Abstract
A novel fiber Bragg grating (FBG)-based strain sensor with a high-sensitivity is presented in this paper. The proposed FBG-based strain sensor enhances sensitivity by pasting the FBG on a substrate with a lever structure. This typical mechanical configuration mechanically amplifies the strain of the FBG to enhance overall sensitivity. As this mechanical configuration has a high stiffness, the proposed sensor can achieve a high resonant frequency and a wide dynamic working range. The sensing principle is presented, and the corresponding theoretical model is derived and validated. Experimental results demonstrate that the developed FBG-based strain sensor achieves an enhanced strain sensitivity of 6.2 pm/με, which is consistent with the theoretical analysis result. The strain sensitivity of the developed sensor is 5.2 times of the strain sensitivity of a bare fiber Bragg grating strain sensor. The dynamic characteristics of this sensor are investigated through the finite element method (FEM) and experimental tests. The developed sensor exhibits an excellent strain-sensitivity-enhancing property in a wide frequency range. The proposed high-sensitivity FBG-based strain sensor can be used for small-amplitude micro-strain measurement in harsh industrial environments.
Highlights
The strain is one of the most important monitored physical parameters in the structural health monitoring (SHM) of modern mechanical equipment [1,2,3]
The measured signals from traditional electrical strain sensors are contaminated by electromagnetic interference (EMI) in a harsh industrial environment, which deteriorates the performance of an SHM system [4]
This paper presents a sensitivity-enhanced Fiber Bragg grating (FBG) strain sensor based on a substrate with a lever structure
Summary
The strain is one of the most important monitored physical parameters in the structural health monitoring (SHM) of modern mechanical equipment [1,2,3]. SHM requires a high strain sensitivity to the applied strain sensors. The experimental results showed that this sensor’s sensitivity could reach 3.357 pm/με These sensors can achieve a higher strain sensitivity compared with directly-pasted bare FBG sensors. They are fragile and easy to be broken due to the thin flexure hinges. The working frequency bandwidth of the sensor is not wide enough for high-frequency dynamic strain measurements in mechanical equipment. This paper presents a sensitivity-enhanced FBG strain sensor based on a substrate with a lever structure. The designed sensor has the advantages of a simple and compact structure, high strain sensitivity in a wide frequency range, convenient installation, and high consistency and reliability. The developed sensor can assist in small-amplitude micro-strain measurements in a harsh industrial environment
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