Experimental and numerical study of orthotropic behavior of 3D printed polylactic acid by material extrusion

The advantages of 3D printing technology will continue to ensure the growth and importance of this manufacturing technique. Improving the mechanical properties and the understanding of the anisotropic behavior of 3D printed parts are some of the main challenges of Additive Manufacturing. The aim of this work is to study the effect of printing speed on the orthotropic behavior of polylactic acid (PLA) manufactured by Fused Deposition Modeling (FDM), also known as material extrusion (ME). 80 tensile tests were made on samples printed with printing speeds from 40 to 145 mm/s, and print directions were longitudinal and transverse. A new numerical method based on a trial of finite element simulations is proposed to find the Poisson's ratios of the orthotropic PLA manufactured by FDM. The mesh was made with Gmsh® and processing with Calculix®. The PLA was simulated as an elastic orthotropic material. Experimental measurements and numerical analysis show that the Poisson’s ratio perpendicular to the load decreases lightly with the printing speed and changes strongly with the print direction. The new numerical method proposed describes exactly the mechanical behavior of 3D printed parts manufactured by FDM with a longitudinal concentric fill partner, therefore the elastic behavior of 3D printed parts of PLA manufactured by FDM can be simulated as Elastic Orthotropic Material.