DAMAGE IDENTIFICATION IN CFRP LAMINATES USING BROADBAND ULTRASONIC WAVES

摘要

For damage detection in carbon fiber reinforced plastic (CFRP) laminates, health monitoring techniques using ultrasonic waves are effective. Currently, piezo-ceramic (PZT) elements are used for sending and receiving the ultrasonic waves. Hence the waves are generally narrowband. However, since the macro fiber composite (MFC) actuator developed at NASA Langley Research Center and a fiber Bragg grating (FBG) sensor, which is a kind of optical fiber sensors, do not have resonance frequency, the system combining these elements can employ broadband ultrasonic waves. Thus more information can be extracted from the received waves. In this research, the authors constructed the system consisting of an MFC actuator to generate Lamb waves and an FBG sensor to receive the propagated waves and applied this system to an aluminum plate and a CFRP laminate to examine the broadband characteristic. As a result, this system proved to be able to send and receive more broadband ultrasonic and reflect the mode dispersion of Lamb wave more clearly compared with the case using PZTs that had the resonance frequency.