Investigation of the tensile strength properties of pla parts produced by additive manufacturing depending on the printing orientation

In this study, the effect of printing orientation on the mechanical properties of polylactic acid (PLA) specimens produced by the Fused Deposition Modeling (FDM) method was investigated experimentally and numerically. Tensile specimens conforming to the ASTM D638-14 standard were manufactured using a ZAXE X1 PLUS 3D printer and PLA-ZAXE filament (Ø 1.75 mm). The specimens were printed in flat and upright orientations with a ±45° raster angle and a constant layer thickness of 0.15 mm. Tensile tests were carried out at room temperature using a Shimadzu AG-IS 250 kN testing machine under a strain rate of 1.4 × 10⁻³ s⁻¹. From the obtained stress–strain curves, the elastic modulus, yield behavior, ultimate tensile strength, and elongation at break were determined. In addition to the experimental study, numerical analyses were performed for the same specimens using the finite element method, and the numerical results were compared with the experimental data. The results indicate that PLA specimens printed in the flat orientation exhibit higher strength and ductility compared to those printed in the upright orientation. This behavior demonstrates that the relationship between the layer deposition direction and the applied loading direction has a decisive effect on the mechanical performance of PLA parts.