Finite element model for NCF composite reinforcement preforming: Importance of inter-ply sliding

A semi-discrete model is proposed for the simulation of non-crimp fabric reinforcement preforming. This approach is based on experimental observations of in-plane shear deformations of the reinforcement, out-of-plane bending and inter-ply sliding during the non-crimp fabric preforming. The experiment highlights strong sliding between the two plies of the non-crimp fabric during forming. The two plies of fibers composing the reinforcement are modeled by two layers of shell elements; the stitches are modeled by bar elements. The relationship between bar and shell elements is managed with a specific contact and anisotropic friction law associated to sliding threshold. This meso-macroscopic approach allows the simulation of industrial part forming in a reasonable computational time. The model shows a good prediction of deformations during the forming on a hemispherical shape. In particular sliding between the two fiber layers of the NCF obtained by the simulation is in good agreement with that measured during the preforming experiment.