A Comparative Study on the Influence of Stacking Sequence, Infill Ratio, and Infill Pattern on the Impact Performance of Functionally Layered <scp>PLA</scp> and <scp>PETG</scp> Fabricated by Additive Manufacturing

ABSTRACT Understanding the impact performance of fused deposition modeling (FDM) components is critical for their reliable application in load‐bearing and safety‐sensitive structures. This study provides a comprehensive experimental investigation into how mesostructural parameters—specifically infill ratio, infill pattern, and stacking configuration—influence the behavior of FDM‐printed PLA and PETG under impact loading. Charpy impact tests were conducted on identical‐layer and multilayered specimens fabricated with varying infill strategies, enabling a comparative evaluation of impact strength. The results demonstrate that mesostructural parameters play a more decisive role in governing impact behavior than the intrinsic properties of the base polymers. Among the tested configurations, PETG specimens with a 100% infill ratio and a trihexagon pattern achieved the highest impact strength of 32 kJ/m 2 , while PLA samples with 20% infill ratio and a gyroid structure exhibited the lowest value of 16.9 kJ/m 2 . The trihexagon pattern consistently provided the highest impact resistance, while zigzag and gyroid patterns performed poorly, especially at low infill ratios. Higher infill ratios enhanced absolute impact strength, whereas lower infill ratios improved specific impact strength, offering a lightweight advantage. The comparative analysis revealed that multilayered K2 configurations exhibited superior resistance to crack propagation, accompanied by a more stable fracture response relative to the K1 designs. Notably, the best specific impact strength among multilayered specimens was achieved by trihexagon‐based K1 models, reaching 31.5 J m 3 /kg m 2 for PETG and 30 J m 3 /kg m 2 for PLA. These findings highlight the critical role of mesostructural optimization in tailoring lightweight, high‐performance polymer components produced by additive manufacturing.