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.

使用市售的有限元软件包，可以在长丝规模上对干燥的非卷曲织物进行数值描述。纤维层的长丝取向的偏差是发生局部缺陷的主要因素，这会影响织物的机械响应。因此，本文提出了在方向分布中引入可变性的方法。这种方法能够捕获细丝的缠结并模拟所有相互作用机制。考虑到主要制造步骤以适当地再现纤维垫中的局部缺陷，提出了一种逐步产生数字无卷曲织物的提议。开发了平均的周期性边界条件，以确保模型的整体周期性，同时允许在细丝的尺度上重新定向。对两种不同的非卷曲织物进行了研究和建模。在模拟结果中，长丝的分布与在纺织品上执行的长丝取向的测量值非常相关。此外，对局部缺陷的详细比较表明与样品的测量结果吻合良好。所提出的方法可以用于生成用于后续虚拟表征的几何形状。局部缺陷的详细比较显示与样品的测量结果吻合良好。所提出的方法可以用于生成用于后续虚拟表征的几何形状。局部缺陷的详细比较显示与样品的测量结果吻合良好。所提出的方法可以用于生成用于后续虚拟表征的几何形状。