Mechanism characterization and multiphysics predictive modeling of photo-thermal coupled curing in GFRP

Photocuring is widely used in composite manufacturing for its efficiency, yet ultraviolet light attenuates inside fiber-reinforced composites due to fiber occlusion and scattering, limiting cure depth and causing local defects. To address this, we propose a light-initiated photo-thermal coupled curing approach. Combining differential scanning calorimetr, dielectric analysis, and in-situ optical monitoring with a multiscale representative volume element framework, we systematically characterize key parameters and their evolution in glass-fiber-reinforced polymer during photo-thermal coupled curing, and accordingly construct and validate an accurate finite-element multiphysics model. Based on the photo-thermal coupling mechanism, the curing process is decoupled into photopolymerization and thermal-curing subprocesses modeled separately, with bidirectional feedback achieved via dynamic linkage of key parameters. The model reliably predicts the spatiotemporal evolution of the light field, temperature field, and degree-of-cure field. Experiments and simulations jointly show that thermal curing significantly compensates shadowed regions, effectively expanding the manufacturable thickness window. This study provides a quantitative basis for process design of thick and highly opaque composite laminates.