The effects of fiber orientation on stiffness and thermal expansion of large volume, anisotropic, short-fiber, composite material fabricated by Fused Filament Fabrication.

Fused Filament Fabrication (FFF) is a rapidly improving 3D printing technology that can be used for manufacturing complex parts. The properties of these parts can be improved by adding short-fibers to the polymer feedstock. The fiber orientation state is critical to know in order to determine the final material properties though. This study investigates the reasonableness of several fiber orientation models based on their use in predicting the effective longitudinal Young’s modulus E_22 and CTE α_22 of a large volume, short-fiber composite, FFF printed bead. Comparisons are made between computational results from MATLAB (MathWorks, Inc., Natick, MA) and COMSOL Multiphysics (Stockholm, Sweden) to experimental results from samples collected from beads fabricated with an in-house, large scale bead deposition system. Based on comparisons of the computational and experimental results for E_22 and α_22, the Reduced Strain Closure (RSC) model [1] with 1/30≤κ≤1/5 seems to be the most reasonable.