“cross-ply” configurations). Finally, additional numerical analyses of some parameters associated to the FDM technique are done. Specifically, the effect of porosity related to the infill pattern and percentage on the global (macro) apparent stiffness is analyzed.