The effect of infill type ratio on strength of PLA and ABS thermoplastics

This study investigates the effect of honeycomb infill density on the tensile strength of 3D-printed specimens fabricated using Fused Deposition Modeling (FDM) technology with PLA (Polylactic Acid) and ABS (Acrylonitrile Butadiene Styrene) thermoplastics. The motivation for this work stems from the increasing demand for lightweight polymer components in engineering applications, where reliable tensile performance is critical for structural safety. Although honeycomb structures are traditionally preferred for compression-dominated applications such as heels, heat exchangers, and lightweight cores, they are also increasingly employed in tensile load-bearing components such as lightweight brackets, connecting links, prosthetic parts, and aerospace/automotive fixtures. Understanding their tensile properties is therefore essential for effective design. Specimens with infill densities ranging from 15 % to 100 % were modeled in CATIA V5 and analyzed in ANSYS R21 using a honeycomb (hexagonal) pattern. Tensile strength was evaluated for each density and compared against ASTM E8 tensile properties of plastics. Results show that PLA specimens achieved a maximum tensile strength of 60.02 MPa at 100 % infill, while ABS specimens reached 52.54 MPa. Strength improvement from 15 % to 100 % infill was approximately 60–70 %. PLA exhibited superior stiffness and strength, making it suitable for tensile applications, whereas ABS showed higher strain and deformability. The findings confirm that infill density is a key parameter influencing the tensile performance of thermoplastic parts produced by FDM.