Comprehensively characterizing temperature overshoot of fast-curing resin by equilibrium heat transfer theory, in-situ monitoring and thermo-chemical coupled simulation

​Rapid composite molding offers cost effective route for high volume production, but fast-curing resins in thick-walled composites can trigger temperature overshoot, reducing product quality. This study integrated equilibrium heat transfer analysis, in-situ monitoring, and thermo-chemical coupled simulations to elucidate the mechanisms and size effects of overshoot for fast‑curing resins. Firstly, the curing mechanism was characterized by in‑situ hot‑stage FTIR to identify intrinsic triggers of temperature overshoot. Subsequently, the temperature overshoot phenomenon of a φ28H25(28mm in diameter and 25mm in height) resin block was monitored in situ with thermocouples, and equilibrium heat transfer analysis decoupled the temperature response into curing evolution and energy components. The decoupling results were validated using a high-precision thermos-chemical coupling model, with a temperature simulation accuracy deviation of 7.0%. Finally, correlation analysis was performed across resin blocks with diameters of 18/28 mm and heights of 25/50 mm, revealing overshoot temperatures of 67.5~153.6°C. The findings demonstrate that curing heat generation of the fast‑curing resin primarily controls overshoot magnitude, while geometric parameters modulate overshoot by altering autocatalytic behavior and energy transformation. The proposed decoupling methodology demonstrates the strong practical feasibility and clear mechanistic relevance, compared to high-precision simulation analysis, offering reliable and convenient guidance for manufacturing thick‑walled composites with fast‑curing resin systems.