Research on strain field detection system for complex surface based on FBG

In order to collect the real-time strain distribution of complex surface shapes, and provide data support for the health assessment of complex surface structures, the strain field detection system for complex surface was designed with fiber-optic sensor network. The system consisted of a fiber laser, a coupler, a demodulator, and a fiber sensing array. The method was compared with the optical scanning detection data, and the theoretical analysis and simulation calculation of the strain distribution were carried out under many different conditions. The strain distribution of the device under test with a variety of different force conditions was simulated and analyzed. The results show that the strain distribution is related to the applied position, size and surface structure. A 5.0mm aluminum plate was tested and compared with simulation data in the experiment. Four groups of fiber grating sensors were placed on the surface to be measured in an orthogonal structure arrangement. The test results show that the maximum wavelength offsets are 1.324nm, 2.547nm, and 1.643nm, and the corresponding shift offsets are 0.244mm, 0.523mm, and 0.347mm, respectively. Compared with the calibration data of laser scanning method, the offset of this method is relatively less than 10%. The test data can reflect the trend of surface shape change, and it meets the design requirements.