Abstract A 3D numerical model is established to characterize the fibrous network materials and the fracture behavior is investigated through the finite element method (FEM) analysis. The numerical results show that fibrous network material is insensitive to the crack when the crack length is less than a critical value, which is three times as much as the average length of fiber segments in the fibrous network. In addition, the toughening mechanism of the fibrous network material is revealed based on the FEM simulations. Due to the damage accumulation of bonds near the crack tip, the fibers around the crack tip are reoriented and become perpendicular to the crack path, which can further inhibit the crack propagation, and the deformation mode changes from bending-dominated deformation to tensile-dominated deformation, with the loading capacity of the fibrous network materials enhanced. The results in this paper demonstrate that the fibrous network materials show damage-tolerance to the small crack under the critical crack length, and the fibrous network formed by brittle fibers can exhibit ductile behaviors by controlling the microstructure and relative density, which is useful for the design and optimization of fibrous network materials.

中文翻译：

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纤维网络材料的断裂行为：裂纹不敏感性和增韧机制

摘要 建立了表征纤维网络材料的3D数值模型，并通过有限元法(FEM)分析研究了断裂行为。数值结果表明，当裂纹长度小于临界值时，纤维网络材料对裂纹不敏感，该临界值是纤维网络中纤维段平均长度的三倍。此外，基于有限元模拟揭示了纤维网络材料的增韧机制。由于裂纹尖端附近键的损伤积累，裂纹尖端周围的纤维重新定向并垂直于裂纹路径，可以进一步抑制裂纹扩展，变形模式由弯曲主导变形转变为拉伸主导变形。形变，随着纤维网络材料的负载能力增强。本文的研究结果表明，纤维网络材料对临界裂纹长度下的小裂纹具有损伤耐受性，脆性纤维形成的纤维网络可以通过控制微观结构和相对密度来表现出延展行为，这有助于纤维网络材料的设计和优化。