Adaptive testing of Materials using Preisach Model Parameters Variations - Introductory Tests
Elemir Usak, Jan Bydzovsky, Tomas Visnovec
DOI:
Abstract
A new diagnostic method (MAT - Magnetic Adaptive Testing) for non-destructive testing of ferromagnetic construction materials (i.e. iron based) under mechanical stress is under development, [1]. The method is based on the investigation of the correlation between the mechanical load and the parameters of Preisach-like model describing magnetic properties of such materials as the differential permeability matrix. To get the set of model parameters needed, a number of minor hysteresis loops under defined exciting magnetic field strength waveform shape H(t), especially with constant field change rate dH(t)/dt required (which implies the inducted voltage to be proportional to the differential permeability), is to be measured. The influence of initial magnetic state of the investigated material, algorithm of demagnetisation process, the slope of time dependence of exciting magnetic field on the signal-to-noise ratio and stability of the measured signal is discussed.