Investigating the Influence of Strain Rate on Tensile, Flexural, and ILSS of Fused Deposition Modeling Printed PLA Polymer

This study aims to investigate the effect of varying strain rates on the mechanical strength of neat polylactic acid (PLA), focusing on the influence of different strain rates on the material’s failure mechanisms. By examining these variations, this research seeks to optimize the mechanical properties of fusion deposition modeling (FDM) printed PLA, addressing the inherent weaknesses in interlayer bonding. PLA samples were printed with a grid infill pattern at 75% infill density, a 0.16 mm layer height, and a ± 45° printing orientation. Tensile, flexural, and interlaminar shear tests were performed at strain rates ranging from 6 to 10 mm/min according to ASTM standards. The highest tensile strength recorded was 38.89 MPa at a cross-head speed of 8 mm/min, with the highest elongation reaching 4.8%, interlaminar shear strength (ILSS) of 76.49 MPa at 9 mm/min, and the maximum flexural strength of 70 MPa at 6 mm/min. At a cross-head speed of 8 mm/min, the highest tensile strength measured was 38.89 MPa, while the elongation measured was 3.8%, the flexural strength measured was 65 MPa, and the interlaminar shear strength was 76.04 MPa, which is very close to the highest recorded value. It can be suggested that a strain rate of 8 mm/min is optimal for testing FDM printed PLA, as it yields balanced and high-performance results across tensile, elongation, flexural, and interlaminar shear properties. This strain rate (8 mm/min) could be effective for analyzing failure mechanisms and material behavior under mechanical loading. This study could be helpful for the researchers working in the area of 3D-printed polymers, in understanding the behaviors of the materials with respect to varying strain rates.