Energy, Electromagnetic Testing
A Magnetic Polarity–Controlled Eddy Current Method for Multidirectional Discontinuity Detection in Tubes
ABSTRACT
To address high system complexity and missed detection of orientation-specific discontinuities in existing eddy current inspection methods for tubes, this paper proposes a magnetic polarity–controlled eddy current testing approach for inspecting the inner surfaces of tubes, focusing on notch-like discontinuities with rectangular cross sections. Two series-connected excitation coils wound in opposite directions generate a radially polarized magnetic field, inducing eddy currents that couple effectively with discontinuities at various orientations for multidirectional detection. The detection principle is explained based on the directional characteristics of the electromagnetic field, validated through finite element simulation, and confirmed experimentally on steel tube specimens with machined rectangular discontinuities. Results demonstrate that the proposed method can effectively detect artificial discontinuities measuring 12 mm × 0.5 mm × 0.5 mm at different orientations while maintaining low system complexity and reduced signal processing difficulty. This work presents a new approach to eddy current detection of multidirectional discontinuities within tubes.
KEYWORDS: eddy current testing, magnetic polarity controlled, tube inspection, nondestructive testing, finite element simulation
https://doi.org/10.32548/2026.me-04574
