PSI - Issue 18

Prokhorov A. et al. / Procedia Structural Integrity 18 (2019) 802–808 Author name / Structural Integrity Procedia 00 (2019) 000–000

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transformer core, the occurrence of discontinuities in the sample in the form of a rupture or accumulation of pores should lead to the occurrence of discontinuities in the signal of the secondary winding, the inductance located on the sample.

Fig. 3. The scheme of testing in an external magnetic field.

4. VHCF test result The signal detected on inductance coil consists of from induced signal by magnetic field and the specimen oscillation due to applied mechanical cyclic loading. This signal can be considered as modulation mechanical oscillation by induced field. The discrete Fourier transform of registered signal shown expected maximums of spectrum on 700 Hz, 20 kHz and higher harmonics 40kHz, 60khz etc. In the figure 4 shown the part (0-1600Hz) of the spectrogram of process during the test. The noise area from the both sides of main frequency which is moves far away from it with different dynamic. Authors suppose that this Barkhausen effect, Soultan M. et al(2006). Alternating magnetic field moves the magnetic domains borders, which is initiate the low frequency oscillation in the crystal cell. This effect has an application in non-destructive control technique and applied to ferromagnetic materials. Authors suppose that the structural evolution during fatigue test changes the frequency of this oscillation which is modulate the main frequency of alternating magnetic field.

Impulse Number

Fig. 4. Spectrogram of process during the experiment.