Controlling toughness and strength of FDM 3D-printed PLA components through the raster layup

We investigate the influence of raster layup on the resulting material properties of FDM 3D-printed materials made of PLA. In particular, we investigate the resulting toughness, strength, and stiffness, with a special focus on toughness. We show that for standard layups with layer orientations alternating by 90 degrees, stiffness and strength are almost isotropic, while a strong anisotropy is obtained for toughness. Moreover, we show that materials with such a layup can even switch their behavior from brittle to ductile depending on the loading direction. Finally, we propose a new layer stacking scheme which simultaneously provides increased toughness and increased strength compared to the standard approaches.