Effect of Infill Structure on Mechanical Properties of 3D Printed Components

Abstract

This paper deals with experimental determination of the influence of internal infill geometry and its density on the mechanical properties of 3D printed components made from thermoplastic PET-G material. Tensile tests were performed on 33 specimens prepared according to DIN EN ISO 527 standard, testing five standard infill structures (rectilinear, honeycomb, gyroid, cubic, line) at densities of 15% and 30%. Specimens were manufactured using FDM technology with constant printing parameters on an Instron 3382 testing machine. Results showed that honeycomb structure at 30% density achieved the highest tensile strength of 36.8 MPa, while the transition from 15% to 30% density brought an increase in strength of 85-102% for all tested geometries. Gyroid structure exhibited the most balanced ratio of strength (33.1 MPa) and deformability (5.50%), making it suitable for cyclic loading applications. Fractographic analysis confirmed interlaminar delamination as the primary failure mechanism. The study demonstrated that selection of optimal internal structure significantly affects mechanical properties of 3D printed parts, with honeycomb or cubic structures at minimum 30% density recommended for applications requiring high tensile strength.