Out-of-plane permeability of 3D woven fabrics for composite structures

Polymer composites in structural applications commonly provide reinforcement based on 2D textile products, such as woven fabrics or non-crimp fabrics. This leads to sensitivity for delamination and high lay-up effort, especially when a large part thickness is required. 3D woven fabrics (3D-WF) can prevent delamination by incorporating fibers in out-of-plane direction and given the increased areal weight of the single layers, the effort for lay-up is strongly reduced. However, large part thicknesses are also challenging when it comes to impregnation. A high out-of-plane permeability helps facing this challenge. Within this study, the saturated out-of-plane permeability of different 3D-WF (glass fiber) with an areal weight ranging from 1850 g/m(2) to 5242 g/m(2) was measured. It was found that at an equal fiber volume content of 50% the increase of out-of-plane oriented reinforcement fibers leads to an increasing out-of-plane permeability with increasing areal weight.