Novel 3D printed continuous fiber-reinforced composites: A strategy to realize spiral mode manipulating and support-free manufacturing

Abstract

To meet the demands of lightweight, high-strength, and multifunctionality in advanced systems, a manufacturing strategy based on helical-gradient continuous-fibers for both reinforcement and sensing is needed. We developed an integrated fabrication platform that combined a resin-coated continuous-fiber twisting extrusion process with 3D printing. This platform enables unsupported 3D printing for fabricating helical-fiber-reinforced composite specimens exhibiting multiple helical modes and graded twist levels. Compared with conventional non-twisted-fiber composites, the resulting filaments exhibited superior mechanical properties—with tensile and flexural moduli increased by 172 % and 202 %, respectively—and displayed a pronounced change in resistance under strain. Quantitative models were established that relate helical architectures to mechanical and sensing responses. We designed several sensing devices based on these composites, including a resistive strain sensor, a dual-helical resistive sensor, and a capacitance–resistance hybrid sensor. Notably, the resistive strain sensor achieved a 562 % increase in sensitivity relative to conventional materials, while the capacitance-resistance hybrid sensor simultaneously detected distance, angle, and pressing positions using two sensing interfaces for large-area applications. This study provides innovative technological support for multifunctional, high-efficient industrial applications in aerospace, automotive, health monitoring, and related fields.