Acoustic Emission Sensor for Spacecraft Applications

Sensors offering accurate real-time monitoring and prediction of damages on vehicle subsystems are important for NASA to reduce both time and costs required for operations involving vehicle inspection. Fiber Bragg Gratings are promising candidates for such sensors because of their high sensitivity in detecting crack growth in metals, delaminations in fiber composites, and chemical degradation. While silica based fiber sensors have been developed for spacecraft strain and stress monitoring , they lack the sensitivity required for advanced monitoring applications, such as detecting weak acoustic wave signals initiated by aerospace structure?s micro-cracks in a noisy, vibrating environment experienced by space systems. Los Gatos Research proposes a high performance acoustic emission sensor based upon inscribing surface relief Bragg gratings in polymer waveguides. The combined superior mechanical property of polymer waveguides and inherent wavelength-encoded nature of the output of waveguide Bragg gratings offer a cost-effective, high detection sensitivity solution to NASA?s Vehicle Health Monitoring program. The Phase I program will demonstrate the acoustic emission response by the polymer waveguides and their applications for real-time monitoring and prediction of damages on vehicle subsystems.