Direct computation of static difference magnetic field in nonlinear magnetic materials and application to shape reconstruction of damaged areas in aging materials

In order to accurately compute the magnetic field variation due to changes in material properties (e.g. material aging), we propose a technique that computes the difference magnetic field directly. Nonlinear materials are analyzed by means of the polarization technique. The linear field problem is solved using a fast Green function approach. A two-dimensional formulation is validated upon comparison with measurement data. Then, it is used as fast forward solver for a neural network approach to the inverse problem of reconstructing the shape of the aged material area in a plate. Finally, results of reconstruction, based on 500 case database simulations of a yoke and plate geometry, are presented, indicating the good quality of the reconstruction.