Fidan Bilir Kilinc

In this study, the effect of 3D printing process parameters, specifically line width and layer thickness, on the tensile properties of continuous carbon fiber-reinforced PLA composites fabricated via the Fused Filament Fabrication (FFF) method was investigated. The incorporation of continuous carbon fibers into the PLA matrix aims to enhance the mechanical performance of the printed composites, overcoming the inherent limitations of polymer-based additive manufacturing. The Taguchi method was employed to optimize the process parameters, enabling a systematic evaluation of their influence on tensile strength. An L9 orthogonal array was used to design the experiments, and the Signal-to-Noise (S/N) ratio was analyzed to determine the optimal parameter combination. The results demonstrate that line width and layer thickness significantly affect the tensile performance of printed composites, with narrower line widths (1.0 mm) and thinner layers (0.2 mm) yielding the highest tensile strength (291.3 MPa). Statistical analysis using Analysis of Variance (ANOVA) revealed that line width contributes 58.65% to the overall mechanical performance, making it the most influential factor, followed by layer thickness (33.55%). Microstructural analyses further confirmed that optimized printing parameters improve fiber alignment, enhance interlayer bonding, and minimize void formation. These findings highlight the crucial role of process optimization in maximizing the mechanical properties of FFF-printed continuous carbon fiber reinforced polymer (CFRP) composites, offering insights into achieving high-performance and lightweight structural components.

In this study, an aluminum heating block with two inlets (for the Polylactic acid (PLA) filament and the continuous aramid fiber) was produced and placed onto an extruder, and continuous-aramid-fiber-reinforced PLA composites were fabricated by using the nozzle impregnation method. Layer height values of 0.4 mm, 0.6 mm, and 0.8 mm and hatch spacing values of 0.6 mm, 0.8 mm, and 1.0 mm were used for the investigation of the processing parameters on the properties of composites by differentiating the reinforcement volume fraction. Additionally, atmospheric plasma treatment was used for the surface modification of the reinforcement fiber. The properties of composites reinforced by using surface-modified fibers were also investigated in order to reveal the efficacy of the atmospheric plasma treatment on the properties of composites. The effect of the atmospheric plasma treatment on the fiber properties was investigated by using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Continuous-aramid-fiber-reinforced PLA composites were characterized mechanically by fiber pull-out, tensile, and flexural testing. The fracture surfaces of composites were analyzed by using SEM. The combination of a reduced layer height and a narrower hatch spacing yielded the best mechanical performance, with a tensile strength of 410.25 MPa achieved at a 0.6 mm layer height and a 0.4 mm hatch spacing. This combination minimizes void formation, enhances fiber alignment, and strengthens interlayer adhesion, leading to superior mechanical properties. The FTIR and XPS results showed that atmospheric plasma modification can enhance the interfacial bonding strength by improving the surface morphology and increasing the content of polar groups on the fiber surface. By combining optimized manufacturing conditions with the atmospheric plasma treatment, the mechanical performance of continuous-aramid-fiber-reinforced PLA composites was enhanced.