Eddy current testing can be used to interrogate steels but it is hampered by the lift-off distance of sensor. Previously, point intersection (LOI) feature has been found for pulsed eddy (PEC) testing. In this paper, a invariant inductance (LII) proposed multi-frequency (MEC) testing, which merely targets ferromagnetic steels. That is, at certain working frequency, measured signal nearly immune ...

Thickness measurements of metallic plates are mandatory in many industrial scenarios. Methods based on Eddy Current Testing (ECT) ideal for fast and accurate online contact–less thickness measurements, making them very attractive the Industry 4.0 scenario. This contribution is focused a specific robust ECT technique proposed past by scientific community. The main limitation its applicability to...