Mechanical response of notched marble beams under bending versus acoustic emissions and electric activity

Abstract

An experimental protocol, including the combined application of both innovative and traditional sensing techniques, is described aiming to explore the mechanical response of marble and also to check the possibilities of detecting precursor phenomena designating upcoming catastrophic fracture. The protocol consisted of three-point bending tests with notched prismatic beams made of Dionysos marble, the material extensively used for restoration of the Acropolis of Athens monuments. The sensing system improvised included techniques relying on completely different physical foundations, which permit simultaneous detection and recording of the Pressure Stimulated Currents, Acoustic Emissions, three dimensional displacement fields and Notch Mouth Opening Displacements. Analysis of the results revealed interesting features of the mechanical response of Dionysos marble and indicated, also, that classical Continuum Fracture Mechanics fails to describe accurately the response of marble, at least in the presence of notches. In addition, strong correlations between the Pressure Stimulated Currents, the rate of acoustic hits and the rate of change of the opening of the pre-existing notch have been enlightened. Moreover, the onset of catastrophic crack propagation appears following distinguishable changes of the Pressure Stimulated Currents recorded. Therefore (and taking into account the very small size of the respective sensors as well as the simple complementary equipment needed), it is concluded that the specific technique could be considered as a simple and reliable tool for an alternative approach to the in-situ Structural Health Monitoring of classical stone monuments.

Double initial and caustic curves in diametrically compressed transparent discs - Application to the contact length

“…Finally, it should be noticed that the general formulae including double and single caustics obviously refer also to opaque materials as particular cases of the transparent ones, provided their faces are properly polished. The latter could be of crucial importance, especially for specimens made of marble [50] and natural building stones [51], the mechanical response of which is usually studied using the Brazilian-disc test (due to insuperable difficulties encountered in the implementation of direct uniaxial tension tests, caused due to the unique nature of such materials [52][53][54][55][56]) employing either traditional or innovative experimental techniques [57][58][59][60].…”

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

“…From b = β × 20/ ln (10), the maximum likelihood confidence limits of the b value with a narrow amplitude span in DTFAD can be obtained using Equation (17).…”

“…Additionally, since the selection of amplitude limits of the 'linear range' of the frequencyamplitude distribution and estimation method has a great influence on the calculation of the b value, considering the mean and standard deviation of the AE amplitude sample, Shiotani proposed the parameter of the Ib value (improved b value), which is also widely used to evaluate and monitor the fracture behavior of materials. Many studies have shown that the Ib value and the b value are different in size, but the change trend is the same [8][9][10].…”

Non-Extensive Statistical Analysis of Acoustic Emissions: The Variability of Entropic Index q during Loading of Brittle Materials Until Fracture

“…The dimensions of the specimen were 20 × 20 × 100 mm 3 and the notch dimensions were 2.5 mm in width and 4 mm in length. The specimen was subjected to three-point bending under displacement-control mode at a rate of 0.01 mm/min [47]. So-called EXP-2 was conducted on a marble doubleedge notched specimen of dog-bone shape.…”