A smoothed particle hydrodynamics study of a non-isothermal and thermally anisotropic fused deposition modeling process for a fiber-filled composite

<jats:p>A smoothed particle hydrodynamics method is employed to study the mechanical and thermal behaviors of a fiber-filled composite with an anisotropic thermal conductivity (which is coupled to the orientation of the fibers) in a three-dimensional printing process for one- and two-layer deposition. Using a microstructure-based fiber suspension model with a fiber orientation-dependent thermal conductivity model, a temperature-shear-thinning viscosity model, and a microstructure constitutive model, the effect of the nozzle temperature on the fiber alignment when printing one layer and the mechanical and thermal interactions between two printed layers are investigated. It is found that the anisotropic thermal conductivity (fiber-orientation-dependent) enhances the fiber alignment in the printing direction in the upper half layer and reduces it in the lower half at a relatively high fiber concentration (Φ = 0.2). For the one-layer deposition, the fiber alignment in the printing direction is enhanced in the lower half of the layer with an increase in the nozzle temperature. This tendency is more pronounced with the increase in both the fiber concentration and the aspect ratio. On the two-layer deposition, the fiber alignment of the first layer experiences a “reciprocating” evolution due to the squeezing from the second layer, thus creating an enhancement in the upper half and a reduction in the lower half in the fiber alignment in the first layer (with respect to the printing direction). Increasing the fiber concentration or the aspect ratio amplifies this variation for the first layer. Increasing the substrate velocity also leads to some variations in the fiber alignment.</jats:p>