Numerical and Experimental Characterisation of Polylactic Acid (PLA) Processed by Additive Manufacturing (AM): Bending and Tensile Tests

In additive manufacturing (AM), one of the most popular procedures is material extrusion (MEX). The materials and manufacturing parameters used in this process have a significant impact on a printed product’s quality. The purpose of this work is to investigate the effects of infill percentage and filament orientation on the mechanical properties of printed structures. For this reason, the characterisation of polylactic acid (PLA) was done numerically using the finite element method and experimentally through mechanical tests. The experiments involved three-point bending and tensile tests. The results showed that mechanical performance is highly dependent on these processing parameters mainly when the infill percentage is less than 100%. The highest elastic modulus was exhibited for structures with filament align at 0° and 100% infill, while the lowest one was verified for specimen filament aligned at 0° and 30% infill. The results demonstrated that the process parameters have a significant impact on mechanical performance, particularly when the infill percentage is less than 100%. Structures with filament aligned at 0° and 100% infill showed the maximum elastic modulus, whereas specimens with filament oriented at 0° and 30% infill showed the lowest. The obtained numerical agreement indicated that an inverse method based only on the load–displacement curve can yield an accurate value for this material’s elastic modulus.