光纤布拉格传感器兰姆波检测的反射谱分析  

Reflection spectrum analysis of fiber Bragg grating sensor as Lamb wave detector

作　　者：张海燕[1] 孙修立[1] 石志东[1] 陈娜[1] 肖悦娱[1] 

机构地区：[1]上海大学通信与信息工程学院,特种光纤与光接入网省部共建重点实验室,上海200072

出　　处：《声学技术》2009年第5期605-609,共5页Technical Acoustics

基　　金：国家自然科学基金(10874110,10504020);上海市重点学科和上海市科委重点实验室项目(S30108,08DZ2231100)

摘　　要：传统的兰姆波多采用压电陶瓷换能器激发和接收。建立了新的超声兰姆波无损检测系统,其基本思想是采用布拉格光纤传感器作为兰姆波的接收器。光纤光栅传感的基本原理是通过检测光栅反射的中心波长移动实现对外界参量如超声的测量。超声作用下光纤光栅的反射谱发生变化,对超声作用下光纤光栅的反射谱变化进行了数值分析,结果表明,超声对光栅反射谱的影响与超声波长与光栅长度的比值是高度相关的。只有当这个比值相当大时,反射谱的形状才不会变化而中心波长发生偏移,此时光纤传感器可用来探测兰姆波。这个结论为利用新的兰姆波无损检测系统在布拉格光栅长度的设计和兰姆波波长的选择方面提供了有用的工具。Piezoceramic transducers have been the most commonly used method for generating and receiving Lamb waves traditionally. A new ultrasonic Lamb wave nondestructive testing （NDT） system is developed in this paper. The basic idea is to use a fiber Bragg grating （FBG） sensor as an acoustic receiver of ultrasonic Lamb waves generated by a piezoceramic transducer. The basic principle of FBG is to measure external force such as ultrasound field by detecting the center wavelength shift of the light reflected from the grating. The reflection spectrum changing of a FBG due to the interations with an ultrasound wave has been numerically analyzed. The results show that the influence of ultrasonic field on grating spectrum is highly correlated to the ratio between the ultrasonic wavelength and the grating length. Only when the ratio is quite larger, the center wavelength of reflection spectrum shifts while the shape of the grating remains unchanged, which provide useful tools for the design of gage length of FBG sensor and the choice of Lamb wave wavelength when the new NDT system is used for Lamb wave detection.

关 键 词：兰姆波 布拉格光栅 反射谱 

分 类 号：O426.4[理学—声学]