Parametric Optimization of the Mechanical Characteristics of 3D Printed Kevlar Fibre ‑PHA Composites using Taguchi’s Design of Experiments

The paper is a scientific exploration of the optimization of the mechanical characteristics of biodegradable polyhydroxyalkanoates (PHA) reinforced with Kevlar fiber (KF) fabricated through Fused Deposition Modeling (FDM). Composite filaments with different weight fractions of 0 wt.%, 10 wt.% and 20 wt.% Kevlar fiber were processed and printed at different printing speeds (40 mm/s, 60 mm/s, and 80 mm/s), infill densities (60%, 80% and 100%), and build orientations ( 0 ^o , 45 ^o and 90 ^o ). The Taguchi L27 orthogonal array was applied in order to optimize the process parameters in terms of tensile, flexural, and impact properties on the basis of the larger-is-better signal-to-noise (S/N) ratio criterion. The experimental data showed that the ultimate tensile strength was at its highest of about 104 MPa – 105 MPa, flexural strength of up to 97.7 MPa and impact energy of up to 2.25 J at the maximum infill density of 100% and 20 wt. % material content of Kevlar fibers. In case of tensile and flexural strength, the infill density was the most significant factor, and the delta value of the mean response analysis was highest, and Kevlar fiber content was the dominant factor in the optimization of impact strength. There were high synergies between the infill density and Kevlar fiber content as indicated by interaction plots. The similarity between the measured optimal conditions and the experimental ones proves the usefulness of Taguchi optimization in the improvement of the mechanical behavior of FDM-printed PHA–Kevlar fiber composites in terms of lightweight structural applications.