Meandering Winding Magnetometer Array Eddy Current Sensors for Detection of Cracks in Regions with Fretting Damage

摘要

Improved throughput and increased reliability are required for inspection of critical surfaces on aircraft engine disks. Specific requirements for reliable detection of cracks in regions with fretting damage can be addressed by a high resolution eddy current sensor array, called the meandering winding magnetometer (MWM) array, that produces two dimensional (C-scan) images showing detected cracks. Inspection results for actual service exposed disks with verified cracks are provided. The inspection is accomplished in less than 30 s per slot, using a simple manual scanner with a single axis position encoder. These results are obtained after calibration in air only, without the use of reference standards. Results are also presented from a limited probability of detection (POD) study with Engine Structural Integrity Program flat specimens, including a comparison with conventional eddy current sensor performance and other eddy current sensor arrays. A description of the MWM sensor and model based grid methods for property estimation was first published in the March 1993 issue of Materials Evaluation. This article provides a brief overview of subsequent advances of this conformable eddy current sensor and presents results for engine slots with cracks in regions with fretting damage.