Effect of build parameters and strain rate on mechanical properties of 3D printed PLA using DIC and desirability function analysis

• Published in: Rapid prototyping journal 2023-01, Vol.29 (1), p.92-111
• Main Authors: Ali, Shafahat, Abdallah, Said, Devjani, Deepak H., John, Joel S., Samad, Wael A., Pervaiz, Salman
• Format: Article
• Language: English
• Subjects: 3-D printers; CAD; Computer aided design; Crack propagation; Deformation; Density; Digital imaging; Ductility; Fractures; Function analysis; Impact strength; Mechanical properties; Polylactic acid; Process parameters; Rapid prototyping; Strain rate; Taguchi methods; Tensile strength; Three dimensional printing; Yield stress
• ISSN: 1355-2546; 1758-7670; 1355-2546
• DOI: 10.1108/RPJ-11-2021-0301

Purpose This paper aims to investigate the effects of build parameters and strain rate on the mechanical properties of three-dimensional (3D) printed polylactic acid (PLA) by integrating digital image correlation and desirability function analysis. The build parameters included in this paper are the infill density, build orientation and layer height. These findings provide a framework for systematic mechanical characterization of 3D-printed PLA and potential ways of choosing process parameters to maximize performance for a given design. Design/methodology/approach The Taguchi method was used to shortlist a set of 18 different combinations of build parameters and testing conditions. Accordingly, 18 specimens were 3D printed using those combinations and put through a series of uniaxial tensions tests with digital image correlation. The mechanical properties deduced for all 18 tests were then used in a desirability function analysis where the mechanical properties were optimized to determine the ideal combination of build parameters and strain rate loading conditions. Findings By comparing the tensile mechanical experimental properties results between Taguchi's recommended parameters and the optimal parameter found from the response table of means, the composite desirability had increased by 2.08%. The tensile mechanical properties of the PLA specimens gradually decrease with an increase in the layer height, while they increase with increasing the infill densities. On the other hand, the mechanical properties have been affected by the build orientation and the strain rate in similar increasing/decreasing trends. Additionally, the obtained optimized results suggest that changing the infill density has a notable impact on the overall result, with a contribution of 48.61%. DIC patterns on the upright samples revealed bimodal strain patterns rendering them more susceptible to failures because of printing imperfections. Originality/value These findings provide a framework for systematic mechanical characterization of 3D-printed PLA and potential ways of choosing process parameters to maximize performance for a given design.