3D Printing of Continuous-Fiber-Reinforced Composites: Advances in Multifunctional Integration and Intelligent...

Extrusion-based additive manufacturing has emerged as a transformative route for 3D-printed continuous-fiber-reinforced polymer composites (3DP-CFRPCs), offering unprecedented opportunities to engineer lightweight structures with programmable mechanical and multifunctional properties. However, existing studies largely treat constituent materials, printing processes, structural design, and functional integration as isolated research topics, limiting the development of robust design principles for intelligent composite systems. This review proposes an architecture-centric smart architecture framework that extends conventional material-process-structure-property relationships by explicitly incorporating reinforcement-path architecture, interface/defect evolution, multifunctional states, and cyber-physical feedback as coupled design and state variables. Within this framework, we critically synthesize the coupled roles of matrix rheology, fiber impregnation, interfacial bonding, and fiber trajectory engineering in determining printability, defect evolution, and mechanical performance. Recent advances in co-extrusion technologies, multi-axis printing, topology optimization, and programmable fiber placement are further discussed as enabling strategies for architected composite design. Particular emphasis is placed on defect-controlled reliability, multifunctional integration, and emerging AI-enabled digital twins that facilitate closed-loop process optimization and intelligent manufacturing. Finally, the remaining challenges regarding scalability, repeatability, and intelligent composite architectures are outlined to accelerate the transition from laboratory-scale demonstrations to industrial deployment.