Real-Time Monitoring of Strain Processes With Large-Range and High-Spatial Resolution Using the Method of Weak Reflection FBG Measurement Based on OFDR

The real-time monitoring of strain processes that can simultaneously realize a wide range and high spatial resolution has always been a huge challenge and cannot be satisfied by traditional electrical and noncontact measurement methods. In this article, the optical frequency domain reflection (OFDR) collocated with weak reflection fiber bragg grating (FBG) sensors (WRFBGs) was proposed to actively carry out multiple experiments on the nonstandard reinforcement samples with complex strain processes in order to overcome this challenge. According to the result analysis, the complex strain variation law of the surface of the sample and the large span strain of adjacent locations during the whole process of tensile can be obtained by this method. The yield point (YP) can be accurately captured and positioned with millimeter-level horizontal precision. At the same time, real-time monitoring can be realized for the step process, when the strain of the point increases to more than 25000-
$\mu \varepsilon $
instantly. The method can also realize the strain detection capability with a response speed of 38 Hz and a 1.28-mm high spatial resolution by monitoring the real-time high-density and large strain distribution.