Multi-Objective Optimization of FDM Infill Patterns Using Design of Experiments Considering Load-Path Alignment

Fused Deposition Modelling (FDM) is widely employed in additive manufacturing (AM) of polymer components, where process parameters play a critical role in determining mechanical performance and resource efficiency. Although process parameters, such as layer height, build orientation and infill density, have been extensively studied with respect to tensile strength, the combined influence of infill pattern, density, and skin layer configuration remains insufficiently explored. In this research, six infill patterns, namely concentric, line, triangle, honeycomb, grid, and gyroid, are evaluated at three density levels (50%, 75%, and 90%) with multiple skin layer configurations using an L36 orthogonal experimental design. Tensile tests are analyzed using analysis of variance (ANOVA) to identify the significant factors and their interactions, supported by pattern-specific interaction plots. The results indicate that tensile strength increases by increasing infill density in a similar pattern; however, when comparing different patterns, the concentric infill consistently exhibits superior tensile strength along with reduced printing time, material consumption, and energy usage. This behavior can be primarily explained by the filament alignment parallel to the applied tensile load, which promotes load transfer through continuous material paths rather than interlayer bonding with implications for effective build orientation selection through controlled filament alignment. Overall, the findings demonstrate that concentric infill provides an effective strategy for optimizing the tensile strength while minimizing the environmental impact, offering practical guidance for sustainable FDM part design.