Comparative Assessment of Criticality Indices Extracted from Acoustic and Electrical Signals Detected in Marble Specimens

Abstract

The quantitative determination of the current load carrying capability of already loaded structural elements and the possibility to detect proper indices that could be considered as signals for timely warning that the load carrying capacity is exhausted is the subject of this study. More specifically, it aims to explore the possibility of detecting signals that can be considered as indices warning about upcoming fracture and then to compare quantitatively such signals provided by different techniques. The novelty of the present study lies exactly in this quantitative comparison of the pre-failure signals provided by various sensing techniques and various methods of analysis of the experimental data. To achieve this target, advantage is taken of data concerning the acoustic and electrical activities produced while marble specimens are subjected to mechanical loading. The respective signals are detected and recorded by means of the acoustic emissions technique and that of the pressure stimulated currents. The signals detected by the acoustic emissions technique are analyzed in terms of three formulations, i.e., the b-value, the F-function and the parameters variance κ1, entropy S and entropy under time reversal S_ according to the natural time analysis. The signals detected by the pressure stimulated currents technique are analyzed by means of the intensity of the electric current recorded. The study indicates that all quantities considered provide promising pre-failure indicators. Furthermore, when the specimen is subjected to near-to-failure load levels, the temporal evolution of three of the quantities studied (b-value, F-function, pressure stimulated currents) is governed by a specific power law. The onset of validity of this law designates some differentiation of the damage mechanisms activated. Quantitative differences are observed between the time instants at which this power law starts dictating the evolution of the above parameters, indicating the imperative need for further investigation, despite the quite encouraging results of the present study.

Research on Maximum Likelihood b Value and Confidence Limits Estimation in Doubly Truncated Apparent Frequency–Amplitude Distribution in Rock Acoustic Emission Tests

“…The composition of the mineral particles of granite is complex; there are obvious cracks between the particles, which are prone to large-scale block slippage under the action of external loads, so the b value of granite is smaller than that of marble and red sandstone. The above analysis and the b-value estimation results are consistent with other studies; the brittleness of granite is greater than that of marble and red sandstone in the tests, and more high-energy-level AE events are generated during the failure process [46][47][48][49]. Additionally, although the calcite particles that make up limestone are more tightly coupled than red sandstone, there are more large-scale bedding planes inside, resulting in more large-scale damage, resulting in the smallest b value.…”

Spatial Characterization of Single-Cracked Space Based on Microcrack Distribution in Sandstone Failure

“…It is known that the original openings inside the rock are dislocated under loading, and the released energy during rupture propagates through the rock in the form of elastic waves, monitored as AE [8]. It has been widely used in rock mechanics and engineering for damage assessment and hazard warning [9][10][11].…”

Analysis of Acoustic Emission Activity during Progressive Failure in Heterogeneous Materials: Experimental and Numerical Investigation

“…Relevant examples of this method's usefulness appear in a large variety of fields. For specific applications in the analysis of AE signals, see [26][27][28][29].…”