Development of a Magnetic/Eddy-Current Sensing System For Simultaneous Estimation of Electrical Conductivity and Thickness in Non-Ferrous Metal Plates

This article presents the development of a nonferrous-metal magnetic/eddy-current (NFM-M/EC) sensing system for simultaneous estimation of electrical conductivity and thickness in nonferrous metal plates. The distributed current source (DCS) method models the axisymmetric magnetic/eddy-current fields for the sensor design. An anisotropic magnetoresistive sensor is used to detect the change in magnetic flux density caused by the induced eddy currents in the test plates. The frequency-mapping method for sweep frequency measurements is numerically validated. Calibration between the model and experimental data by the mesh refinement method is introduced to improve the accuracy of estimations efficiently. The DCS method is verified numerically by comparing it with finite-element analysis. The proposed sensing system design is tested on four different materials with varying thicknesses. Accurate estimations in experiments substantiate the NFM-M/EC sensing system as a new alternative for nondestructive detection.