Effect of Perturbation of Fibre Architecture on Permeability Inside Fibre Tows

The influence on the permeability inside fibre tows from fibre packing arrangement and non-uniform fibre diameter is investigated. The analysis mainly consider flow transverse to the fibres and is based on the fibre geometry. Perturbations from perfect quadratic and hexagonal arrangements of fibres at constant fibre volume fraction are considered. The importance of microgeometry on permeability is pointed out and it is indicated how to deal with this problem. The analysis shows that the fibre transverse permeability is strongly dependent on the fibre size distribution. When an arrangement of equally sized fibres is continuously changed from quadratic to hexagonal it is furthermore found that the transverse permeability is highest just before the packing gets hexagonal. The analysis is also applied to a simple FORTRAN code to simulate removal of fibers from a quadratic arrangement. The simulations shows that the transverse permeability decreases with increased number of removed fibres under constant fibre ...