Compressive response of 3D-printed PETG and PETG-CF honeycomb structures: Experimental and numerical investigation

Abstract

Honeycomb structures have attracted growing interest for lightweight applications due to their geometric flexibility, high specific stiffness, and energy absorption capability. In this study, the compressive response of 3D-printed honeycomb structures made from neat polyethylene terephthalate glycol (PETG) and short carbon fiber-reinforced polyethylene terephthalate glycol (PETG-CF) was investigated through integrated experiments and finite element simulations. Tensile tests based on ASTM D638 were conducted to characterize the material behavior, while flatwise compression tests following ASTM C365 were performed on the honeycomb specimens. Although PETG-CF exhibited higher tensile strength and stiffness than neat PETG, its honeycomb structures showed lower specific energy absorption under compression. Numerical models calibrated using tensile-derived material parameters successfully reproduced the main deformation stages, including elastic response, buckling, and densification, with predicted energy absorption values within 10% of the experimental results. The lower compressive performance of PETG-CF is attributed to reduced ductility, earlier localized buckling, and more restricted cell-wall folding. These findings show that improved tensile properties at the material level do not necessarily lead to superior compressive performance at the structural scale.