Filament path optimization of Fused Filament Fabricated parts incorporating the effect of pre-fusion densities

Fused Filament Fabricated parts exhibit mechanical anisotropy induced by the filament extrusion pattern and possibly due to the intrinsic nature of feedstock material. Consequently, an optimized filament deposition strategy is desirable for improving the part's functionality. The present work optimizes the in-plane filament paths of Fused Filament Fabricated parts to strengthen component load-bearing capacity, with a particular focus on obtaining production-ready design solutions through a direct imposition of the manufacturing constraints. To perform an effective in-plane filament path optimization, the present contribution also addresses, among several other aspects, the following: (i) the development and implementation of a new material model that incorporates the transverse stiffness loss in the absence of inter-filament fusion, and (ii) a comparative study between a two-step gradient-based minimization and a global metaheuristic minimization. The results indicate that the new material model yields more realistic filament patterns compared to the assumption of neglecting the transverse stiffness loss at low filament densities. Further, the comparison of optimization approaches suggests the preference for the two-step gradient-based approach due to its better efficiency, flexibility, and compatibility with the proposed material model.