The influence of fabrics’ design parameters on the 3D permeability tensor of quasi-unidirectional non-crimp fabrics.

Abstract : This study addresses the effects of quasi-UD non-crimp fabric (NCF) design parameters on the permeability tensor. These fabrics are designed for the Liquid Resin Infusion (LRI) of large and thick composite parts. Three fabrics parameters intended to bring a flow enhancement to the NCF are investigated: the stitch spacing, the stitch pattern and the weft tow linear mass density. A modified continuous permeability measurement method based on compressive tests is undertaken to relate the 3D permeability of the quasi-UD NCF to the design parameters during the infusion process. The measurement bench has been modified so as extract in-plane permeability and through-thickness coefficients. The fabrics design parameters are proven to influence significantly both the fibrous morphology and therefore the permeability tensor.