Geometric modeling and recycling of 3D printed fiber reinforced thermoplastic composite plain weft knitted structures

Abstract In this paper, a novel geometric model of plain weft knitted structures, considering self-supporting conditions and process requirements is first proposed for 3D printed carbon fiber reinforced nylon composite, where the material extrusion additive manufacturing of a plain weft knitted structure is realized. Next, a recycling process of 3D printed carbon fiber reinforced nylon composite plain weft knitted structures is developed, to obtain recycled filament that can be directly used for 3D printing. The scanning electron microscope micrographs and the interfacial performance of the composite parts, manufactured from the original filament and the recycled one, were compared and analyzed. The results indicate that the performance of the recycled filament is continuously improving, because the recovery process enhances the infiltration of the nylon matrix into the surface of the carbon fiber. In the same printing condition, the tensile strength of composite printed with recycled filament is 56 MPa, which is improved by 16.7% compared to the composite printed using the original filament.