Investigation on Characteristic Variation of the FBG Spectrum with Crack Propagation in Aluminum Plate Structures

Jin, Bo; Zhang, Weifang; Ren, Feifei; Dai, Wei; Wang, Yanrong

doi:10.3390/ma10060588

Cited by 9 publications

(13 citation statements)

References 17 publications

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“…Meanwhile, the subordinate peaks vary with the complex strain distribution along the grating. In addition, the relationship between the subordinate peak and the strain distribution pattern has been discussed and simulated in previous research [13]. The turning subordination peaks coincide with the crack length, which is represented in the comparison between Figures 5(a) and 6(a) with Figure 7(a).…”

Section: Resultsmentioning

confidence: 99%

“…As the FWHM of reflection spectra increases, reflectance decreases and the subordinate peaks appear initially, and even spectra distortion occurs. Reference [13] investigates the subordinate peak located in the lower wavelength, with quadratic strain distribution being employed along the grating of the fiber. When the cubic strain gradient is employed along the grating of the fiber, the subordinate peak is located at a higher wavelength.…”

Section: Mechanism Of the Skewing Of The Subordinate Wavelengthmentioning

confidence: 99%

“…Peters et al [12] discussed the spectra of the FBG as a possible basis for the resolution of an arbitrary applied strain distribution. Jin et al [13] discussed the subordinate peak of the reflection spectrum in crack propagation monitoring of aluminum alloys. The FBG was placed parallel to the external loading direction.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of Subordinate Peak Skewing of FBG Sensor during Cracks Propagation Monitoring on Aluminum Alloy Structure

et al. 2017

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This study investigates the variety of the spectra features of fiber Bragg grating (FBG) around the crack tip during fatigue crack propagation. The study results reveal that the turning of the subordinate peak is significantly associated with crack lengths and corresponds to strain gradient along the FBG. Meanwhile, the strain distribution sensed by the FBG changes with the sensing section of the grating. FBG sensors could observe the monotonic plastic zone ahead of the fatigue crack tip. The cubic strain is distributed along the grating, with monotonic plastic zone propagation at the initial and terminal part of the grating, at approximately a 30% ratio of the entire grating. However, the monotonic plastic zone is sensed by the FBG, at ±15% bias of the grating center, with the quadratic strain gradient pattern along the grating. In particular, when the initial and terminal parts of the grating experience highly inhomogeneous strain distribution, the spectrum distortion occurs.

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Section: Resultsmentioning

confidence: 99%

Section: Mechanism Of the Skewing Of The Subordinate Wavelengthmentioning

confidence: 99%

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Mechanism of Subordinate Peak Skewing of FBG Sensor during Cracks Propagation Monitoring on Aluminum Alloy Structure

et al. 2017

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“…The yield strength of the materials was 360 MPa, the ultimate strength was 490 MPa, the Poisson's ration was 33, and the Young's modulus was 72,000 MPa. Results from Reference [23] indicate that the pre-crack around the hole has a larger stress concentration and therefore has the most potential to develop the fatigue damage.…”

Section: Specimens: Materials and Geometrymentioning

confidence: 99%

Denoising of the Fiber Bragg Grating Deformation Spectrum Signal Using Variational Mode Decomposition Combined with Wavelet Thresholding

Zhang

Zhao

et al. 2019

Applied Sciences

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Damage detection using an FBG sensor is a critical process for an assessment of any inspection technology classified as structural health monitoring (SHM). FBG signals containing noise in experiments are developed to detect flaws. In this paper, we propose a novel signal denoising method that combines variational mode decomposition (VMD) and changed thresholding wavelets to denoise experimental and mixed signals. VMD is a recently introduced adaptive signal decomposition algorithm. Compared with traditional empirical mode decomposition (EMD), and it is well founded theoretically and more robust to noise samples. First, input signals were broken down into a given number of K band-limited intrinsic mode functions (BLIMFs) by VMD. For the purpose of avoiding the impact of overbinning or underbinning on VMD denoising, the mixed signals, which were obtained by adding different signal/noise ratio (SNR) noises to the experimental signals, were designed to select the best decomposition number K and data-fidelity constraint parameter α. After that, the realistic experimental signals were processed using four denoising algorithms to evaluate denoising performance. The results show that, upon adding additional noisy signals and realistic signals, the proposed algorithm delivers excellent performance over the EMD-based denoising method and discrete wavelet transform filtering.

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“…Many studies have shown that the FBG reflection spectrum was distorted due to the inhomogeneous strain field caused by damage [7]. Many damage features factors were extracted from the distorted spectra based on the response.…”

Section: Introductionmentioning

confidence: 99%

The Location Monitoring of Fatigue Crack Damage by Using the Spectral Area Extracted from FBG Spectra

Zhao

Zhang

et al. 2020

Sensors

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In this paper, a new damage feature, spectral area, was extracted to effectively detect crack location by studying the deformation mechanism of fiber Bragg grating (FBG) reflection spectra. In order to verify the robustness and reliability of spectral area to detect crack location, the following work was carried out: Firstly, the strain information was extracted by extended finite element method (XFEM) with fatigue crack propagation. The transmission matrix method (TMM) was used to simulate FBG reflection spectra using numerical results. Secondly, the fatigue crack growth monitoring experiment based on FBG sensors was carried out, and the digital image correlation (DIC) method was used to measure the strain values at the placement of FBG sensors with crack propagation. The temperature characteristic test of FBG was carried out to investigate the influence of temperature variation on the spectral area. The results presented that the spectral area was insensitive to temperature variation and experimental noise, and was greatly sensitive to the complex non-uniform strain field cause by crack damage. Moreover, compared with the 5 mm FBG sensor, the 10 mm FBG sensor showed a larger critical detection range for crack damage. Therefore, the spectral area can be used as a reliable damage feature to detect the crack location quantitatively based on the simulated and experimental results.

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Investigation on Characteristic Variation of the FBG Spectrum with Crack Propagation in Aluminum Plate Structures

Cited by 9 publications

References 17 publications

Mechanism of Subordinate Peak Skewing of FBG Sensor during Cracks Propagation Monitoring on Aluminum Alloy Structure

Mechanism of Subordinate Peak Skewing of FBG Sensor during Cracks Propagation Monitoring on Aluminum Alloy Structure

Denoising of the Fiber Bragg Grating Deformation Spectrum Signal Using Variational Mode Decomposition Combined with Wavelet Thresholding

The Location Monitoring of Fatigue Crack Damage by Using the Spectral Area Extracted from FBG Spectra

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