A Space Discretized Ferromagnetic Model for Non-Destructive Eddy Current Evaluation

Accurate magnetic material laws are necessary to understand and interpret electrical signals generated by eddy current testing non-destructive control technique. Taking into account simultaneously, both microscopic and macroscopic eddy currents, a numerical resolution is obtained which leads to the global magnetic behavior that can be compared to measured quantities. The 2-D or 3-D (depending on the dimension of the test sample) finite differences space discretization is used for the resolution of the diffusion equation and dynamic hysteresis model is locally simultaneously solved for the microscopic eddy currents (domain wall movements) consideration. Local cracks defects are considered in this model as a variation in the local electrical conductivity and magnetic permeability. The numerical issues such as the proposed solutions for the implementation are described in this paper.