Permeability of sheared woven flax fibres reinforcements ; definition of parameters to model complex shape composites part processing by LCM

International audienceWith the increased use of Liquid Composite Moulding (LCM) processes in the aeronautical and automotive industries, the complexity of the parts and quality requirements have increased tremendously. The development of fabric forming models and the refinement of mould filling simulations, calls for improved material models to achieve the predictions expected by the industry. Accurate permeability data of reinforcing materials is essential in order to conduct LCM simulations and design the manufacturing process more efficiently [1]. Permeability is predominantly a function of the reinforcement architecture and its fibre volume fraction, both of which are affected by textile deformation when used to manufacture complex 3D parts. The push for more sustainable materials either biodegradable or fully recyclable has also pushed the composite industry to look increasingly at bio-based reinforcements and resins. The bio-based reinforcement being formed from the assembly of short fibrils of variable geometry into continuous strands have very different forming and permeability properties than traditional composite reinforcements formed by assembling continuous fibre with smooth geometry. This study compares the permeability characteristics of two different flax fibre fabrics with different tow size and a glass fibre fabric with an equivalent tow dimension. In order to gather information on the behaviour of such reinforcements during LCM manufacturing processes, the permeability behaviour of sheared textiles was determined. The fabrics were sheared before conducting the permeability tests, simulating the textile deformation that is present when preforming textiles in 3D moulds and the effects of these deformations on the textile properties were observed