Sbarufatti Claudio, Beligni Alessio, Gilioli Andrea, Ferrario Maddalena, Mattarei Marco, Martinelli Mario, Giglio Marco
Dipartimento di Meccanica, Politecnico di Milano, Milano 20156, Italy.
Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano 20133, Italy.
Materials (Basel). 2017 Jul 13;10(7):794. doi: 10.3390/ma10070794.
A novel fiber optic sensing technology for high frequency dynamics detection is proposed in this paper, specifically tailored for structural health monitoring applications based on strain wave analysis, for both passive impact identification and active Lamb wave monitoring. The sensing solution relies on a fiber optic-based interferometric architecture associated to an innovative coherent detection scheme, which retrieves in a completely passive way the high-frequency phase information of the received optical signal. The sensing fiber can be arranged into different layouts, depending on the requirement of the specific application, in order to enhance the sensor sensitivity while still ensuring a limited gauge length if punctual measures are required. For active Lamb wave monitoring, this results in a sensing fiber arranged in multiple loops glued on an aluminum thin panel in order to increase the phase signal only in correspondence to the sensing points of interest. Instead, for passive impact identification, the required sensitivity is guaranteed by simply exploiting a longer gauge length glued to the structure. The fiber optic coherent (FOC) sensor is exploited to detect the strain waves emitted by a piezoelectric transducer placed on the aluminum panel or generated by an impulse hammer, respectively. The FOC sensor measurements have been compared with both a numerical model based on Finite Elements and traditional piezoelectric sensors, confirming a good agreement between experimental and simulated results for both active and passive impact monitoring scenarios.
本文提出了一种用于高频动力学检测的新型光纤传感技术，该技术专门针对基于应变波分析的结构健康监测应用进行了定制，可用于被动冲击识别和主动兰姆波监测。该传感解决方案依赖于一种基于光纤的干涉测量架构以及一种创新的相干检测方案，该方案以完全被动的方式获取接收到的光信号的高频相位信息。传感光纤可以根据特定应用的要求布置成不同的布局，以提高传感器的灵敏度，同时在需要进行点测量时仍确保有限的标距长度。对于主动兰姆波监测，这导致传感光纤布置成多个环，粘贴在铝薄板上，以便仅在感兴趣的传感点处增加相位信号。相反，对于被动冲击识别，只需利用粘贴在结构上的更长标距长度即可保证所需的灵敏度。利用光纤相干（FOC）传感器分别检测放置在铝板上的压电换能器发出的应变波或由脉冲锤产生的应变波。将FOC传感器的测量结果与基于有限元的数值模型以及传统压电传感器进行了比较，证实了在主动和被动冲击监测场景下，实验结果与模拟结果之间具有良好的一致性。
