Verification of a Simulation Model for Resin Film Infusion of Complex Shaped Composite Structures

Abstract

Resin film infusion (RFI) has been found to be a cost-effective technique for the fabrication of complex shaped composite parts for primary structural applications. Dry textile preforms are infiltrated, consolidated, and cured in a single step, eliminating the labor to lay-up prepreg tape. The large number of processing variables and the complex material behavior during infiltration and cure make experimental optimization of the RFI process extremely inefficient. The objective of this work was to develop and verify a three-dimensional model to simulate the RFI process. For a specified pressure and temperature cure cycle the code can predict resin pressure, viscosity and degree of cure, flow front progression, and temperature distribution in the preform and tooling components. The model was divided into submodels which describe resin flow, heat transfer, and resin kinetics. A finite element/control volume approach was used to model the flow of the resin through the preform. Boundary conditions include specified pressure, specified flow rate, and vents. A finite element formulation of the transient heat conduction equation was used to model the heat transfer. Thermal boundary conditions include either specified temperature or convection. The code was designed to be modular so the flow problem could be solved alone, or coupled with the thermal problem. The problems are solved sequentially in a quasi-steady state fashion. Non-isothermal experiments with a reactive resin were conducted to verify the thermal module and the resin model. A two blade stiffened panel, fitted with sensors, was manufactured using the RFI process. Thermocouples were used to measure the temperatures, and FDEM (dielectric) sensors and pressure transducers were used to monitor the flow front progression. Model predictions and experimental results were found to be in close agreement for the temperatures and flow front progression. The predicted and measured infiltration times matched to within 12%, and the temperatures to within 5%.