The permeability of tackified, stitched, and braided carbon fiber textiles: Experimental characterization and design modeling

Liquid composite molding (LCM) has greatly benefited from advances in textile preforming. Large and complex part-shapes can be assembled and held in place until resin injection and curing. The three most common preform stabilization techniques are tackification (binders), stitching, and braiding. The often complex geometrical arrangement and inhomogeneous and anisotropic nature of these textile preforms has complicated attempts to model the processing and final properties of such materials, thus hindering their applicability. This paper focuses on the experimental characterization of the permeability of advanced carbon fiber textile preforms. Permeability knowledge allows the simulation of resin flow during processing in LCM. The inplane permeability is determined by the multiple cavity parallel flow technique. Non-crimped fabric (NCF) with various configurations and binder amounts, tailored fiber-placement (TFP) stitched fabric in a variety of orientations, and both biax and triax braided samples are characterized. Previous literature includes measurements of glass-fiber based preforms, and simple carbon weaves and NCF's. But no permeability data has been published for these particular state-of-the-art materials. Strategies to model the design of a preform using similar materials are also presented.