Stress-Guided Localized Infill Variation for Improving the Mechanical Efficiency of FDM-Printed L-Bracket Structures

Fused deposition modeling (FDM) enables spatial control of internal infill, but uniform infill neglects the nonuniform stress distribution governing failure. This study evaluates a finite element analysis (FEA)-guided, stress-based infill distribution strategy for FDM-printed L-brackets. FEA defined low-, intermediate-, and high-stress regions, implemented as uniform, two-region, and three-region infill configurations. PLA specimens were assessed experimentally in terms of failure load, specimen mass, specific failure load, printing time, and estimated energy consumption. Stress-guided infill distribution increased absolute failure load relative to uniform-infill baselines, but the highest absolute failure load did not necessarily correspond to the most efficient configuration. Mass-normalized analysis demonstrated that moderate two-region configurations achieved the highest specific failure load, outperforming both uniform and three-region configurations. Increasing infill segmentation or excessive density gradients did not yield proportional improvements in mechanical strength. Overall, moderate two-region stress-guided infill distribution provided the most favorable balance between mechanical strength, material usage, and estimated energy demand. The findings demonstrate that FEA-guided infill distribution can improve the efficiency of FDM-printed components rather than simply increasing the overall infill density.