用于非线性兰姆波检测的高灵敏度宽带光纤光栅传感器

光纤传感器因其灵敏度高,已逐渐应用于超声检测的研究中,但大多数光纤传感器的频带响应范围有限,约为几百k Hz,很难检测到更高频率的信号。所提出的光纤布拉格光栅(Fiber Bragg Grating,FBG)传感器的高频检测范围可以达到4 MHz左右,大大提高了其检测带宽范围。文中将传感器应用于304不锈钢板兰姆波的非线性检测,同时与传统超声换能器的检测结果做对比。实验结果表明,用脉冲波激励信号时,FBG传感器可以检测到钢板兰姆波的基频到五倍频信号,表明FBG在检测兰姆波非线性上是有很大潜力的。

A wide bandwidth and high sensitivity FBG sensor for nonlinear Lamb wave detection

Due to high sensitivity, optic fiber sensor has been gradually used in acoustic detection. But the upper limit of frequency response for most optic fiber sensors is about hundreds of kHz. So it is difficult to detect higher frequency signal. In this paper, a FBG sensor of detection bandwidth reaching about 4 MHz is designed, and the FBG sensor as well as a traditional ultrasonic transducer is used to detect the nonlinear effect of Lamb wave in 304 stainless steel plate respectively. By comparing the results of the two experiments, it can be found that both the FBG sensor and the traditional transducer can detect the fundamental and second harmonic waves in the steel plat, and the weak 3^rd/4^th harmonic waves as well, which is shown that FBG has a great potential in detecting nonlinear Lamb waves.