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International audienceThis paper describes a method to characterise the influence of in-plane shear on the permeability of fibrous preforms used in liquid composite moulding processes. An optical method for measuring the local shear variation of the woven textile is presented and used in conjunction with an in-plane permeability measurement system. Two flax fibre fabrics were tested and compared with a woven glass fibre fabric of similar architecture. The system presented here can be used either as a validation tool for permeability prediction models or to compile semi-empirical permeability models for the use in liquid composite moulding process simulation tools

Two experimental set-ups used to characterise the in-plane and through-thickness permeabilities of reinforcing textiles have been developed and are presented. Both the experimental testing and data processing techniques used have been selected to ensure that the characterisation is completed in an efficient and robust method, increasing the repeatability of tests while minimising user induced errors as well as the time and resources needed. A number of key results and outputs obtained are presented from tests carried out on a plain woven reinforcing textile with a range of number of layers and at different fibre volume fractions.

This paper compares the predicted permeability values obtained from conducting simulations with experimental results from the second permeability benchmark exercise. An automated tool, which has been developed for this purpose and is presented here, carries out flow simulations on WiseTex generated meshes using Ansys CFX. Different meshing methods are explored, and the effects of different boundary conditions, number of layers used to model the preform and the incorporation of nesting are examined. The predicted permeability values of the textile model closest to the real preform structure were higher by a factor of approximately two compared to the experimental values. In the second part of this work, the permeability values obtained using Ansys CFX and FlowTex solvers are compared and the ability of both solvers to capture variations in unit cell geometric parameters is demonstrated. A close agreement between the two solvers was found.

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