A Critical Analysis of Young's Modulus Determination for Fused Filament Fabricated Polylactic Acid Specimens

This research investigates the influence of key Fused Filament Fabrication (FFF) process parameters on the tensile properties of Polylactic Acid (PLA). Dog-bone specimens, compliant with ISO 527-2, were printed in three distinct build orientations and at two extrusion temperatures. Uniaxial tensile tests were performed to determine the Ultimate Tensile Strength, Elongation at Break, and Young's Modulus. The results demonstrate the significant anisotropic mechanical behaviour of FFF-printed PLA, with vertically oriented specimens exhibiting the highest strength. A critical analysis of methodologies for determining material stiffness was also conducted, comparing the standard ISO 527 Young's Modulus against a Linear Regression approach and a novel Dynamically calculated Young's Modulus method that identifies the most stable elastic region. Findings reveal that the calculation method significantly impacts the resulting Young's Modulus, with the standard chord method overestimating stiffness by up to 14% compared to the more robust data-driven approaches. This study underscores the critical importance of both process parameter control and the selection of an appropriate analysis methodology for the accurate mechanical characterization of additively manufactured components for engineering applications. Fused Filament Fabrication (FFF), Polylactic Acid (PLA), Young's Modulus, Anisotropy, Tensile Testing, ISO 527