Novel application of dual-nozzle 3D printer for enhanced in-situ impregnation 3D printing of dry continuous fiber reinforced composites

This work reported a novel two-stage in-situ impregnation method for additively manufacturing dry fiber bundles reinforced polymer composites using a commercial dual-nozzle 3D printer. This process allowed simultaneous manufacturing of both continuous fiber prepreg filaments and continuous fiber reinforced polymer composites (CFRPCs). Initially, it was demonstrated that the two-stage in-situ impregnation method significantly enhanced the printing geometrical accuracy of specimens filled with rigid continuous carbon fiber. Subsequently, the tensile performance of CFRPCs, filled with twisted continuous ramie yarns and unwound continuous carbon fiber bundles, printed using single-stage and two-stage in-situ impregnations was compared. Significantly, the two-stage in-situ impregnation method facilitated a marked improvement in the tensile strength and modulus of CFRPCs. This improvement proved the enhanced impregnation effect of fibers, validating the effectiveness of the proposed two-stage in-situ impregnation approach for dry fiber bundles reinforced composites.