Influence of infill density on microstructure and flexural behavior of 3D printed PLA thermoplastic parts processed by fusion deposition modeling

Abstract

The main goal of the present work was to investigate the influence of infill density (ID) on microstructure and flexural behavior of 3D printed parts by conducting three points bending test (3PBT). Flexural behavior of 3D printed parts is mainly dependent on ID which applied during printing. A thermoplastic of poly-lactic acid (PLA) was selected as material which can be best suitable for artificial tissue/bone engineering applications. Further, most of the artificial bones/tissues are subjected to fail due to bending load. Therefore, the effect of ID on the flexural strength of PLA (Bio-degradable) materials is important; which was addressed through this research work. Here, the PLA material was printed using fusion deposition modeling (FDM) by varying ID (40, 60, 80, and 100%). The 3D printed cylindrical specimen of 15 mm in diameter and 30 mm span was used. The bending responses in terms of bending stress-strain and bending force-deflection at each ID were investigated and reported. Furthermore, the fracture bending stress, fracture bending strain, flexural modulus, and stiffness of the printed sample were measured and correlated to the ID. The experimental result has shown that the bending characteristics influenced a strong correlation with ID percentage. The result suggested that the 80% ID was the optimum percentage which possessed considerable strength and toughness. Besides, the specimen surface morphology and the fracture topography were investigated and reported.