High-precision continuous deformation monitoring method based on ultra-weak FBG array.

• This paper presents a cross-type fiber layout method. • This method can achieve deformation sensitivity of 1000 pm/mm. • This method can realize continuous small deformation monitoring of structures. Deformation monitoring is an important part of structural health monitoring. A high-precision continuous deformation monitoring method based on ultra-weak fiber Bragg grating (FBG) array sensing technology is proposed in this paper. The ultra-weak FBG array sensing fiber is continuously arranged by cross-type. The wavelength shift difference of the corresponding two ultra-weak FBGs is monitored in real-time to obtain the relative deformation between the monitoring nodes, so as to obtain the absolute deformation of all monitoring nodes. The mathematical model of continuous deformation based on cross-type is established and verified by experiments. The results show that this method has the advantages of good linearity, high-sensitivity, and temperature-insensitive. In the continuous deformation simulation experiment, the tiny deformation of the monitoring node is accurately obtained, and the error between the monitoring results and the actual deformation results is less than 5%. The proposed monitoring method is particularly suitable for continuous small deformation monitoring of large-scale metal structures. [ABSTRACT FROM AUTHOR]