基于长周期光纤光栅微弯特性的智能结构振动监测

Vibration monitoring of smart structure using micro-bending characteristic of long-period fiber grating

首先研究了长周期光纤光栅的微弯特性,结果表明,其固定波长处的光功率与LPFG的弯曲度成线性,由此将其粘贴于试件上,研究了当试件受到垂直周期力载荷而发生弯曲并随之振动时LPFG的动态响应特性,利用布拉格光栅反射特性获得确定波长处的窄带光作为LPFG的入射光源,通过对固定波长处的光功率探测,进而实现对试件从2Hz到2000Hz范围内的振动监测。由实验采集到的振动信号时域波形及其频谱表明,基于弯曲的LPFG振动传感器具有很好的动态响应特性,其频谱与激振信号频率完全吻合,能够应用于智能材料与结构的健康监测。

The micro-bending characteristic of LPFG is discussed firstly, it is found that the light power at fixed wavelength is linear to the curvature of LPFG, when the LPFG is glued onto an experimental laminate sample and certain fixed wavelength light is obtained using the reflective characteristic of Bragg grating and used as the input light source of LPFG. By detecting the transmission power at the resonance wavelength of the LPFG, the vibration monitoring of the laminate sample from 2 Hz to 2 000 Hz is realized. The acquired vibration signal and the fast Fourier transform of the experiment data show that the vibration spectrum is agree with the exciting frequency. It is hopeful that the LPFG vibration sensor can be used in health monitoring of smart material and structure.