This paper focuses on damage detection, localization and quantification in metallic plates using an array of sensors and
an advanced feature extraction algorithm. The Matching Pursuit Decomposition (MPD) algorithm is used for timefrequency
signal analysis. Using MPD, measured signals are decomposed into multiple wave modes. The individual wave modes are analyzed to determine the cause of signal changes and the location of the damage. An aluminum plate made of 6061 alloy was instrumented with piezoelectric transducers and used for testing and validation of the proposed concept.
This paper presents a novel Fiber-Bragg Grating interrogation system and its validation for detection of Lambwaves
and acoustic emission events on both aluminum and composite substrates. The system utilizes a robust laser
demodulation technique for FBG interrogation, based upon a simple laser wavelength tracking scheme. This technique
enables detection of much higher frequency strains than previous FBG interrogation techniques, enabling the use of FBG
sensors in acousto-ultrasonic structural health monitoring schemes such as Lamb-wave pitch-catch and acoustic emission
detection in the presence of a quasistatic strain background. The principles of the FBG interrogation system are
presented, including validation of the system for detection of ultrasonic Lamb waves, and results from a 4-point bending
test of a braided composite tube wherein the FBG system was used to detect crack-growth induced AE events on the
braided tube. The AE data agreed well with damage index values measured by a commercial acousto-ultrasonic system.
This paper presents the development of a Bragg grating interrogation technique for measurements of strain, stress,
temperature, and ultrasonic waves. The sensor design and instrumentation technique offer a number of advantages including
sensor compactness, lightweight, low-cost, and multiplexing capability for damage detection and corrosion monitoring of
advanced structures and components. Using a robust lock-in laser-based demodulation technique, simultaneous
measurements of strain, temperature, and damage induced acoustic fields can be performed with high precision, high
resolution, and high sensitivity. The interrogated sensor device containing an array of optical Bragg grating fibers and
waveguides can be surface mounted on monitoring structures for non-destructive testing applications including highresolution
strain measurement and high sensitivity damage and corrosion monitoring.