Abstract: Apparatus and methods are described for the improved throughput and increased reliability for inspection of critical surfaces on aircraft engine disks. Eddy current sensor arrays allow two-dimensional images to be generated for detection of cracks in regions with fretting damage. Background variations due to fretting damage and stress variations are also accommodated. These arrays are combined with instrumentation that permits parallel data acquisition for each sensing element and rapid inspection rates. Inflatable support structures behind the sensor array improve sensor durability and reduce fixturing requirements for the inspection.

Abstract: Methods are described for the use of conformable eddy-current sensors and sensor arrays for characterizing residual stresses and applied loads in materials. In addition, for magnetizable materials such as steels, these methods can be used to determine carbide content and to inspect for grinding burn damage. The sensor arrays can be mounted inside or scanned across the inner surface of test articles and hollow fasteners to monitor stress distributions. A technique for placing eddy-current coils around magnetizable fasteners for load distribution monitoring is also disclosed.

Abstract: This invention relates to apparatus for the nondestructive measurements of materials. New eddy current sensing arrays and methods are described which provide a capability for high resolution imaging of test materials and also a high probabilitity of detection for defects and flaws around features such as fasteners. The arrays incorporate unique layouts for the sensing elements, generally have essentially identical sensor arrays with sensing elements aligned in proximity to the drive elements, and conductive pathways that promote cancellation of undesired magnetic flux. These features enable the use of small sense elements that permits high resolution imaging of material properties.

Abstract: A dielectrometer with a sensor face that carries an excitation electrode driven with a varying voltage. At least two sensing electrodes and a guard electrode are also carried by the sensor face. The sensing electrodes are adapted for single or multiple penetration depth measurements into a test material. The guard electrode surrounds the sensing electrodes and is at about the same voltage as the sensing electrodes.

Abstract: An apparatus for the nondestructive measurements of materials. Eddy current sensing arrays are described which provide a capability for high resolution imaging of test materials and also a high probabilitity of detection for defects. These arrays incorporate layouts for the sensing elements which take advantage of microfabrication manufacturing capabilities for creating essentially identical sensor arrays, aligning sensing elements in proximity to the drive elements, and laying out conductive pathways that promote cancellation of undesired magnetic flux.