Ultraviolet‐Assisted In Situ Shaping and Performance Evaluation of Continuous Carbon Fiber‐Reinforced Thermosetting Resin Matrix Composites in 3D Printing

ABSTRACT Continuous carbon fiber‐reinforced thermosetting composites (CCFRTS) are vital for aerospace thermal‐structural applications, such as solid rocket motor cases. 3D printing has emerged as a frontier for their material‐structure‐performance integrated manufacturing. However, online immersion 3D printing must balance low‐viscosity impregnation with rapid viscosity evolution for shape fidelity. This study proposes a UV‐assisted curing strategy using a photo‐thermal resin system, where reaction kinetics were investigated to precisely control the resin's rheological transition. By optimizing parameters like UV duration and printing parameters, a balance between impregnation and setting quality was achieved. The optimized components exhibited superior mechanical properties, with an interlayer shear strength (ILSS) of 32.3 MPa and impact strength of 57.47 kJ/m ² . This research provides a robust framework for the low‐cost, precision manufacturing of high‐performance composites, offering significant engineering value for aerospace pillar industries.