Mechanical strength of 3D-printed lattices under different environmental conditions

In this study Additive Manufacturing (AM, i.e., 3D printing) has been used for fabrication of lattices with three different geometries: honeycomb, fourfold, and re-entrant. The specimens were fabricated based on the material extrusion technique, using Polyethylene Terephthalate Glycol (PETG) filament, which was reinforced with short carbon fiber additives. Since 3D-printed components might be subjected to various environmental conditions during their service life, here some of the test coupons were artificially aged (-5 to 40 °C) to determine effects of this thermal aging on their mechanical behavior. Based on a series of mechanical tests on the aged and unaged specimens, the deformation and energy absorption capabilities of the specimens were compared. Parallel to the experiments, two dimensional Finite Element Model (FEM) was developed to evaluate the mechanical performance and investigate the stress distribution and plastic deformation of the examined lattice structures. Moreover, Fractography analysis was conducted using Scanning Electron Microscope (SEM) images. The experimental findings indicate that energy absorption until damage initiation and energy absorption until the densification have been increased in almost all specimens due to the conducted thermal aging. In addition, SEM images indicate that during the loading process a higher amounts of energy was dissipated in the aged re-entrant lattices structure, compared to unaged test coupons. The documented results can be used for design and fabrication of thermal-stable 3D-printed composite parts.