Mechanical characterization of planar PLA/CF composites with cell-sized structures using fused filament fabrication

This study investigates the mechanical properties of various lattice patterns (circle, square, pentagonal, and hexagonal) and cell sizes (1 mm, 1.5 mm, and 2 mm) incorporated with polylactic acid/carbon fiber (PLA/CF) composites. Samples are fabricated using the fused filament fabrication technique, and the various mechanical properties such as tensile, compressive, flexural, and impact strengths are considered. The results show that the smallest cell size of 1 mm exhibits the highest mechanical properties across all the mechanical tests due to enhanced density and uniform stress distribution. Notably, the hexagonal lattice structure achieved maximum tensile strength (17.42 MPa) and compressive strength (46.14 MPa), attributed to efficient stress distribution and load-bearing capacity. Considering the energy absorption, hexagonal samples with a 1 mm cell size showed superior impact resistance, with an energy absorption rate of 85.75 J/m. A lower cell size of 1 mm can lead to issues such as voids and nozzle clogging. The hexagonal lattice structure, particularly at a 1.5 mm cell size (tensile, flexural, and compressive are above 75%, and energy absorption is cut to 50% than smaller cell size), provides a balance between printability and structural strength, making it a favorable choice for applications where mechanical strength and print quality are critical.