Local electromagnetic investigations on electrical steel FeSi 3% via 3MA micromagnetic NDT system

Speaker:
Gabi, Yasmine; Fraunhofer IZFP; Germany

Authors:
Gabi, Y.; Fraunhofer Institute for Nondestructive Testing IZFP; Germany
Böttger, D.; Fraunhofer Institute for Nondestructive Testing IZFP; Germany
Straß, B.; Fraunhofer Institute for Nondestructive Testing IZFP; Germany
Wolter, B.; Fraunhofer Institute for Nondestructive Testing IZFP; Germany
Conrad, C.; Fraunhofer Institute for Nondestructive Testing IZFP; Germany
Leinenbach, F.; Fraunhofer Institute for Nondestructive Testing IZFP; Germany

ID: ECNDT-0500-2018
Download: PDF
Session: Modeling and data processing Electromagnetic Techniques 1
Room: J2
Date: 2018-06-12
Time: 09:00 - 09:20

Cutting of electrical steel sheets to a desired shape induces strain at the vicinity of the cutting edges. These induced strains impair the permeability and deteriorate the performance of electrical machines by adversely affecting the flux density distribution and increasing the losses. Studying of the manufacturing effects on the electrical core requires accurate measurement methods. There are a number of proven methods, i.e. temperature time method, electromagnetic macroscopic standard characterization and calculation of total losses which are correlated directly to Bloch wall motion, rotation phenomena via losses evaluation (hysteresis, eddy current and excess) and to the microstructure: dislocation density, grain size, etc. Those methods are sometimes insufficient due to the global macroscopic response and the evaluation of local deterioration remains complex. In order to overcome such problems, it is necessary to combine macroscopic methods with local methods.

Fraunhofer IZFP has provided a robust solution for a local cutting edge evaluation, based on four local micromagnetic methods: harmonic analysis, Barkhausen noise, incremental permeability and eddy current. To improve this correlation between measuring results and mechanical properties is investigated via a robust finite element code by studying the magnetic behaviour of electrical steel. A more comfortable computation methodology is integrated in order to manage the memory space and convergence problems using separated calculation. The ferromagnetic material behaviour in quasi-static domain is described by the analytical hysteresis formula of Jiles-Atherton. The classical and excess losses are represented by the Berttoti model formula. The complete system: 3MA NDT device and FeSi 3% material are simulated via Flux FEM software (development version). First validations are performed by comparing simulated signatures to experimental ones in similar conditions. The cutting edge is evaluated by comparing three different cutting tool conditions: sharp, medium and blunt. Macroscopic and microscopic magnetic parameters will be correlated to the the tool condition.