Unified experimental and finite element analysis of the mechanical performance of 3D-printed honeycomb and auxetic sandwich cores

A critical challenge in the design of lightweight composite structures is the quantitative selection of core architectures for specific loading conditions. This study presents an integrated experimental–numerical investigation into the performance of 3D-printed sandwich composite cores, focusing on honeycomb and auxetic architectures fabricated via fused deposition modeling (FDM) using PLA+. Mechanical performance was characterized under compression, three-point bending, and Charpy impact, following relevant ASTM standards. Finite Element Analysis (FEA) in Abaqus was validated through mesh convergence and energy balance checks, ensuring robust simulation fidelity. Statistical analysis using a two-way ANOVA revealed a significant interaction effect between core geometry and load type (F(2,12) = 15.14, p < 0.001), indicating that auxetic cores exhibit ∼51 % higher specific energy absorption (SEA) than honeycomb cores in compression, while honeycomb cores provide superior flexural stiffness, and performance differences narrow under impact. The proposed methodology, while demonstrated with PLA+, is applicable to other core materials, enabling data-driven selection of composite core designs for application-specific requirements.