Choi Bo-Hun, Kwon Il-Bum
Opt Express. 2015 Mar 9;23(5):6867-77. doi: 10.1364/OE.23.006867.
We propose a distributed residual strain sensor that uses an Al-packaged optical fiber for the first time. The residual strain which causes Brillouin frequency shifts in the optical fiber was measured using Brillouin optical correlation domain analysis with 2 cm spatial resolution. We quantified the Brillouin frequency shifts in the Al-packaged optical fiber by the tensile stress and compared them for a varying number of Al layers in the optical fiber. The Brillouin frequency shift of an optical fiber with one Al layer had a slope of 0.038 MHz/με with respect to tensile stress, which corresponds to 78% of that for an optical fiber without Al layers. After removal of the stress, 87% of the strain remained as residual strain. When different tensile stresses were randomly applied, the strain caused by the highest stress was the only one detected as residual strain. The residual strain was repeatedly measured for a time span of nine months for the purpose of reliability testing, and there was no change in the strain except for a 4% reduction, which is within the error tolerance of the experiment. A composite material plate equipped with our proposed Al-packaged optical fiber sensor was hammered for impact experiment and the residual strain in the plate was successfully detected. We suggest that the Al-packaged optical fiber can be adapted as a distributed strain sensor for smart structures, including aerospace structures.
我们首次提出了一种使用铝封装光纤的分布式残余应变传感器。利用具有2厘米空间分辨率的布里渊光相关域分析来测量导致光纤中布里渊频移的残余应变。我们通过拉伸应力对铝封装光纤中的布里渊频移进行了量化，并比较了光纤中不同铝层数情况下的频移。具有一层铝的光纤的布里渊频移相对于拉伸应力的斜率为0.038 MHz/με，这相当于无铝层光纤的78%。去除应力后，87%的应变作为残余应变保留下来。当随机施加不同的拉伸应力时，由最高应力引起的应变是唯一被检测为残余应变的。为了进行可靠性测试，在九个月的时间跨度内对残余应变进行了反复测量，除了有4%的减小外，应变没有变化，这在实验的误差容限范围内。对配备了我们提出的铝封装光纤传感器的复合材料板进行了锤击冲击实验，并成功检测到了板中的残余应变。我们认为，铝封装光纤可作为智能结构（包括航空航天结构）的分布式应变传感器。
