Distributed fiber optic strain sensing for crack detection with Brillouin shift spectrum back analysis
Distributed fiber optic strain sensing for crack detection with Brillouin shift spectrum back analysis
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DOI：
10.1177/14759217231206857
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发表时间：
2023-11
期刊：
影响因子：
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通讯作者：
Ruonan Ou;Linqing Luo;Kenichi Soga
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文献类型：
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作者：
Ruonan Ou;Linqing Luo;Kenichi Soga
材料开裂是导致结构失效的主要机制之一。分布式光纤传感（DFOS）可以沿光纤沿着分布测量应变分布。然而，使用布里渊-DFOS系统（布里渊光时域分析/反射计（BOTDA/R））的传统应变测量具有分米级的空间分辨率，使得难以测量由亚毫米裂纹产生的高度局部化的应变。针对BOTDA/R系统在空间分辨率上的缺陷，提出了一种基于布里渊散射谱分解的裂纹分析方法。该方法使用非负最小二乘算法来反算每个测量点周围的空间分辨率内的应变分布。通过矿渣水泥-水泥-膨润土脆性梁的四点弯曲试验，验证了该方法的有效性。对于0.76mm的窄裂纹，裂纹宽度估算误差可提高到± 0.005mm。
Material cracking is one of the key mechanisms contributing to structural failure. Distributed fiber optic sensing (DFOS) can measure the strain profile along optical fiber distributively. However, the conventional strain measurement using a Brillouin-DFOS system (Brillouin optical time-domain analysis/reflectometry (BOTDA/R)) has a decimeter-order spatial resolution, making it difficult to measure the highly localized strain generated by a sub-millimeter crack. This paper introduces a crack analysis method based on decomposing the Brillouin scattering spectrum to overcome the spatial resolution induced crack measurement limitation of the BOTDA/R system. The method uses the non-negative least squares algorithm to back-calculate the strain profile within the spatial resolution around each measurement point. The performance of this method is verified by a four point bending test of a brittle slag cement-cement-bentonite beam. The crack width estimation error is improved to ±0.005 mm for a crack as narrow as 0.76 mm.