| New methods for structural health monitoring are being assessed, especially in high-performance, extreme environment, safety-critical applications. One such application is for composite cryogenic fuel tanks. The work presented here attempts to characterize and investigate the feasibility of using imbedded piezoelectric sensors to detect cracks and delaminations under cryogenic and ambient conditions. A variety of damage detection methods and different sensors are employed in different composite plate samples to aid in determining an optimal algorithm, sensor placement strategy, and type of imbedded sensor to use. Statistical and analytical techniques are then used to determine which method is most desirable for detecting a specific type of damage. These results are also compared with previous work using externally mounted sensors. Results and optimized methods from this work can then be incorporated into a larger composite structure to validate and assess its structural health. This could prove to be important in the development and qualification of any 2 nd generation reusable launch vehicle where composites are used to fabricate structural elements. At the very least, these sensors could also be used to monitor cryogenic liquid propellant level since they seem to respond well to changes in temperature. |
