Acoustic Emission Detection Using Fiber Bragg Gratings and Fast Signal Processing

"The proposed program would develop high-speed optical fiber Bragg grating sensors and signal processing methods for the near real-time detection of acoustic emission events and associated material damage in advanced aircraft structures. Acoustic emissionis associated with the occurrence and accumulation of microstructural damage in materials. By detecting the amplitude and frequency characteristics of such pulsed ultrasonic stress waves it is possible to determine when structural components are loaded tonew maximum levels of stress, and to anticipate the onset of material failure. Optical fiber Bragg grating-based sensors offer a means of implementing networks of acoustic emission sensor elements on large structures such as aircraft. The proposedprogram would develop near real-time signal processing systems for such sensors, to enable high frequency response to acoustic emission, and thus the ability to characterize damage mechanism sources and pre-failure events. NanoSonic Inc. would work withthe Fiber & Electro-Optics Research Center on campus at Virginia Tech on this program through a small subcontract. University researchers at FEORC were among the first to demonstrate the detection of acoustic emission using fiber sensors and systems inthe 1970s and 1980s, and to quantitatively compare fiber sensors and conventional 2.25 MHz acoustic emission piezoelectric transducers. Acoustic emission (AE) is an important tool used for t