PSI - Issue 33

Dimos Triantis et al. / Procedia Structural Integrity 33 (2021) 330–336 Dimos Triantis et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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Fig. 7. The electric activity, at the stage of impending fracture, in terms of the PSC recorded, for a characteristic specimen with a 0 =6 cm.

Fig. 8. The F-function in terms of the “ time-to- fracture” parameter ( τ t f ) for a specimen with a 0 =6 cm (pay attention that τ is an average time).

5. Concluding remarks The acoustic activity in notched marble specimens under uniaxial tension at the last loading stages before fracture was studied in juxtaposition to the respective electric activity quantified in terms of the Pressure Stimulated Currents. It was concluded that the acoustic activity during this time interval is excellently described by a power law, inde pendently of whether it is explored in terms of the cumulative counts or the F-function. A similar law describes, also, the electric activity during the same time-interval. The power law appears governing earlier the response of the notch from which fracture starts. Assuming that the onset of validity of the power law is a pre-failure index, it can be said that, prediction of the entrance into the “critical stage” of Dionysos marble is possible using either the AE or the PSC technique. In spite of the relatively low scattering of the experimental data of the present study, additional protocols with a much broader variety of loading schemes and materials are required, in order for the conclusions of this study to be better founded and, also, for the data of the AE- and PSC-techniques to be quantitatively correlated to each other. References Niu, Y., Zhou, X.P., Zhou, L.S., 2019. Fracture damage prediction in fissured red sandstone under uniaxial compression: acoustic emission b-value analysis. Fatigue and Fracture of Engineering Materials and Structures 43, 175–190. Sharma, S.K., Chauhan, V.S., Sinapius, M., 2021. A review on deformation-induced electromagnetic radiation detection: history and current status of the technique. Journal of Materials Science 56, 4500–455. Stavrakas, I., Triantis, D., Agioutantis, Z., Maurigiannakis, S., Saltas, V., Vallianatos, F., Clarke, M., 2004. Pressure stimulated currents in rocks and their correlation with mechanical properties. Natural Hazards and Earth System Sciences 4, 563–567. Triantis, D., Kourkoulis, S.K., 2018. An alternative approach for representing the data provided by the acoustic emission technique. Rock Mechanics and Rock Engineering 51, 2433–2438 Triantis, D., Pasiou, E.D., Stavrakas, I., Kourkoulis, S.K., 2021. Hidden affinities between electric and acoustic activity in brittle materials at near fracture load levels (to appear). Varotsos, P.A., Sarlis, N.V., Skordas, E.S., 2002. Long-range correlations in the electric signals that precede rupture. Physical Reviews E 66:011902. Wang, X., Wang, E., Liu, X., 2019. Damage characterization of concrete under multi-step loading by integrated ultrasonic and acoustic emission techniques. Construction and Building Materials 221, 678–690. Zhang, J.Z, Zhou, X.P., Zhou, L.S., Berto, F., 2019. Progressive failure of brittle rocks with non-isometric flaws: Insights from acousto- optic‐ mechanical (AOM) data. Fatigue and Fracture of Engineering Materials and Structures 42, 1787–1802.