Dimensional analysis approach for simultaneous estimation of electrical conductivity and lift-off in eddy current testing

Accurate estimation of electrical conductivity and lift-off is crucial in eddy current testing (ECT) to assess material properties and ensure inspection accuracy. Traditional methods often struggle with computational complexity, parameter dependency, and limited applicability to real-time scenarios. In this article, we propose an innovative methodology based on dimensional analysis and Buckingham’s π theorem to simultaneously estimate electrical conductivity and lift-off with reduced computational effort. The methodology reformulates the inversion problem in a dimensionless form, significantly simplifying the inverse estimation process. The proposed solution is based on a single or multifrequency strategy, allowing efficient real-time processing and ensuring good accuracy. The experimental campaign shows that the proposed methodology generally achieves errors lower than 3% for electrical conductivity and 2% for liftoff, confirming the robustness and repeatability of the method over different materials and frequency ranges. Compared to conventional techniques, the proposed methodology provides a computationally efficient and scalable solution, which makes it suitable for online and real-time industrial applications.