PSI - Issue 25

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ScienceDirect

Procedia Structural Integrity 25 (2020) 195–200 Structural Integrity Procedia 00 (2019) 000–000 Structural Integrity Procedia 00 (2019) 0–000

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the VCSI1 organizers Abstract In the present study, a series of uniaxial compression and three-point bending experiments of marble and cement mortar specimens were carried out under different loading rates until fracture, using specimens of different geometries. During the tests the acoustic activity produced was recorded and as a next step, the energy of the acoustic signals was analysed in natural time. As a result, the variance κ 1 of the natural time analysis of the acoustic energy was proven to exhibit an exponential tail as previously found for the order parameter in several equilibrium or non-equilibrium systems.The findings presented here support the use of the κ 1 as an order parameter for the acoustic emission events in the last seconds before the failure of the specimens. © 2020 The Authors. Published by Elsevier B.V. is is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) r-review line: Peer-review under respo sibility of the VCSI1 organizers. Keywords: acoustic emissions; natural time; construction materials; order parameter 1. Introduction The Acoustic Emissions (AE) technique relies on the detection of transient elastic waves emitted due to the initiation and propagation of cracks when the material is under stress. These waves travel within the material towards the boundaries of the specimen, where they are detected by AE sensors. The AE technique is a non-destructive monitoring technique widely used for the estimation of the remaining service life and the overall integrity of structural elements or structures (Rao and Lakshmi, 2005; Holford, 2009; 1st Virtual Conference on Structural Integrity – VCSI1 Similarity of fluctuations of acoustic emissions in natural time Andronikos Loukidis a, ∗ , Ermioni D. Pasiou b , Nicholas V. Sarlis c,d , Dimos Triantis a a Electronic Devices and Materials Laboratory, Department of Electrical and Electronics Engineering, University of West Attica, 250 Thivon Avenue, 122 44, Athens, Greece b Laboratory for Testing and Materials, Department of Mechanics, National Technical University of Athens, Theocaris Building, 5 Heroes of Polytechnion Avenue, 157 73, Athens, Greece c Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos 157 84, Greece d Solid Earth Physics Institute, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos 157 84, Greece Abstract In the present study, a series of uniaxial compression and three-point bending experiments of marble and cement mortar specimens were carried out under different loading rates until fracture, using specimens of different geometries. During the tests the acoustic activity produced was recorded and as a next step, the energy of the acoustic signals was analysed in natural time. As a result, the variance κ 1 of the natural time analysis of the acoustic energy was proven to exhibit an exponential tail as previously found for the order parameter in several equilibrium or non-equilibrium systems.The findings presented here support the use of the κ 1 as an order parameter for the acoustic emission events in the last seconds before the failure of the specimens. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review line: Peer-review under responsibility of the VCSI1 organizers. Keywords: acoustic emissions; natural time; construction materials; order parameter 1. Introduction The Acoustic Emissions (AE) technique relies on the detection of transient elastic waves emitted due to the initiation and propagation of cracks when the material is under stress. These waves travel within the material towards the boundaries of the specimen, where they are detected by AE sensors. The AE technique is a non-destructive monitoring technique widely used for the estimation of the remaining service life and the overall integrity of structural elements or structures (Rao and Lakshmi, 2005; Holford, 2009; 1st Virtual Conference on Structural Integrity – VCSI1 Similarity of fluctuations of acoustic emissions in natural time Andronikos Loukidis a, ∗ , Ermioni D. Pasiou b , Nicholas V. Sarlis c,d , Dimos Triantis a a Electronic Devices and Materials Laboratory, Department of Electrical and Electronics Engineering, University of West Attica, 250 Thivon Avenue, 122 44, Athens, Greece b Laboratory for Testing and Materials, Department of Mechanics, National Technical University of Athens, Theocaris Building, 5 Heroes of Polytechnion Avenue, 157 73, Athens, Greece c Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos 157 84, Greece d Solid Earth Physics Institute, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos 157 84, Greece

∗ Corresponding author. Tel.: +306980162991 E-mail address: a.loukidis@uniwa.gr (Andronikos Loukidis). ∗ Corresponding author. Tel.: +306980162991 E-mail address: a.loukidis@uniwa.gr (Andronikos Loukidis).

2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the VCSI1 organizers 10.1016/j.prostr.2020.04.023 E-mail address: a.loukidis@uniwa.gr 2210-7843 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review line: Peer-review under responsibility of the VCSI1 organizers. E-mail address: a.loukidis@uniwa.gr 2210-7843 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review line: Peer-review under responsibility of the VCSI1 organizers.