A Method of Structural Vibration Deformation Monitoring Based on FBG Strainmeter and Accelerometer Array

Abstract

The monitoring of displacement and strain distribution of vibrating structures is very important for maintaining structural safety. In this paper, a monitoring method of structural vibration deformation based on Fiber Bragg Grating (FBG) strainmeter array and accelerometer array is proposed for two different cases of whether the structure surface can be directly pasted with FBGs. In addition, a dynamic deformation estimation based on strain and acceleration data fusion, and a vibration morphology monitoring algorithm based on displacement reconstruction combined with finite element simulation results are proposed, respectively. An FBG accelerometer is designed based on an equal strength beam, for which the geometric parameters are determined by finite element simulation. The test results show that the accelerometer has a stable operating frequency band of 3-20Hz, an average sensitivity of 70pm/g, and a resonant frequency of 56Hz, which provides excellent linearity and consistency. The vibration deformation monitoring experiments were carried out on a cantilever aluminum plate. The results indicate that the measuring system is able to accurately sense the shape change of the structure in real-time with a displacement measurement error is < 6%. For the aluminum plate structure without FBG on the surface, the measuring system successfully reconstructed the displacement and strain distribution with a strain measurement error is < 10%.

Keywords

• Fiber Bragg gratings
• vibration monitoring
• dynamic deformation
• Kalman filter