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2 Poznan University of Technology Academic Journals. Electrical Engineering

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An attempt to appraise the progress of methyl polymethacrylate degradation induced by a strong electric field on the grounds of analysis of acoustic signal emission

Dobrzycki A., Opydo W.

Poznan University of Technology Academic Journals. Electrical Engineering

2007

No 56

197-203

The paper presents the research of methyl polymethacrylate treeing in a strong electric field. The treeing rate and the signals of acoustic emission have been subject to the research. The counting rate of the acoustic emission, the rate of acoustic emission events, and rms signal have been used as parameters of acoustic emission signals. It was found that high increase in the rate of methyl polymethacrylate treeing is accompanied by the growth of counting and events rates of emitted acoustic signals. On the other hand, no correlation between the values of the above mentioned descriptors and the rms signal values has been observed in measured acoustic signals.

Computer-aided analysis of acoustic emission signals accompanying methyl polymetacrylate degradation in a strong electric field

Dobrzycki A., Opydo W., Dobroszewski R.

Poznan University of Technology Academic Journals. Electrical Engineering

2006

No 52

201-210

The paper presents the results of frequency and time-frequency analyses of the acoustic emission signals arising during degradation of methyl polymetacrylate in a strong electric field. The frequency analysis was carried out with the use of Fourier Fast Transform method (FFT), while the time-frequency analysis - with the use of Short-Term Fourier Transform (STFT). The MatLafa software package was used for purposes of analyzing. It was found that the acoustic emission signals measured this way include some predominant frequencies. Results of the studies have shown that in the considered frequency range of the acoustic emission signals (0÷96kHz) the part of the signals of frequencies CH-15kHz and 43÷53kHz predominated.