FDM process parameter optimization for mechanical performance of PLA/PLA-CF sandwich composites

The mechanical reliability of high-performance polymer composite materials can be enhanced by optimizing the process parameters of Fused Deposition Modelling (FDM). A new lightweight polylactic acid (PLA) and carbon fibre-reinforced PLA (PLA-CF) sandwich structure is studied and optimized under the Taguchi L9 orthogonal array design to achieve the best tensile behaviour. The maximum ultimate tensile strength (σ UTS ) of 47.9 MPa, Young’s modulus ( E ) of 1526 MPa and elongation at break (Ɛ f ) of 5.19% was achieved with the optimal parameter combination of concentric infill pattern (Level 1), 0.1 mm layer height (Level 1) and 150 mm/s printing speed (Level 1). The concentric infill gave the best structural reliability (peak S/N ratio of 33.57 dB) using the signal-to-noise (S/N) ratio analysis. Analysis of Variance (ANOVA) showed that the infill pattern was the most significant factor, accounting for 36.1% of the variation in load-bearing capacity and 34.2% of stiffness. The results of the confirmation test confirmed the Taguchi regression model (R 2 = 94.74%, p = .029) and showed that it significantly enhances the mechanical performance compared to the baseline configuration. The fractography performed by the Quantitative Scanning Electron Microscopy (SEM) showed that both the printing speed and the internal porosity were increased, however, the energy-dissipative mechanisms, such as fibre pull-out (23.8 ± 12.4 µm), contributed to the preservation of structural integrity. The results provide a scalable approach for the production of affordable and defect-tolerant multi-material FDM composites that can be used for automotive and aerospace applications.