A finite element simulation approach to the mechanical behaviour of 3D angle-interlock fabrics at the scale of their internal components, using an implicit scheme, is presented in this paper. Based on the determination of the static equilibrium of assemblies of fibres, this approach is used first to find the unknown initial configuration of a unit cell of angle-interlock fabric, by implementing an original method to gradually separate initially inter-penetrating yarns. This method, only based on the weaving pattern, does not require any geometrical pre-processor. Various loading cases can then be simulated to characterize the non-linear behaviour of such fabrics. Applications to the determination of the initial configuration of the unit cell of a typical example of a 5-layer angle-interlock fabric, and to the simulation of a transverse compression test and a forming test are presented.

Friction between single fibres or between tows is an important element in the mechanical properties of composite reinforcement. Therefore, knowledge of the friction behaviour at the two scales, tow and fibre, is necessary for a deep understanding of the mechanical behaviour of composite reinforcement. In the models, the strategy used is to consider a constant coefficient of friction. This paper presents an efficient method of measuring the coefficient of friction relative to an inter-tow or inter-fibre sliding angle of 0° to 90°. The results show that the coefficient of friction decreases when the angle increases. Moreover, the friction is very high when the fibres are parallel. This result is explained by the increase of the adhesion between fibres at the interface of the tows due to a large total contact area at 0°, as proved by an analysis performed based on Hertz's contact theory.

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