3D printing of continuous fiber-reinforced thermoset composites

Current printing methods for continuous fiber-reinforced composites require the composites to quickly solidify during the printing, so the matrix is limited to thermoplastics or thermosets with fast curing mechanisms. This paper presents the first design of a 3D printer head for direct-ink-writing that can overcome the limitations on printable resins. It leverages the shear stress imposed on the fiber to enable the ready extrusion of composite filaments and is applicable to a wide variety of thermoset resins and commercially-available continuous fibers. The developed printing method can create thermally-curable composite components with covalently bonded interfaces and comparable mechanical strength as directly-molded samples. It also enables the free-standing 3D printing of UV-curable composites. Overall, the developed printing method allows the composite parts to be designed quickly to meet unique specifications, as well as provides new functions in 4D printing, biomedical printing, and the printing of functional devices.