Abstract: Glass fiber reinforced composites (GFRC) are a popular, low-cost, and lightweight structural material widely used in green energy fields, such as wind power generation, new energy vehicles, and battery shells. However, delamination damage is a common issue in GFRC structures during service. To improve the out-of-plane mechanical properties of laminated GFRC, various interlaminar materials have been extensively studied and applied. To prevent sudden delamination of GFRC during service, it is crucial to develop an in-situ, real-time, on-line non-destructive monitoring method to monitor the structural health of the system. This will help avoid catastrophic failure caused by sudden delamination. A PET-CNT self-sensing nonwoven composite interleaf was developed by using high-porosity PET nonwoven fabric, introducing functional intercalation into the interlayer relative to GFRC for modification. In addition, the one-step impregnation method produced a PET-CNT nonwoven interleaf with a multi-level network structure of entangling, loose and porous, allowing full impregnation with resin matrix. Upon solidification, a continuous and dense CNT-CNT seepage induction network was formed. The results demonstrated an 86% increase in initial fracture toughness (GIC,ini) and a 48% increase in propagation fracture toughness (GIC,prop) of the modified GFRC, effectively enhancing its mode I interlaminar fracture toughness (ILFT). Real-time acquisition of piezoresistive response and establishment of quantitative mapping relationship between resistance change and crack growth length revealed a 270% gain factor in resistance change rate during the experiment, demonstrating excellent in-situ monitoring sensitivity and accurate efficiency in monitoring the entire process of crack growth in DCB experiment.
In this study, a new PET-CNT nonwoven composite interleaf suitable for GFRC was prepared, and its integrated response behavior of interlayer toughening-structure monitoring was analyzed and verified, which proposed an effective and structural optimization method to improve the structural stability of GFRC and the overall robustness of GFRC throughout its life cycle. Additionally, it also provided a new scenario for expanding the industrial application of functional nonwoven materials.

Key words: nonwoven fiber web, self-sensing composites, glass fiber reinforced composites, interleaving toughening, toughening-monitoring integrated response, structural health monitoring

摘要： 为了避免玻璃纤维增强复合材料（GFRC）在服役过程中由于局部分层损伤造成灾难性整体失效，采用高孔隙率、薄型聚对苯二甲酸乙二醇酯（PET）非织造纤网构筑PET-碳纳米管（CNT）自感应复合纤网插层，将其嵌入玻纤增强体层间一体成型，在改善GFRC层间性能的同时，对其结构健康状态进行原位、实时、在线的无损监测。结果表明：PET-CNT复合纤网改性GFRC的起始断裂韧性和扩展断裂韧性分别提高了86%和48%，有效提升了GFRC的I型层间断裂韧性。另外，在裂纹扩展阶段，PET-CNT复合纤网插层的电阻变化率增益因子高达270%，表现出了极高的层间裂纹监测敏感性。文章为提升GFRC面外力学性能并实现SHM提供了一种集成结构增韧-监测功能一体化的新型非织造复合纤网插层，也为提升GFRC全寿命周期稳健性提供了一种结构优化方法。

关键词: 非织造纤网, 自感应复合材料, 玻璃纤维增强复合材料, 插层增韧, 增韧-监测一体化响应, 结构健康监测