Structural Design of Vat‐Photopolymerized Continuous Fiber Composites via a Split Matrix Prefabrication–Post Fiber Infiltration Route

Traditional fiber‐reinforced polymer (FRP) manufacturing suffers from limited geometric freedom, protracted fabrication cycles, and inconsistent mechanical performance across finished components. Here we report a decoupled vat photopolymerization workflow combining photocurable resin matrix preprinting and post‐filling of continuous carbon/glass fibers, with E51 epoxy deployed as an interfacial binder. We systematically quantify how fiber type, carbon fiber loading, internal channel architecture, and carbon/glass hybrid fiber layout govern composite flexural performance via three‐point bending assays, multi‐scale interfacial characterization, and Abaqus finite‐element modeling. Carbon fiber reinforcement delivers the largest gains in flexural strength and stiffness: failure load and elastic modulus rise by 154.1% and 105.1% relative to neat resin, while glass fibers dominate energy dissipation and toughening. Flexural performance scales monotonically with carbon fiber content. Axially aligned full‐end‐hole channel structures exhibit 208.3% higher integrated flexural performance than transverse full‐side‐hole architectures. This framework delivers quantitative design guidelines for high‐performance vat‐photopolymerized FRPs targeting lightweight advanced manufacturing applications.