The effects of layer deposition angle and layer temperature on the orthotropic mechanical properties of 3D printed PLA parts

The mechanical properties of fused filament fabrication, FFF, additive manufactured parts are strongly affected by the specific printing parameters. Previous work in 3D printed PLA characterization under quasi-static tensile loading has focused on the effect of build-orientation and infill geometry. The present work focuses on the effect of layer temperature as controlled by layer printing time and cooling fan setting on the uniaxial tensile properties of 3D printed PLA for 100% and 40% linear infill prints at various print angles. As previously found, for a given print temperature, build orientation has a significant effect on tensile strength and elastic modulus, with both parameters increasing as build angle increases. However, layer temperature plays a critical role in both elastic modulus, tensile strength and ductility. All these three parameters significantly increase with layer temperature for the range of temperature tested in this study (between approximately 40ºC and 105ºC). The experimental results were used to derive a transversely isotropic, theoretical model based on classical laminate theory and the Tsai-Hill’s failure criteria at each temperature, and were implemented in a finite element model (FEM). The FEM captured the overall experimental tensile behavior of both the 100% infill and 40% linear infill cases