Formability of curved multilayer laminates via 3D printing using twisted continuous fiber composites

3D printers can print free-form 3D shapes; however, their mechanical properties are unsatisfactory. 3D printers can print 3D shapes freely but the resulting products exhibit unsatisfactory mechanical properties. 3D printing using CFRTP enables the formation of 3D structures with improved mechanical properties. When molding a structure with curved parts using a continuous carbon-fiber-reinforced thermoplastic (CFRTP) 3D printer, the difference in the inner and outer paths of the filament width during arc printing causes the CFRTP filament to become twisted, resulting in poor molding accuracy. In this study, we evaluated the formability of laminates via 3D printing with twisted CFRTP filaments to reduce the inner and outer path differences. And the maximum change in the filament width, which is defined as the maximum width minus the minimum width in one round of fibers, was defined as the forming accuracy. In the case of single-layer printing, the filament width decreased as the twist angle increased, and the forming accuracy (variation in the filament width) decreased. However, when stacking multiple layers, the maximum change in the filament width was the least when the twist angle was 6°. The discovery of the optimum twist angle at 1 K is the most significant aspect of this study and indicates the possibility of an optimum twist angle for various values of K.