The prediction of permeability for an epoxy/E‐glass composite using optical coherence tomographic images

Abstract

Knowledge of the permeability tensor in liquid composite molding is important for process optimization. Unfortunately, experimental determination of permeability is difficult and time consuming. Numerical calculation of permeability from a model reinforcement can circumvent experimentation. However, permeability predictions often rely on a model reinforcement that does not accurately mimic the actual microstructure. A rapid, nondestructive technique called optical coherence tomography (OCT) can image the microstructure of a composite in minutes. Actual microstructural information can be then used to improve the accuracy of the model and therefore the predicted permeability. Additionally, the influence on fiber volume fraction and microstructural variability on permeability can be systematically studied.In this work, binary images were generated from the low contrast OCT data through image de‐noising, contrast enhancement and feature recognition. The resulting data were input to a lattice‐Boltzmann model for permeability prediction. The influence of the fiber volume fraction, tow surface area, average mean free channel path, and variable microstructure are discussed in terms of their individual and synergistic effects on permeability. The calculated axial and transverse permeabilities from the images show very good agreement with the experimental values.

Analytic characterization of the permeability of dual-scale fibrous porous media

“…However, most experimental methods developed assume that the porous media is single scale [37][38][39][40][41][42]. The test fluid is either injected at a constant flow rate or under constant pressure and 1D line or 2D radial injection schemes are used.…”

Uncertainty in the manufacturing of fibrous thermosetting composites: A review

“…Several experimental and simulation studies have outlined the stochastic nature of permeability. Relative standard deviations up to 20% were observed during permeability measurements [14,26,27,[31][32][33][34][35][36], while according to other results permeability relative standard deviation can reach values up to 30% [13] ( Table 1). The high scatter observed in [13] is probably due to the small number of experiments compared to the other studies.…”

“…Compressibility studies have clearly indicated that irrespective of fabric type, for a given pressure, the thickness per layer decreases due to nesting [30][31][32][33][34][35]. However, in the results presented in [36], the thickness per layer increased with increasing the number of lamina layers, as a result of friction between the layers which prevented the occurrence nesting.…”

Estimation of a stochastic spatio-temporal model of the flow-front dynamics with varying parameters

“…Estimating a good model for the change in viscosity of the epoxy during the infusion process is not trivial. Similarly estimation of the permeability model through numerical simulation or experimental characterization of the permeability is a cumbersome task [3,4]. Previously, we used the partial differential equations (PDE) (derived using the Darcy's law) based flow-front model for our simulation study [5] and proposed a parsimonious grey-box model of the flow-front dynamics using coupled SDEs [6].…”