Investigation and Assessment of Mechanical Properties of Co-extrusion with Towpreg Continuous Carbon Fiber Reinforced Thermoplastic Composites Manufactured using Material Extrusion

Additive manufacturing (AM) is an advanced technique to fabricate a complex geometrical structure using polymer, metals, ceramics, and composite materials. Fused filament fabrication (FFF) is the most widely used extrusion-based AM technique to manufacture polymer and composite parts. Continuous carbon fiber (CCF) is a lightweight high-strength material that offers exceptional mechanical durability and performance when incorporated with polymers; it significantly enhances their performance. To print continuous fibers using the material extrusion technique, various methods have been adapted according to the AM technology. In this study, a self-developed co-extrusion with towpreg method was employed to fabricate the continuous fiber polymer composites in which both the materials polymer filament matrix and CCF reinforcement were inserted separately and extruded together through a single nozzle. Two important printing process parameters (layer height and line width) were considered with different ranges to investigate their influence on the mechanical properties (tensile, flexural, shear and compressive), air void volume, and fiber volume fraction. The results obtained demonstrate that both parameters have a significant impact on the properties and are mostly influenced by the layer height of the samples. The group of composite specimens with the layer height of 0.4 mm and line width of 1.0 mm showed the highest tensile, flexural, shear, and compressive strength of 372.68, 247.59, 42.83, and 184.19 MPa, respectively, with the minimum air void volume of 13.84%. Furthermore, the research outcomes highlight that the composites properties can be optimized by adjusting printing process parameters. Highlights: Co-extrusion with towpreg process was employed to fabricate CCFRTC. Layer height and line width were investigated for their influence on properties. The theoretical model was used to predict modulus to validate the model's accuracy. The results demonstrated that both the parameters have a significant impact. This investigation led to improving the performance of CCFRTCs.