Assessing the Effect of Infill Percentage on Detectability of Defects Created in Polymer Parts Printed by the Fused Deposition Modeling (FDM) Using Sheared Laser Interferometry

This paper proposes a solution to the need for appropriate methods to control the health of the final product which is among the challenges of applying three-dimensional (3D) printers in mass production. Sheared laser interferometry so-called shearography is considered a proper option for this aim. The main objective of this paper is to inspect defective 3D-printed polymer parts. In addition, this study explores the influence of the infill percentage of the samples on the defect detectability as well as the shearography setup parameters. To this aim, three samples of Polylactic-acid (PLA) with different infill percentages were printed by the fused deposition modeling (FDM) method. Burnt filament defects were deliberately created inside the samples during printing. Shearography tests were carried out applying thermal excitation. Based on the results, the infill percentage directly affects the defect detectability as well as the shearography parameters. Accordingly, an increase in infill percentage enhanced the quality of shearography resultant fringe patterns. Additionally, it significantly leads to an increase in the detectable range of loading size and shear distance. Therefore, shearography was regarded as appropriate for detecting burnt filament defects, especially in high infill percentages.