Predicting homogenized mechanical properties of 3D FFF-printed grid infills via multi-scale simulation

Purpose This study aims to find the homogenized mechanical response of fused filament fabrication (FFF) components containing infill. More importantly, promotes a methodology to predict the elastic properties owing to microscopic fabrications. Design/methodology/approach Cubic specimens fabricated from polylactic acid (PLA) were manufactured over five infill densities (20%, 40%, 60%, 80% and 100%) and two raster angles (−45°/45° and 0°/90°). Quasi-static compression tests were conducted to evaluate the homogenized elastic modulus (E) along three orthogonal directions. The multi-scale finite element modeling used a periodic boundary condition (PBC) formulation to compute the effect of voids (microscale unit cell) and layer deposition direction (mesoscale unit cell) on the behavior of a cubic specimen (macroscale unit cell). Findings The trend of Young’s modulus with increasing infill density for both cell arrangements is the main result. The representative volume element method using PBC was able to precisely predict infill structures’ elastic responses and shows a good agreement with experimental results. Originality/value The multidirectional experimental method provides a comprehensive perspective of the structures, and the conducted simulation in comparison to previous studies reduces the modeling challenges and computational effort effectively. This method not only quantifies the stiffness relations in three directions, but also uses step-wise simulation to provide the reason for the difference.