Influence of Textile Parameters on the Out-of-Plane Permeability of Carbon Fiber Non-Crimp Fabrics

Abstract

Within the last years, liquid composite molding (LCM) is gaining more and more importance for the automotive industry due to weight saving of (semi-)structural car parts. In order to make carbon fibre parts economically more interesting for this area, short cycle times are necessary. Hence, one concept is the impregnation of carbon fibre parts in through-the-thickness direction. The behaviour of the impregnability depends mainly on the out-of-plane permeability of the fabric. The permeability of the fabric is mainly influenced by the fibre type, orientation of the fibres, and the stitching parameters. In this study the influence of textile parameters on the out-of-plane permeability of 45° and 0°/90° biaxial carbon fibre non-crimp fabrics (NCF) was investigated. The stitching yarn parameters (linear mass density and stitch length) were varied to see the influence on the out-of-plane permeability. The out-of-plane permeability was measured using a measurement cell based on flow front monitoring with ultrasonic technology at a minimum of three different fibre volume contents between 47 % and 63 % to show the decrease of permeability with respect to the fibre volume content. The results show that the out-of-plane permeability of the 0°/90° carbon fibre NCF are not significantly affected by the yarn linear mass density and the stitch length. Conversely the 45° carbon fibre NCF is affected by the stitch length, but not by the yarn linear mass density.