Factors Affecting the Interlayer Adhesion of Functionally Graded Materials Fabricated Using Fused Deposition Modeling

Functionally Graded Materials (FGMs) produced via Fused Deposition Modeling (FDM) present new opportunities for tailored structural components in aerospace and engineering applications. However, a key limitation in polymer–polymer FGMs remains the variability of interlayer adhesion, which significantly impacts mechanical performance under loading. This study investigates the influence of process parameters on the tensile behavior of dual-material FDM-printed FGMs constructed using Acrylonitrile Butadiene Styrene (ABS) and Tough Polylactic Acid (PLA). Although the original design targeted Polyether Ether Ketone (PEEK) for its superior thermal and mechanical properties, persistent processing constraints necessitated a material substitution with ABS—selected for its proven structural viability and compatibility with high-temperature FDM systems. A Taguchi Design of Experiments (DOE) framework was employed to evaluate the effects of nozzle temperature and raster angle on the ultimate tensile strength (UTS) of fabricated samples. Tensile testing was conducted in accordance with ASTM standards, and results were statistically analyzed to identify significant parameter interactions. Findings demonstrate that specific thermal and geometrical combinations yield notable improvements in tensile performance, underlining the critical role of process tuning in enhancing interfacial bonding. These insights contribute toward the development of mechanically reliable polymer-based FGMs and provide a basis for future optimization studies targeting functional grading in structural applications.