In-plane permeability characterization using an inverse method based on flow front visualization

Abstract

In this study, we propose a method to reduce the total number of required one-dimensional resin flow experiments for in-plane permeability (K) characterization of isotropic fabrics by achieving either: (i) a characterization and further statistical analysis of spatially varying permeability in the presence of fabric irregularity and possible race-tracking along the fabric - mold wall interface, or (ii) permeability characterization at more than a single fiber volume fraction (vf) in an experiment. The method is based on accurately detecting the flow front location in the flow propagation video frames and minimizing the deviation between experimental fill times and numerical fill times in Control Volume Finite Element based flow simulations through use of the Levenberg-Marquardt method. The permeability of an isotropic random mat was characterized through reference experiments. K-vf relationship was well represented by a power law. In cases with intentionally introduced race-tracking and with three sections of different vf, permeability results were in agreement with the results of the reference experiments (a set of experiments in which fabric irregularity and race-tracking were eliminated as much as possible). The results indicate that the number of experiments, thus the material and time invested, can be significantly reduced using the proposed method with an additional benefit of obtaining valuable insights on the statistics of the spatial permeability distribution.