The Temperature Compensation of FBG Sensor for Monitoring the Stress on Hole-Edge

Abstract

To apply Fiber Bragg Grating (FBG) sensors in the hole structural health monitoring of aircraft, this study investigates a temperature compensation algorithm based on Fourier curve-fitting, combined with an analysis of FBG layout. The results identify that the wavelengths have a linear relationship with stress and temperature and the linear correlation coefficients are all greater than 0.9. In the experiment, the temperature range was 17°C-100°C (step is 10°C) and the tensile force changed from 0 N to 10 KN (step is 1 KN). With the Fourier curve-fitting of the wavelength variation, the temperature compensation can be actualized, and the average error of temperature is 0.17°C. By integrating the algorithm in the self-developed FBG interrogation system, the real-time monitoring of stress is achieved with the average error of stress is 3.9 με.

An Optimized Self-Compensated Solution for Temperature and Strain Cross-Sensitivity in FBG Interrogators Based on Edge Filter

“…During each iteration of GWO, a simulation of the system's response for a strain-free condition with variable temperature is performed. The temperature (T) varies linearly from T min to T max in steps of δ T and, at each step, P is calculated by means of Equations ( 1), ( 5) and (11). Thus, the optical power curve versus temperature P(T) is obtained and the cost function (which GWO aims to minimize) is considered to be the difference between the maximum and minimum values of P norm (T) multiplied by its standard deviation σ (Equation (18)), where P norm (T) = P(T) − P(T = T min ).…”

“…Therefore, by tracking the Bragg wavelength of an FBG, strain and temperature may be estimated and exploited to provide several measurands such as humidity, pressure, magnetic field, vibration, acceleration, liquid level detection and concentration of a specific soluble [ 4 , 5 , 6 , 7 , 8 ]. For these reasons, FBG-based sensors have been an attractive alternative for sensing applications in various fields, e.g., structural health, chemical industry, aerospace, robotics and medicine [ 9 , 10 , 11 , 12 , 13 ].…”

The Analysis of FBG Central Wavelength Variation with Crack Propagation Based on a Self-Adaptive Multi-Peak Detection Algorithm

“…Therefore, this study mainly seeks to link the crack damage status directly to the damage features extracted from the reflection spectrum. In order to focus on the unique spectrum change variables that affect the stress/strain changes caused by the crack damage, then the effect of the other factors, such as the planar Bragg gratings [ 9 ], the cross-effect between temperature and strain [ 10 ] and curvature effects [ 11 ] have been taken into consideration by using healthy spectra which were acquired in a no crack state as the reference signals. Then the deformation spectrum can be compared with the basic signal to eliminate the impact of other factors.…”

Introductory Chapter: An Overview the Methodologies and Applications of Fiber Optic Sensing

“…A variety of linear and nonlinear optical transduction mechanisms have been studied in the last 30-40 years, dealing with the conversion from all kinds of measurands to local measurable optical effects in the fiber. There are previous works, for instance, that designed temperaturecompensated fiber Bragg grating (FBG) sensor for monitoring the stress [1], FBG-integrated spherical-shape structure for refractive index sensing [2], and D-shaped fiber combined with a FBG for refractive index and temperature sensing [3]. Fiber sensor can measure and/or monitor many parameters such as strain, weight, temperature, speed, pressure, and so on.…”