The Enhanced Measurement Method Based on Fiber Bragg Grating Sensor for Structural Health Monitoring.

The effective measurement method plays a vital role in the structural health monitoring (SHM) field, which provides accurate and real-time information concerning structural conditions and performance. The innovative measurement approach based on strain sensors, referred to as the inverse finite element method (iFEM), has been considered the most promising and versatile technology for meeting the requirements of the SHM system. However, the existing iFEM for shape sensing of thick plate structures has the drawback that the transverse shear effect makes no contribution to the three-dimensional deformation of thick plate structures. Therefore, this study proposed an enhanced inverse finite element method (iFEM) based on single-surface fiber Bragg grating strain sensors for reconstructing thick plate structures coupled with an analytical formulation. The method characterized the explicit relationship between transverse shear and bending displacement field on the mid-plane, which presents the sixth-order differential equation based on a variational approach. The three-dimensional deformation field can be obtained along the thickness direction, expanding the SHM application of iFEM for composite structures based on strain measurement. By performing shape sensing analysis of the thick plate model, the exactness and applicability of the present method are numerically and experimentally validated for different loading cases.