No abstract

The potentialities of the pressure stimulated currents technique to be used as a continuous structural health monitoring tool in applications related to stone monuments are assessed experimentally. The data gathered by this technique from experiments with notched marble plates submitted to direct tension are considered in juxtaposition to the respective ones provided by the acoustic emissions technique, a well‐founded and widely used sensing tool. The time evolution of the pressure stimulated currents produced provides clearly distinguishable fingerprints of upcoming fracture well before visible cracking is macroscopically observed. These fingerprints are in good qualitative agreement with similar ones provided by the acoustic emissions, and therefore, they can be considered as safe prefailure indicators designating entrance to a “critical stage.” Thus, the use of the pressure stimulated currents technique as an alternative structural health monitoring system appears quite promising, taking also into account the low cost and the small size of the respective sensors.

No abstract

No abstract

The efficiency of two modern sensing techniques, namely the "Acoustic Emissions" and the "Pressure Stimulated Currents" ones, when they are used as Continuous Structural Health Monitoring tools, is assessed experimentally. The protocol includes multi-point bending of an accurate copy of a fractured marble epistyle of the Parthenon's Temple on the Acropolis of Athens, under a scale of 1:3. The integrity of the epistyle is restored with three pairs of bolted titanium bars, according to the pioneering technique developed by the scientists of the "Committee for the Conservation of the Acropolis Monuments". The data provided by the above techniques are considered in juxtaposition to each other and also in comparison to data provided by the "Digital Image Correlation" technique. It is concluded that, at least from a qualitative point of view, the data of all three techniques are in good mutual agreement. Combined exploitation of the various sets of experimental data enlightens interesting aspects concerning the succession of failure mechanisms activated during the loading procedure, revealing the critical role of the internal interfaces characterizing the restored epistyle. Moreover it is definitely indicated that both the "Acoustic Emissions" and the "Pressure Stimulated Currents" techniques provide clear signs of upcoming failure well before macroscopically visible damages are detected at the external surface of the specimen.