Evaluation and prediction of tensile properties of 3D-printed continuous carbon/Kevlar fiber-filled composites by coaxial hybrid process

Continuous hybrid fiber-reinforced composites (CHFRCs) have excellent mechanical properties, and strong designability, and are widely used in aerospace and other fields. The development of 3D printing technology offers novel directions in the design and manufacture of complicated CHFRC components in aerospace. For this purpose, this study focused on the design and characterization of hybrid continuous fiber-reinforced composites prepared by 3D printing. The rapid mold-free integrated manufacturing of hybrid continuous Kevlar/carbon fiber-reinforced composites was realized by coaxial hybrid 3D printing technology. The regulation and mechanism of tensile properties of 3D-printed CHFRCs were elucidated. The tensile strengths of 3D-printed CHFRCs were enhanced by up to 15.3% and 92.4%, respectively, compared to single continuous carbon and Kevlar fiber composites produced by the same process parameter. A new tensile modulus predicting method for 3D-printed CHFRCs was proposed. It mitigated the influence of complex interfacial characteristics on mechanical property prediction and achieved precise estimation of the tensile modulus of 3D-printed CHFRCs. This will provide the theoretical support for the application and development of 3D-printed CHFRCs. Highlights: Mouldless rapid manufacturing of coaxial hybrid fiber composites achieved. The tensile strength and modulus of the fiber composites are greatly improved. A new prediction method for the tensile modulus of 3D-printed composites is proposed.