Reinforcing in the lay-up direction with self-heating for carbon fiber composites fabricated using a fused filament fabrication 3D printer

Abstract In recent times, 3D printers have been employed to fabricate continuous fiber composites. The 3D-printed composites fabricated via fused filament fabrication have no reinforcing fibers in the lay-up direction, resulting in low stiffness and strength in this direction. In the present study, a simple method to reinforce the lay-up direction of 3D-printed composites is proposed. First, a composite part with a through rectangular hole is fabricated via 3D printing. A rectangular reinforcing bar with continuous carbon fibers is then printed separately. Subsequently, the reinforcing bar is inserted into the through hole. A large electric current is applied to the carbon fibers in the reinforcing bar, and the surface thermoplastic polymer is melted via resistive heating (self-heating). As a result, the bar becomes fused to the part, which increases the stiffness and strength of the part. Tensile test and bending test specimens in the lay-up direction were fabricated using commercially available 3D printers. The results show that the simple reinforcing method effectively improves the mechanical properties of the part in the lay-up direction.