Consistent geometrical modelling of interlock fabrics

The aim of this study is to simulate the deformations of dry fabrics during the first step of LCM (Liquid Closed Moulding) processes. Among the available numerical approaches, 3D finite elements simulation at the mesoscopic scale seems to lead to a good compromise between realism and complexity. At this scale, the fibrous reinforcement is modeled by an interlacement of yarns assumed to be homogeneous that have to be accurately represented. The paper therefore presents the creation of a, as realistic as possible, 3D geometrical model of the yarns of complex unit cells. It is achieved through the implementation of an iterative strategy based on two main properties. On the one hand, consistency, which ensures a good description of the contact between the yarns, that is to say, the model does not contain spurious spaces or interpenetrations at the contact area. On the other hand, the variation of the yarn section shape along its trajectory is accounted so that it enables to stick as much as possible to the evolutive shape of the yarn inside the reinforcement. Using this tool and a woven architecture freely implementable by the user, a representative model of any type of reinforcement (2D, interlock) can be obtained. The obtained CAD model is fully consistent so that it can be directly used for FE simulations at the meso-scale without any modifications or corrections. An example of equi-biaxial extension of a carbon interlock fabric is proposed.