Multi-frequency Eddy Current Testing using a GMR based Instrument

The paper proposes the use of a suitable multi-frequency approach applied to a novel instrument for the eddy current non-destructive testing on conductive materials. The instrument is composed by a smart eddy current probe, based on a Giant Magneto Resistance sensor, and a suitable processing unit. Key features of the proposed instrument are the capability to detect, locate and characterize thin defects as superficial and subsuperficial cracks. The proposed multi-frequency solution, together with a suitable data processing, allow both to increase the sensitivity in the defect detection and to improve the ability to evaluate the defect characteristics in terms of shape and dimension.