Abstract :
A control-volume finite-element model is developed to analyze the infiltration of a fiber preform with resin under nonisothermal
conditions within a high-permeability resin-distribution medium based vacuum-assisted resin transfer molding
(VARTM) process. Due to the exposure to high temperatures during preform infiltration, the resin first undergoes thermalthinning
which decreases its viscosity. Subsequently however, the resin begins to gel and its viscosity increases as the degree of
polymerization increases. Therefore, the analysis of preform infiltration with the resin entails the simultaneous solution of a
continuity equation, an energy conservation equation and an evolution equation for the degree of polymerization. The model is
applied to simulate the infiltration of a rectangular carbon fiber based preform with the NBV-800 epoxy resin and to optimize the
VARTMprocess with respect to minimizing the preform infiltration time. The results obtained suggest that by proper selection of
the ramp/hold thermal history of the tool plate, one can reduce the preform infiltration time relative to the room-temperature
infiltration time. This infiltration time reduction is the result of the thermal-thinning induced decrease in viscosity of the ungelled
resin.
