Study on 3D printing of gyroid-based structures for superior structural behaviour

The use of low-cost fused filament fabrication (FFF) machines has been growing in the last years. Being widely used in the industry, the biggest challenges for FFF machines is the difficulty to predict quantitatively the influence of the printing parameters on the printed parts and, consequently, on the printed surface of foam lattices. Such variability hinders the prediction of the structural behaviour of printed materials and parts. Recent studies have shown that gyroid-based structures allow higher structural performances. Such complex geometry, used in distinct pattern distributions, is now possible to be widely produced with additive manufacturing (AM) technologies. This work aims to study the influence of this inner infill geometry on the mechanical properties of PLA parts. Thus, experimental specimens for tensile, compression and bending tests were printed in a 3D printer (Creality Ender3) with $$100\%$$ infill and four different orientations: (1) $$0^{\circ }$$ ; (2) $$45^{\circ }$$ ; (3) $$\pm 45^{\circ }$$ ; and (4) $$90^{\circ }$$ . Additionally tensile, bending, compression, Charpy and impact specimens were printed in a 3D printer based on a Creality CR-10S with gyroid infill and three different densities: (1) $$20\%$$ ; (2) $$50\%$$ ; and (3) $$80\%$$ . Both groups of specimens were tested and the gyroid structure properties were also investigated. The results show that the best tensile and bending properties were obtained when the filament has the same orientation as the load. Furthermore, the mechanical properties and the weight increased with the gyroid infill density. Finally, the influence of outside perimeters on specimens under compression was constant. It was found that the gyroid structure presents low anisotropy under compression and it was demonstrated that the inner foam structure and pattern (in this case the gyroid structure) is more relevant than the material used to build structural part.