College of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024, China.
Sensors (Basel). 2013 Dec 27;14(1):431-42. doi: 10.3390/s140100431.
The Brillouin optical time-domain analysis (BOTDA)-based optical fiber method has been proposed to measure strain variations caused by corrosion expansion. Spatial resolutions of 1 m can be achieved with this kind of Brillouin sensor for detecting the distributed strain. However, when the sensing fiber is wound around the steel rebar in a number of circles in a range of several meters, this spatial resolution still has limitations for corrosion monitoring. Here, we employed a low-coherent fiber-optic strain sensor (LCFS) to survey the performance of Brillouin sensors based on the fact that the deformation measured by the LCFS equals the integral of the strains obtained from Brillouin sensors. An electrochemical accelerated corrosion experiment was carried out and the corrosion expansion was monitored by both BOTDA and the LCFS. Results demonstrated that the BOTDA can only measure the expansion strain of about 1,000 με, which was generated by the 18 mm steel rebar corrosion, but, the LCFS had high sensitivity from the beginning of corrosion to the destruction of the structure, and no obvious difference in expansion speed was observed during the acceleration stage of the corrosion developed in the reinforced concrete (RC) specimens. These results proved that the BOTDA method could only be employed to monitor the corrosion inside the structure in the early stage.
基于布里渊光时域分析（BOTDA）的光纤方法已被提出，用于测量腐蚀膨胀引起的应变变化。这种布里渊传感器可以实现 1 m 的空间分辨率，用于检测分布式应变。然而，当传感光纤在几米范围内缠绕在钢筋上的几圈时，这种空间分辨率对于腐蚀监测仍然存在局限性。在这里，我们利用低相干光纤应变传感器（LCFS）来评估基于布里渊传感器的性能，其依据是 LCFS 测量的变形等于从布里渊传感器获得的应变的积分。进行了电化学加速腐蚀实验，并通过 BOTDA 和 LCFS 监测腐蚀膨胀。结果表明，BOTDA 只能测量约 1000 με的膨胀应变，这是由 18 毫米钢筋腐蚀产生的，但 LCFS 从腐蚀开始到结构破坏都具有很高的灵敏度，在钢筋混凝土（RC）试件中腐蚀加速阶段，没有观察到膨胀速度的明显差异。这些结果证明，BOTDA 方法只能用于监测结构内部的腐蚀在早期阶段。
