MECHANICAL CHARACTERIZATION OF POLYLACTIC ACID WITH DIFFERENT INFILL PATTERNS AND ARRANGEMENTS USING FUSED DEPOSITION MODELING

Abstract

Infill patterns significantly affect the mechanical properties, printing time and material consumption of 3-Dimensional (3D) printed Polylactic Acid (PLA) parts. Despite the wide variety of available infill patterns, the effect of combining and arranging multiple infill patterns on strength-to-weight ratio within a single print remains underexplored. This study investigates the effect of infill pattern arrangements on enhancing the strength-to-weight performance for applications requiring strong yet lightweight components. Three infill patterns (Lines, Triangles and Gyroid) were selected and arranged in three different configurations: by-layer, by-horizontal area and by-vertical area. By-layer arrangement exhibited improved tensile strength, Young’s Modulus and strength-to-weight ratio. BL5 with 50% infill density and arranged by-layer, demonstrated the best performance, with a tensile strength of 17.77 MPa and strength-to-weight ratios of 2.85 MPa/g. The infill patterns in this arrangement, delays crack propagation, as the non-continuous geometry created by the varied patterns disrupts the crack path. In contrast, the lowest tensile strength was observed for by-vertical area arrangement, where the tension load was applied perpendicular to the interface between different infill patterns, increasing the likelihood for crack initiation and propagation. Although the by-layer arrangement required a longer printing time, it produced part with a superior strength-to-weight ratio compared to the other arrangements, making it an effective strategy for balancing mechanical strength and material efficiency.