<title>Introduction to the Meandering Winding Magnetometer (MWM) and the grid measurement approach</title>

Abstract

A new sensor called the Meandering Winding Magnetometer (MWM) and associated grid measurement algorithms is described. The MWM can be used to determine property profiles for ferrous and nonferrous components, to provide repeatable and reproducible measurements on curved surfaces or inspection of difficult to access locations, and to detect and characterize cracks. This paper describes the application of the MWM to detection and characterization of early stage fatigue damage in aluminum and stainless steel. Other potential applications include coating characterization, case depth measurement, crack detection, and embedded sensing. The MWM is a thin and conformable sensor that incorporates both eddy current type sensing and magnetic induction sensing methods to measure conducting and magnetic properties of nonferrous and ferrous metals. The grid measurement approach is a model-based technique used to measure two properties independently, at a single frequency. This grid method also provides a convenient framework for MWM system calibration and processing of multiple frequency data. For example, this permits measurement over a wide frequency range using a single MWM sensor geometry. This paper provides a general introduction to the MWM technology and specific capability demonstrations on ferrous and nonferrous alloys.