The Analysis of High Sensitivity Time-Frequency Spectral Parameters in Magnetic Barkhausen Noise for the Characterization of Mechanical Properties

The safety aspects of key components made from ferromagnetic materials are directly influenced by stress and hardness, thus necessitating the detection and evaluation of material hardness and stress state in the applications of such materials. This study proposes a highly sensitive method for characterizing mechanical properties (stress and hardness) using the time-frequency information of magnetic Barkhausen noise (MBN) technique. The MBN amplitude spectrum is obtained using the Short Time Fourier Transform (STFT) method under various mechanical conditions. The relationship between the amplitude spectrum and stress (or hardness) is analyzed in a point-by-point manner within the spectrums. A linear equation is employed to fit the dependence of mechanical property on the amplitude spectrum. Subsequently, the slope of the linearized equation is calculated to construct a sensitivity matrix. The optimal region is selected based on the amplitude spectrum region exhibiting high sensitivity. Goodness of fit, rate of change, and absolute error are employed as indicators to assess the parameters' capability in characterizing mechanical properties. This study compares the time-frequency domain parameters obtained through the proposed methodology with the conventional time-domain parameters. Time-frequency information of MBN could play a valuable role for the non-destructive evaluation of mechanical properties.