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This study analyses the influence of the random filament arrangement in fibre bundles on the resin flow behaviour. Transverse steady-state resin flow that occurs behind a liquid resin flow front was simulated numerically through statistically equivalent micro-structures at high-fibre volume fractions, V f > 0.6, as observed in fibre bundles. The need of applying a minimum gap distance between neighbouring filaments was overcome by automated local mesh refinement. The derived permeability values showed significant scatter. Convergence of these values was determined at a ratio of flow length to filament radius greater than 20 for all three analysed fibre volume fractions. Mean permeabilities were between 6 and 10 times lower than those predicted for a hexagonal fibre array. A statistical model is proposed, which is able to predict the scatter of observed permeabilities based on simple micro-structural descriptors.

An efficient method to describe and quantify the filament arrangement in fibre bundles based on the analysis of micrographs was developed. Quantitative measurement of relative filament positions indicated that the initially random arrangement of filaments shows increasingly strong characteristics of square and hexagonal configurations with increasing level of transverse compaction. An existing micro-structure generator was extended to incorporate the measured data allowing statistically equivalent filament arrangements to be generated at any fibre volume fraction. These can be used to determine micro-structural properties of actual fibre reinforced composites.