Control of Thermal Gradients in Thin Resin Transfer Molding Parts

Resin transfer is a manufacturing process of composite materials where a thermodurcisable resin is injected in a closed mold containing dry fibrous reinforcement. After the entire mold has been filled, a curing reaction is initiated to bind the resin to the solid reinforcement. A rise in the mold temperature accompanies this exothermic curing reaction. The heat released gives rise to a temperature gradient in the composite. This thermal gradient causes residual stresses that are treated as undesirable since they cause deformations and affect the quality of the final product. In our numerical analysis by using the finite difference method for the composite laminate, we have first highlighted the thermal gradient by presenting the evolution of the temperature and the degree of cure during the resin curing; we then investigated the effect in the thermal gradient of the first the resin and fiber nature, second the reinforcement structure and last the temperature cycle choice. The validity of our model is evaluated by comparing numerical and experimental results in the existing literature, and a good agreement was observed.