Zhou Chunhua, Chen Changhao, Ye Zilong, Wu Qi, Xiong Ke
State Key Laboratory of Mechanics and Control for Aerospace Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
Shanghai Institute of Satellite Engineering, China Aerospace Science and Technology Corporation, Shanghai 201109, China.
Sensors (Basel). 2024 Sep 24;24(19):6190. doi: 10.3390/s24196190.
Embedded fiber Bragg gratings are increasingly applied for in-situ strain measurement in fiber-reinforced plastics, integral to high-end aerospace equipment. Existing research primarily focuses on in-plane strain measurement, limited by the fact that fiber Bragg gratings are mainly sensitive to axial strain. However, out-of-plane strain measurement is equally important for comprehending structural deformation. The birefringence of fiber Bragg gratings shows promise for addressing this problem; yet, the strain transfer relationship between composites and optical fibers, along with the decoupling method for multi-directional strains, remains inadequately explored. This study introduces an innovative method for multi-directional strain measurement in fiber-reinforced plastics using the birefringence of a single-fiber Bragg grating. The strain transfer relationship between composites and embedded optical fibers was derived based on Kollar's analytical model, leading to the development of a multi-directional strain decoupling methodology. This method was experimentally validated on carbon fiber/polyetherimide laminates under thermo-mechanical loading. Its reliability was confirmed by comparing experimental results and finite element simulations. These findings significantly broaden the application scenarios of fiber Bragg gratings, advancing the in-situ measurement technology crucial for the next generation of high-end aerospace equipment.
嵌入式光纤布拉格光栅越来越多地应用于纤维增强塑料的原位应变测量，这对于高端航空航天设备至关重要。现有研究主要集中在平面内应变测量，因为光纤布拉格光栅主要对轴向应变敏感，这限制了其应用。然而，平面外应变测量对于理解结构变形同样重要。光纤布拉格光栅的双折射有望解决这一问题；然而，复合材料与光纤之间的应变传递关系以及多方向应变的解耦方法仍未得到充分探索。本研究介绍了一种利用单光纤布拉格光栅双折射进行纤维增强塑料多方向应变测量的创新方法。基于科拉尔的分析模型推导了复合材料与嵌入式光纤之间的应变传递关系，从而开发了一种多方向应变解耦方法。该方法在热机械载荷下的碳纤维/聚醚酰亚胺层压板上进行了实验验证。通过比较实验结果和有限元模拟，证实了其可靠性。这些发现显著拓宽了光纤布拉格光栅的应用场景，推动了对下一代高端航空航天设备至关重要的原位测量技术的发展。
