An Eddy Current Probe for the Detection of Sub-Superficial Defects of any Orientation

The paper introduces a novel 4-coils probe designed for Eddy Current Non-Destructive Testing on conductive materials. The key innovation lies in its capability to identify small surface and subsurface cracks regardless of their orientation. This is achieved through a suitable probe developed using two pairs of exciting coils that allow to generate two orthogonal magnetic fields. Using two excitation currents with an amplitude modulation approach, a rotation of the eddy currents induced in the conductive sample is obtained. This novel approach ensures effective detection of deep and arbitrarily oriented cracks. Both numerical tests and experimental evaluations were employed to assess the performance of the proposed probe. The probe’s effectiveness was particularly observed in detecting a buried crack measuring 5 mm in length, 1 mm in height, and 0.1 mm in thickness at depths up to 3 mm in an aluminum plate. The results demonstrated the robustness of the probe’s detection capability, affirming its potential as a reliable tool for nondestructive testing in industrial applications.