Liu Xiao, Tang Zuoyin, Gui Xin, Yin Wenchang, Cao Jingyi, Fang Zhigang, Li Zhengying
School of Information Engineering, Wuhan University of Technology, Wuhan 430070, China.
School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China.
Sensors (Basel). 2024 Nov 29;24(23):7637. doi: 10.3390/s24237637.
Monitoring of real-time flow and defects in the vacuum-assisted resin infusion (VARI) process can provide important guidelines for full impregnation of dry reinforcement. A weak fiber Bragg grating array was employed to obtain quasi-distributed monitoring results in real-time. Sensitivity testing of different kinds of coated optical fiber sensors (OFs) was carried out first, and the polyacrylate-coated OF showed a greater wavelength-shift response than the polyimide-coated one. Then, two- and three-dimensional flow monitoring tests were carried out. During the resin-filling stage, three trends of strain curve were identpified in relation to the different placement setups of embedded OFs, the resin flow direction, and the different vacuum-bagging methods. The monitoring criteria were analyzed and the results were compared with the visual inspection, showing good agreement and indicating the ability of the fiber Bragg grating array. Finally, defects including dry spots and voids were introduced and reflected in the maximum changed strains of FBGs due to the smaller stress relaxation, indicating the potential to characterize the local flow state and permeabilities experimentally based on these quasi-distributed sensing methods.
监测真空辅助树脂灌注（VARI）过程中的实时流动和缺陷可为干增强材料的完全浸渍提供重要指导。采用弱光纤布拉格光栅阵列实时获取准分布式监测结果。首先对不同类型的涂覆光纤传感器（OFs）进行了灵敏度测试，结果表明，聚丙烯酸酯涂覆的OF比聚酰亚胺涂覆的OF表现出更大的波长位移响应。然后，进行了二维和三维流动监测测试。在树脂填充阶段，根据嵌入式OF的不同布置方式、树脂流动方向和不同的真空袋封装方法，确定了应变曲线的三种趋势。分析了监测标准，并将结果与目视检查进行了比较，结果显示出良好的一致性，表明了光纤布拉格光栅阵列的能力。最后，引入了包括干点和孔隙在内的缺陷，由于较小的应力松弛，这些缺陷反映在FBG的最大应变变化中，这表明基于这些准分布式传感方法通过实验表征局部流动状态和渗透率的潜力。
