PSI - Issue 13

Ekaterina Damaskinskaya et al. / Procedia Structural Integrity 13 (2018) 298–303 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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As long as the load was lower than 0.9 of the breaking one (the first 9 stages of loading), a relatively small number of AE signals (dozens) was recorded. At the last two stages the number of signals increased by 2 orders of magnitude. Let us dwell on the analysis of the acoustic emission data obtained at the last stage of loading. The distribution of the number of AE signals along the sample height (Fig. 2, curve) exhibits a pronounced region characterized by the largest number of generated AE signals as compared with other regions of the sample. This region is also characterized by the signals with the highest energy (Fig. 2, squares).

Fig. 2. Acoustic emission (final stage of loading). Distribution of number of AE signals along the sample height and energy of AE signals (squares).

The energy distribution of AE signals was analyzed separately for the signals detected from the upper and lower parts of the sample. Figure 3 shows the energy distribution of the signals recorded from the upper half of the sample (Region I). The energy distributions of these AE signals can be approximated by a power-law or exponential function with nearly equal coefficients of determination R 2 . This is illustrated in Fig. 3, in which this distribution is plotted in double logarithmic (Fig. 3a) and semi-logarithmic (Fig. 3b) coordinates (a similar picture was observed in other experiments) [Damaskinskaya et al. (2017)]). According to our hypothesis, this means that this region of the sample material is at a non-dangerous stage of defect accumulation.

Fig. 3. Energy distribution of AE signals in the sample region labeled "Region I" (R 2 is the coefficient of determination).