Modeling Flow‐Deformation Coupling to Predict Fiber Deformation During the Continuous Lamination of Organosheets

ABSTRACT Predicting the flow‐induced fiber deformation that limits the double‐belt press (DBP) lamination of organosheets is critical for manufacturing high‐performance composites. This work develops a dual‐mechanism squeeze flow model that explicitly couples macroscopic squeeze flow with mesoscopic resin percolation, and an associated predictive framework, including a power‐law criterion for instability initiation and a dimensionless Instability Index, to quantify the resulting fiber deformation. The developed squeeze flow model is validated against laboratory‐scale experiments, and the Instability Index shows a strong positive correlation (, ) with measured fiber deformation in industrial‐scale trials covering temperatures of 230°C–270°C, belt speeds of 2–6 mm/s and roller gaps of 2.0–2.4 mm. Furthermore, the influence of DBP process parameters, such as temperature, belt speed, and roll gap, on the mechanical properties of the final organosheets is analyzed, associating the observed non‐monotonic trends with the fiber instability predicted by the framework. This validated framework provides a quantitative and practical tool for DBP process optimization, offering physical insight into process dependent instability and enabling high precision forming process simulation and performance control.