Print Process Optimization and Viscoelastic Characterization of Vat‐Photopolymerized Glass Fiber‐Reinforced Composites via Experimental and Predictive Modeling

ABSTRACT This study presents a novel approach to fabricating high‐performance photopolymer composites (PPCs) using digital light processing (DLP)‐based vat photopolymerization with precision placement of continuous woven E‐glass fabrics. Unlike previous studies that relied on random or low‐volume reinforcements, this work introduces a layer wise geometric correlation method that enables the incorporation of up to four fabric layers (18.7%–69.9% fiber volume fraction) without significant dimensional distortion. A three‐stage build‐platform optimization strategy was developed to eliminate interlayer gaps, enhance resin infiltration, and improve interfacial bonding, resulting in superior dimensional fidelity. Dynamic mechanical analysis showed that the 0/90° composite with 69.9% fiber volume fraction achieved the highest storage modulus of 3600 MPa and a glass transition temperature of 65°C. To capture the viscoelastic behavior over a wide range of temperatures and time scales, a modified Halpin‐Tsai model combined with Williams‐Landel‐Ferry (WLF) shift factor analysis was proposed and validated, revealing an activation energy of 376.3 kJ/mol and long relaxation times at low frequencies. The integration of high fiber fractions, novel placement methodology, and predictive modeling demonstrates a significant advancement in the fabrication of durable, thermally stable composites for long‐term structural applications.