9560415 Tiernan This Small Business Innovation Research Phase I project will develop a nondestructive evaluation (NDE) method based on sensors containing elements of giant magnetoresistance (GMR) material. New techniques are needed for the NDE of anomalies and stresses in metal structures used in buildings, bridges, and aircraft components. Current techniques based on visual inspections, eddy current, X-ray radiography, and acoustic emissions suffer from limitations in inspection capability, speed of inspection, and cost of inspection. The GMR effect has resulted in the development of magnetic field sensors with extremely high signal-to-noise levels capable of detecting extremely weak magnetic fields under ambient conditions. The microfabrication techniques used to form these sensors are well suited to the construction of low cost sensor arrays with a wide range of geometries. Magnetic methods have been shown to be capable of detecting anomalies such as cracks and for estimating the stresses in and around welds in steel components. With proper sensor design it is possible to use magnetometry to obtain high resolution, three-dimensional information concerning the internal structure and stress of a component. This project will develop a sensor array based on GMR material and combine it with instrumentation and analytical concepts that will permit the 3-D imaging of metal components. A predictive capability will be developed to assess the mechanical integrity of components analyzed with the NDE system. A simple-to-use, field-portable NDE technique for metallic structures would find many applications including the inspection of bridges, buildings, and aircraft. The flexible sensor would permit the inspection of a wide range of different sample shapes. Rapid, high resolution images would permit practical cost effective inspections. The ability to predict mechanical degradation would provide critical insight concerning which structures are severely damaged and which can rem ain in service. The sensors will be simple and inexpensive to fabricate and the support electronics required is available so, in addition to high performance, it should be possible to manufacture the system at a reasonable cost.
