Reconstruction of structural damage based on reflection intensity spectra of fiber Bragg gratings

Huang, Guojun; Wei, Changben; Chen, Shiyuan; Yang, Guowei

doi:10.1088/0957-0233/25/12/125109

Cited by 7 publications

(6 citation statements)

References 31 publications

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“…Before the fatigue testing, the reflection intensity spectra of the FBG sensors under free loading state are measured as a reference. These spectra are used for the inversion of the property parameters of FBG sensors based on the T-matrix method [17]. Properties of FBG sensors are listed in Table 3.…”

Section: Methodology Validationmentioning

confidence: 99%

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Probabilistic Model Updating for Sizing of Hole-Edge Crack Using Fiber Bragg Grating Sensors and the High-Order Extended Finite Element Method

Yang

Wang

et al. 2016

Sensors

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This paper presents a novel framework for probabilistic crack size quantification using fiber Bragg grating (FBG) sensors. The key idea is to use a high-order extended finite element method (XFEM) together with a transfer (T)-matrix method to analyze the reflection intensity spectra of FBG sensors, for various crack sizes. Compared with the standard FEM, the XFEM offers two superior capabilities: (i) a more accurate representation of fields in the vicinity of the crack tip singularity and (ii) alleviation of the need for costly re-meshing as the crack size changes. Apart from the classical four-term asymptotic enrichment functions in XFEM, we also propose to incorporate higher-order functions, aiming to further improve the accuracy of strain fields upon which the reflection intensity spectra are based. The wavelength of the reflection intensity spectra is extracted as a damage sensitive quantity, and a baseline model with five parameters is established to quantify its correlation with the crack size. In order to test the feasibility of the predictive model, we design FBG sensor-based experiments to detect fatigue crack growth in structures. Furthermore, a Bayesian method is proposed to update the parameters of the baseline model using only a few available experimental data points (wavelength versus crack size) measured by one of the FBG sensors and an optical microscope, respectively. Given the remaining data points of wavelengths, even measured by FBG sensors at different positions, the updated model is shown to give crack size predictions that match well with the experimental observations.

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Section: Methodology Validationmentioning

confidence: 99%

“…The transfer matrix method (T-matrix) was firstly introduced by Leblanc [16] to simulate the reflection intensity spectrum of FBG according to the strain profile along the grating. Huang [17] developed an optimization approach for crack damage reconstruction based on the simulated reflection intensity spectrum through the T-matrix method.…”

Section: Introductionmentioning

confidence: 99%

Probabilistic Model Updating for Sizing of Hole-Edge Crack Using Fiber Bragg Grating Sensors and the High-Order Extended Finite Element Method

Yang

Wang

et al. 2016

Sensors

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“…The sensing elements of the smart Geogrid in this study are fiber Bragg grating (FBG), which are formed by inscribing a permanent and periodic modulation of the refractive index along a short section inside the fiber optic core [27][28]. According to Bragg's law, the Bragg wavelength shift Δλ changes linearly with the axial strain of the fiber optic ε, as expressed in equation ( 1) as follows:…”

Section: Strain Sensing Principle Of the Smart Geogridmentioning

confidence: 99%

Deformation reconstruction of a smart Geogrid embedded with fiber Bragg grating sensors

Wang

Sui

et al. 2015

Meas. Sci. Technol.

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Due to the disadvantages of the current smart Geogrid for geotechnical use only being able measure strain and evaluate load location, a smart Geogrid embedded with fiber Bragg grating (FBG) sensors has been developed. Also, a deformation reconstruction technique has been investigated, which enables the newly designed smart Geogrid to evaluate the deformation fields of the key areas in geotechnical structures. After the fabricating process of the FBG embedded smart Geogrid was briefly introduced, a curvature information based deformation reconstruction method for the smart Geogrid was detailed. In order to optimize the distribution of the FBG nodes in the smart Geogrid, the finite element (FE) simulation data of the three possible causes of deformation were extracted, and the reconstruction results of the four distributions were compared. The results indicated that equidistantly distributed FBG sensors at the ribs of the smart Geogrid were the optimal distribution for the newly designed smart Geogrid. In addition, a modified deformation reconstruction technique was proposed to reduce reconstruction errors due to the stress concentration on the junctions of the smart Geogrid. The modified method, which employs FBG measured strains for calculating the deformation of the ribs and weighted strains to compute the coordinates of the two junctions, was validated by FE simulations. The simulation results illustrated that the modified method can improve the deformation reconstruction accuracy for both a Geogrid embedded with one fiber optic cable into one warp thread and a Geogrid embedded with multiple fiber optic cables in different warp threads. For the purpose of verifying the feasibility of the deformation measurements for the designed smart Geogrid using the proposed reconstruction techniques, experiments for the smart Geogrid embedded with one fiber optic cable were conducted in constant temperature environments. The curvatures of the smart Geogrid were calibrated prior to the deformation experiments in order to remove the errors induced by the strain measurement. The experimental results demonstrated that the reconstruction technique for the newly designed smart Geogrid was capable of evaluating the deformation field, and the modified reconstruction technique was able to effectively improve the reconstruction accuracy in order to fulfill the requirements of geotechnical usages. The newly developed smart Geogrid with deformation reconstruction techniques can be a promising smart Geosynthetic for the reinforcement as well as the monitoring of geotechnical engineering-related applications.

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“…With the aid of the FBG sensing technology, a growing number of investigators have paid attentions to structural safety assessment of in-service bridges [ 21 , 22 , 23 , 24 , 25 , 26 ]. Also, investigations have been carried out on monitoring of dynamic responses and damage of structures based on FBG sensors [ 27 , 28 , 29 , 30 ].…”

Section: Introductionmentioning

confidence: 99%

Statistical Analysis of Stress Signals from Bridge Monitoring by FBG System

2018

Sensors

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In this paper, a fiber Bragg grating (FBG)-based stress monitoring system instrumented on an orthotropic steel deck arch bridge is demonstrated. The FBG sensors are installed at two types of critical fatigue-prone welded joints to measure the strain and temperature signals. A total of 64 FBG sensors are deployed around the rib-to-deck and rib-to-diagram areas at the mid-span and quarter-span of the investigated orthotropic steel bridge. The local stress behaviors caused by the highway loading and temperature effect during the construction and operation periods are presented with the aid of a wavelet multi-resolution analysis approach. In addition, the multi-modal characteristic of the rainflow counted stress spectrum is modeled by the method of finite mixture distribution together with a genetic algorithm (GA)-based parameter estimation approach. The optimal probability distribution of the stress spectrum is determined by use of Bayesian information criterion (BIC). Furthermore, the hot spot stress of the welded joint is calculated by an extrapolation method recommended in the specification of International Institute of Welding (IIW). The stochastic characteristic of stress concentration factor (SCF) of the concerned welded joint is addressed. The proposed FBG-based stress monitoring system and probabilistic stress evaluation methods can provide an effective tool for structural monitoring and condition assessment of orthotropic steel bridges.

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Reconstruction of structural damage based on reflection intensity spectra of fiber Bragg gratings

Cited by 7 publications

References 31 publications

Probabilistic Model Updating for Sizing of Hole-Edge Crack Using Fiber Bragg Grating Sensors and the High-Order Extended Finite Element Method

Probabilistic Model Updating for Sizing of Hole-Edge Crack Using Fiber Bragg Grating Sensors and the High-Order Extended Finite Element Method

Deformation reconstruction of a smart Geogrid embedded with fiber Bragg grating sensors

Statistical Analysis of Stress Signals from Bridge Monitoring by FBG System

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