Pseudo-unidirectional fiber networks are used in a variety of applications, such as woven fabrics and needling. A method for generating pseudo-unidirectional fiber networks by extruding linear portions of fibers is described here, and consists of two steps: Initially, a deliberately disorganized pseudo-unidirectional fiber network was generated geometrically from a stochastic algorithm according to the fiber volume ratio and the distribution law of the angles formed between the portions. Then, the fibers were flattened and mechanically deformed using a finite element calculation until restoring the pseudo-unidirectional fiber network geometry, having stored elastic energy. Mechanical inter-fiber contact interactions were finally activated in a relaxation step to obtain a disorganized network in mechanical equilibrium. Angular deviation and migration criteria were defined to geometrically characterize the network disorder before and after mechanical rearrangement, and were shown to correlate with the algorithm’s input parameters. Finally, the generated networks were mechanically characterized using a needle-punch, quantifying the transfer fraction. The mechanisms by which the needle carried and broke the fibers are discussed, and simulations demonstrate the influence of initial network disorder on fiber transfer. The particular case of needling involves transferring fibers present in a 2D web in its transverse direction in order to increase the out-of-plane stiffness of the final product. In this case, entanglement seemed to play a decisive role, as it favored fiber transfer.

中文翻译：

---

生成用于数值有限元模拟的缠结纤维网络的程序：在针刺情况中的应用


伪单向光纤网络有多种应用，例如机织织物和针刺。这里描述了一种通过挤压纤维线性部分来生成伪单向纤维网络的方法，该方法包括两个步骤：首先，根据纤维体积比和各部分之间形成的角度的分布规律。然后，使用有限元计算将纤维压平并机械变形，直到恢复伪单向纤维网络几何形状，并存储弹性能。纤维间的机械接触相互作用最终在松弛步骤中被激活，以获得处于机械平衡状态的无序网络。定义了角度偏差和迁移标准，以几何方式表征机械重排前后的网络紊乱，并显示与算法的输入参数相关。最后，使用针刺对生成的网络进行机械表征，量化转移分数。讨论了针携带和破坏纤维的机制，并通过模拟证明了初始网络紊乱对纤维转移的影响。针刺的特殊情况涉及沿横向转移二维纤维网中存在的纤维，以增加最终产品的面外刚度。在这种情况下，缠结似乎发挥了决定性作用，因为它有利于纤维转移。