Influence of lattice-core geometry on the mechanical performance of FDM-printed PETG sandwich panels: an experimental, computational, and statistical investigation

Abstract This study aims to find the impact of lattice-core geometry on the tensile and flexural properties of FDM-printed PETG-sandwich panels. Six core profiles (namely square, circular, elliptical, octagonal, pentagonal and hexagonal) were fabricated under controlled parameters of the FDM and tested based on ASTM D638 and D790. The pentagonal core resulted in the highest flexural strength (23.2 MPa), peak load (322 N), and the hexagonal core in the highest tensile strength (24.8 MPa). The variation in tensile and flexural strength was highly explained by core geometry (93.4% and 93.8% respectively) (ANOVA, $$p<0.001$$ ). The Taguchi S/N ratio evaluation demonstrated that both tensile and flexural performances exhibit comparable high sensitivity to core geometry variations (a relative difference of approximately 2.5%). A flexural strength was predicted by an elastic–plastic FEA model created in ABAQUS/CAE, with an error margin of 4.1% when compared to experimental results. These PETG panels experienced a strength loss of 12–16% but a 58–63% increase in ductility when compared to PLA + panels with the same core topology, demonstrating that core topology dictates performance across the evaluated thermoplastic matrices. The results will be useful for quantitatively suggesting the topology for FDM-fabricated sandwich structures.