Shaped Field Giant Magnetoresistive Sensor Arrays for Materials Testing

Shaped field Giant Magnetoresistive Sensor Arrays offer substantially increased depth of sensitivity and potential to provide 3-dimensional absolute property imaging for conducting and magnetic media. The Phase I demonstrated the capability of Meandering Winding Magnetometer (MWM) drive winding constructs with GMR sensing elements to (1) detect and image 3% material loss in a 0.25 inch thick aluminum plate, (2) detect corrosion damage in a military aircraft component, (3) use a forward model of the sensor interactions with layered media to calibrate in ?air,? without standards, and accurately measure absolute electrical conductivity and layer thickness, (4) measure and monitor temperature variations for an aluminum plate through another 0.25 inch aluminum plate with an additional 0.5 inch air gap between plates, (5) independently measure variations in stress (i.e., through its relationship with magnetic permeability) on a steel plate through a 0.25 inch aluminum plate and variations in an approximately 0.12 inch air gap between plates, and to (6) operate a three channel GMR-MWM sensor array with JENTEK?s commercial impedance instrumentation. These demonstrations completely satisfied the Phase I objectives. The proposed Phase II effort will develop conformable MWM-Arrays with GMR sensing elements and distributed winding designs for imaging hidden damage and geometric features.