Ultrasonic Lamb wave mode conversion to optical fiber guided mode　with varying input conditions

摘要

In structural health monitoring (SHM) applications, one of the advantages of utilizing a surface bonded fiber Bragggrating (FBG) sensor for damage detection is its increased sensitivity in collecting ultrasonic waves. Recent studies havedemonstrated that for a certain bonding condition the output FBG response can be increased by bonding the optical fiberat a distance away from the FBG to collect optical fiber guided wave (L_(01) mode) that is converted from S_0 Lamb wave,referred as remote bonding. However in order to apply the remote bonding configuration in practical situations, the S0mode conversion to L01 mode through an adhesive bond under various conditions must be characterized. This workinvestigates how the coupled L01 mode changes with varying input S_0 mode frequency and angle of incidence through anadhesive bond. The goal of this work is to better understand the S_0 mode conversion to the L_(01) mode in order toimplement the remote bonding configuration for an improved SHM of a structure.