Virtual Description of Non-Crimp Fabrics at the Scale of Filaments Including Orientation Variability in the Fibrous Layers

A numerical description of dry non-crimp fabrics is proposed at the scale of the filaments using a commercially available finite element software package. Deviations in the filament orientation of the fibrous layer is a dominant factor in the occurrence of local defects, which influences the mechanical response of the textile. Therefore, the introduction of variability in the orientation distribution is proposed in this paper. This approach enables to capture the entanglement of the filaments and models all interaction mechanisms. A stepwise generation of the numerical non-crimp fabric is proposed considering the main manufacturing steps to reproduce the local defects in the fibrous mat appropriately. Averaged periodic boundary conditions are developed ensuring an overall periodicity of the model while allowing reorientation at the scale of the filaments. Two various non-crimp fabrics are investigated and modelled. The distribution of the filaments in the simulation results correlate well with measurements of the filament orientation performed on the textiles. Moreover, a detailed comparison of the local defects shows a good agreement with measurements on the specimens. The presented approach can be used to generate geometries for subsequent virtual characterization.