Portable, Hand-Held Inspection System for Aircraft Components

New technology is needed for the nondestructive detection and characterization of defects in aerospace structures, particularly those with compex shapes that are used in high stress environments that accelerate degradation. Existing nondestructive evaluation (NDE) techniques, based on ultrasonics, eddy-currents, and x-radiography, do not have the capabilities needed for real-time defect detection and imaging using highly portable instrumentation. RMD proposes and NDE instrument based on an array of magnetoresistive (MR) sensor elements used to produce real-time magnetic fields images of cracks, corrosion, and other defects in a wide range of components, some with complex shapes. Correlating the magnetic field properties at many points, with the positions where the measurements are made, allows the generation of real-time, 3-D images of defects. During Phase I, high quality images were made of simulated cracks 5 mils wide and 25 mils on the inside of a 1/4 inch thick steel sample. The images were made by scanning the outside of the sample. MR sensors have achieved sensitivity of approximately 1.0 x 10-10 T/√Hz. MR sensors have bandwidth greater than 1 GHz, they can withstand forces of 100,000g, and temperatures over 2000C. Phase II will result in a portable, cost effective NDE instrument for imaging defects in the filed under a variety of environmental conditions. The PI and his collaborators have been able to develop MR sensor systems for recovering data on obsolete or damaged magnetic tapes, and for detecting cracks and corrosion in sheet metal. Phase I tests indicate that the new technology is capable of detecting second layer defects.