Simulation of Flaw Signals in a Magnetic Flux Leakage Inspection Procedure

O. Nemitz, and T. Schmitte
Salzgitter Mannesmann Forschung GmbH, Duisburg, Germany
Published in 2010

In the inspection of steel products with respect to flaws a magnetic flux leakage (MFL) test procedure can be applied. In this procedure a “horseshoe” shaped yoke is used, whose legs are wrapped with coils through which an alternate current with a high frequency (3 kHz) is flowing. Hereby a thin magnetic field is induced near the surface of the test object which leaks from the material if a flaw is present. The aim of the simulation using COMSOL is to find out how different flaw geometries and orientations influence the measured signal. In a first step we simulated a 2D-cross-section and varied width, depth and orientation of the notch. In a second step 3D-simulations were performed. The computation on a fully meshed geometry was only possible with a swept mesh and the use of symmetries. Hereby the complete 3D-model could be simulated and arbitrary notches could be modelled.