模型相似材料内部应变光纤量测应变传递

Strain transfer of internal strain of model similar materials with optical fibre measurement

应用光纤传感技术测量模型相似材料内部应变,必须解决光纤与相似材料耦合的问题。传统的研究中普遍存在应变传递理论分析结果无法通过试验检验的问题。设计实现了一种基于光纤-胶体-相似材料3层应变传递结构的光纤Bragg光栅(FBG)相似材料一维传感器。通过对该传感器应变传递特性和标定方法的研究探索解决光纤与相似材料耦合性的问题。该传感器采用无涂覆层的光纤Bragg光栅作为传感元件,将光纤埋入相似材料应变试件内部直接测量轴向中心应变。通过应变传递理论分析、数值模拟以及全新设计的标定试验研究3种方法研究了该相似材料光栅传感器的应变传递特性。平均应变传递率结果显示3种方法所得到的数值非常接近,表明该传感器的光纤、胶体、相似材料具有良好的耦合性以及应变测量的准确性。该方法为解决模型相似材料内部三维应变测量提供了可行方案。

The optical fibre sensing technology has been widely used to measure the internal strain of similar material. However, the coupling between the optical fibre and similar materials has not yet been resolved. In previous studies, theoretical results of strain transfer cannot be validated in the experiments. A one-dimensional optical fibre Bragg grating （FBG） similar material was designed and realized using three layers of fibre-adhesive-similar material. The sensor provides a method to solve the problem of coupling between the fibre and similar material. The FGB sensor without coating layer was used as the sensing element, and the axial centre strain was measured by using the fibre embedded in the similar-material strain testing pieces. We investigated the behaviour of strain transfer using theoretical analysis, numerical simulation and a newly designed calibration. The results of the average strain transfer rate of the sensor obtained by different methods were very close, which demonstrated good coupling among fibre, adhesive and similar material. Moreover, the accuracy and reliability of theoretical analysis and numerical simulation were verified by a new calibration experiment. The method provides a feasible solution for the three-dimensional strain measurement of similar material in the model.