Modelling variation of textile fabric permeability at mesoscopic scale

Textile permeability in general shows a high variance. The present work describes a method to model textile variability at the mesoscopic scale based on a generalised textile model. Inhomogeneities were introduced into the textile structure by randomly moving the tow paths at the cross-overs according to a given normal distribution. The effects of various factors on the evaluated permeability variation were explored and demonstrated, using non-crimp fabric and plain weave models. Fabric architecture was shown to be important in that it imposed a limit to the degree of variation of the tows. A linear relationship can be deduced for the relative variation of permeability as a function of the relative variation of fibre volume fraction, which links the predicted and measured values. When utilising predicted mesoscopic permeability values in macroscopic analyses, the domain size of the mesoscale model has to be related to the element size of the macroscopic analyses.