Zhao Yan, Hu DianYin, Zhang Meng, Dai Wei, Zhang Weifang
Research Institute of Aero-engine, Beihang University, 37 Xueyuan Rd., Haidian Dist., Beijing 100191, China.
School of Energy and Power Engineering, Beihang University, 37 Xueyuan Rd., Haidian Dist., Beijing 100191, China.
Sensors (Basel). 2020 Apr 22;20(8):2375. doi: 10.3390/s20082375.
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.
本文通过研究光纤布拉格光栅（FBG）反射光谱的变形机制，提取了一种新的损伤特征——光谱面积，以有效检测裂纹位置。为了验证光谱面积检测裂纹位置的鲁棒性和可靠性，开展了以下工作：首先，采用扩展有限元法（XFEM）结合疲劳裂纹扩展来提取应变信息。利用数值结果通过传输矩阵法（TMM）模拟FBG反射光谱。其次，开展了基于FBG传感器的疲劳裂纹扩展监测实验，采用数字图像相关（DIC）方法测量随着裂纹扩展在FBG传感器放置位置处的应变值。进行了FBG的温度特性测试，以研究温度变化对光谱面积的影响。结果表明，光谱面积对温度变化和实验噪声不敏感，而对裂纹损伤引起的复杂非均匀应变场非常敏感。此外，与5mm的FBG传感器相比，10mm的FBG传感器对裂纹损伤显示出更大的临界检测范围。因此，基于模拟和实验结果，光谱面积可作为一种可靠的损伤特征来定量检测裂纹位置。
