Description: NASA needs sensor systems to inspect space structures with minimum human interaction. These systems must be highly integrated and self-sufficient, low mass, simple to operate, provide reliable information, and use little command processing power. Eddy current testing (ECT) is a widely practiced and critically important nondestructive evaluation (NDE) method used in aerospace, yet it relies on decades-old wire-coil sensors and scanning. RMD, in collaboration with Wyle Laboratories, proposes a revolutionary structural imaging and NDE technology based on a permanently affixed, flexible sheet containing a two-dimensional array of microscopic, directionally sensitive, solid-state eddy current sensors. The modular sensing sheet could be added to the spacecraft while in space or before launch. The sensing sheet will be thin (approximately 100 um thick) and highly flexible so that it can be mounted on curved surfaces. Energy independent, wireless arrays could be affixed underneath thermal insulation, paint or other coatings, and images created by a CPU integrated on the sensor array. These images permit structural assessment and NDE of many components throughout the lifetime of a mission. The system will be largely independent of the command computer and power systems, have little external wiring, and require almost no human attention.

Benefits: The advanced ECT, NDE and structural analysis technologies proposed here would enable inspectors to detect extremely small defects with a simple to install, operate and interpret NDE technology. Eddy current testing is the most widely used NDE technique with a market value in excess of $200M/year in the US alone. Some of the commercial market areas where the new technology has promise include: pipelines, heat exchangers, oil refineries, aircraft, ship and other transport vehicle inspection, jet engine inspection, manufacturing and QA of metallic components.

The proposed technology provides an entirely new method for structural analysis and NDE that permits the long-term high resolution detection of minute defects and aging effects in difficult to access areas. The proposed NDE technology will be useful for inspecting crew compartments, fuel tanks, flight surfaces, support structures, engine casings, titanium castings, hydraulic lines and other components that are made of standard or advanced metallic materials. The technology will permit inspection of thick components in 3-D. For materials testing and development, incipient defects can be detected and their propagation monitored and analyzed during aging. Since the technology can be used to improve manufacturing and the selection of materials, and to test finished components and aging systems, it will have a broad impact on the efficiency and effectiveness of NASA missions.