Analysis of incremental and differential permeability in NDT via 3D-simulation and experiment

This paper investigates differential and incremental permeability in non-destructive testing application, evaluated by two different technologies, 1) using a "yoke probe head" principal, via a surrounding coil; and 2) via a local receiver coil situated over the sample. The detected signals are simulated using 3D non-linear finite element method. The dynamic vector hysteresis nature of the ferromagnetic part is considered. The incremental permeability is calculated analytically and the profile is compared to measurement data. The FEM computed signals of both NDT technologies are compared to the experimental results, and show good agreement.