Underwater Structural Health Monitoring of Composite Navy Propellers

Composite materials are beginning to be widely utilized throughout the military and commercial sectors. These advanced materials offer several advantages, including high strength to weight ratios, manipulative properties, and corrosion resistance. Of interest is the use of composite materials in Navy propellers where improvements in dynamic and acoustic performance are possible along with weight savings and reduced maintenance. However, lack of legacy design data and concerns over fatigue, environmental stability, damage tolerance, and other issues exist. There is consequently a high risk assigned to the use of advanced composites. To mitigate the risk, composites structures must be extensively evaluated at significant cost and overdesigned with a high factor of safety, often negating several of the achievable advantages. Structural health monitoring (SHM) can be implemented to reduce qualification testing and overdesign by characterizing design flaws in the development process and identifying material damage while in-service prior to catastrophic failure. Luna Innovations Incorporated is proposing to apply its embedded fiber optic strain monitoring and health management system for Navy propellers. The proposed system will be flexible in nature, capable of supporting a variety of cross-cutting structural strain sensing and health monitoring applications and readily integrated into the platform.