Time-frequency and Time-Scale analysis of Barkhausen noise signals

Carrying out information about the microstructure and stress behaviour of ferromagnetic steels, Magnetic Barkhausen Noise (MBN) has been used as a basis for effective Non Destructive Testing methods, opening new areas in industrial applications. One of the factors that determines the quality and reliability of the MBN analysis is the way information is extracted from the signal. Commonly, simple scalar parameters are used to characterize the information content, such as amplitude maxima and signal root mean square. This paper presents a new approach based on the timefrequency analysis. The experimental test case relates the use of MBN signals to characterize hardness gradients in a AISI4140 steel. To that purpose are assessed different time-frequency and time scale representations such as the spectrogram, the Wigner-Ville distribution, the Capongram, the ARgram obtained from an AutoRegressive model, the scalogram, and the Mellingram obtained from a Mellin transform. It is shown that, due to non-stationary characteristics of the MBN, timeha l-0 03 58 87 5, v er si on 1 4 Fe b 20 09 Author manuscript, published in "Proceedings of the Institution of Mechanical Engineers. Part G, Journal of Aerospace Engineering 223, 5 (2009) 577-588" DOI : 10.1243/09544100JAERO436