Distributed strain monitoring method for structural vibration based on multi-point acceleration measurement

Abstract

Fiber Bragg Grating (FBG) has been widely used in vibration monitoring due to its advantages of high sensitivity, resistance to electromagnetic interference and ease of networking. This paper proposes a method of distributed strain monitoring for vibrating structures where the surface is unsuitable for attaching FBG. This method utilizes measured multi-point acceleration to calculate dynamic displacement, and subsequently reconstructs distributed strain based on displacement matching and a displacement–strain function. Finite element simulation results demonstrate that the displacement matching scheme has higher strain reconstruction accuracy and broader adaptability. An FBG accelerometer with an equal-strength beam is designed, fabricated, and tested, exhibiting a resonant frequency of 56 Hz and an average sensitivity of 70 pm·g−1 in the flat frequency band. The proposed method is experimentally validated using a 12 m steel pipeline. It’s demonstrated that the displacement reconstruction error is less than 8 %, and the strain reconstruction error is less than 11 %.