Mesoscopic finite element modeling of biaxial non-crimp fabric including representative stitch pattern

A comprehensive understanding of the mechanical properties of carbon fiber reinforcements is necessary to accurately simulate forming processes. The parametrization of macroscopic models requires extensive experimental characterization for different deformation modes. In order to reduce experimental effort, this work proposes a mesoscopic model of bi-axial non-crimp fabric (Bi-NCF) that can be used for virtual material characterization. The fiber yarns are considered as a continuous medium and modeled with solid elements, and their mechanical behavior is described by a hyperelastic constitutive law dedicated to anisotropic fibrous media. The stitches are modeled with 2-node beam elements. This model is developed based on precise geometry measurements obtained from X-ray tomography results. An additional stitch pre-tension step is incorporated in the model to improve contact and simulate the tension induced by the sewing process. Experimental Picture Frame Tests are used to validate the model at mesoscale, while experimental and numerical Bias-extension Tests demonstrate its potential to simulate larger scales and effectively predict local defects.