Effect of different parameters on the tensile properties of printed Polylactic acid samples by FDM: Experimental design tested with MDs simulation

Fused Depositional Modeling (FDM) is one of the common methods for 3D printing of polymers, which is expanding in various industrial applications, scientific researches, and engineering applications due to its ability to make complex parts. In this research, molecular dynamics (MDs) simulation has been used to predict the physical and mechanical properties. Then, the mechanical properties of the printed parts are obtained. The mechanical properties of 3D printed parts strongly depend on the correct selection of processing parameters. In this study, the effect of three important parameters such as infill density, printing speed, and layer thickness are investigated on the tensile properties of PLA specimens. For this purpose, standard specimens with four infill densities of 20%, 40%, 60% and 80%, two speeds of 20 mm/s, and 40 mm/s, and two thicknesses of 0.1 mm and 0.2 mm are printed and tested under quasi-static tensile test. In all printed specimens, the print angle is ± 45°. The experimental results show that the infill density in comparison to the other two parameters has significant effect on mechanical properties such as modulus of elasticity, ultimate strength, and failure strain. According to these results, by increasing the infill density, the stiffness and strength of the specimens increases considerably. At infill density of 80%, the specimens has the highest stiffness and strength, but it exhibits a brittle behavior. Moreover, it can be deduced that by reducing the layer thickness although the modulus of elasticity increases a little, ductility is greatly affected.