Estimation of local permeability/porosity ratio in resin transfer molding

Resin transfer molding (RTM) is a promising technique for manufacturing fiber-reinforced plastic (FRP) composites. In RTM, the permeability/porosity ratio of the preform is a critical process parameter, which varies with the geometric formation of the fiber reinforcement. This parameter dominates the characteristics of resin flow and influences the final product quality. Most of the existing measurement methods treat the material porosity as a constant and estimate the permeability of the entire fiber preform as a single value, while local variations are ignored. In this study, a measurement system is developed to estimate the local values of the permeability/porosity ratio, which does not require mounting pressure sensors in the mold. Instead, at each sampling time point, the overall (global) permeability/porosity ratio of the fiber preform between the injection gate and the flow front is calculated. Then, the local ratio is derived based on the relationship between the overall and local values. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.