Laine, Bertrand (2008) Influence of fibrous reinforcement's deformations on its permeability : modelisations and experiments. PhD thesis Génie mécanique - procédés de fabrication, LAMCOS/ONERA-DMSC, ENSAM 2008ENAM0035 p.146.

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Abstract

The trend in the industry nowadays is to produce larger and larger as well as more

and more geometrically complex composite parts. Introduction of the resin in the fibrous

reinforcement by LCM (Liquid Composite Molding) techniques is increasingly used. The simulation

of this injection step is of prime importance in order to ensure the quality of the so-produced part.

To do so, it is necessary to take into account the influence of local deformations (shear,

compression and nesting) of the fibrous reinforcement on its permeability in the simulation. This

work presents experimental results on a new 2D setup which allows to perform measurements

using both air or silicone oil as permeation fluid. Results show very good correlation using these

two fluids. an inverse method has been used to determine the permeability of anisotropic media in

saturated regime. In parallel, a numerical tool has been developed in order to predict the influence

of each individual deformation on reinforcement permeability. Our tool uses 3D REV description

which is then deformed, meshed and finally the Stokes and Brinkman equations are solved in order

to determine the permeability by homogenization techniques. An analytical model based on

weaving parameters is proposed and shows very good correlation with 3D model. Influence of

shear, compression and nesting has been assessed for two woven fabrics as well as the influence

of the geometrical model used. These models allow to reduce the quantity of experiments needed

to fully characterize a fibrous reinforcement.

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