Exploring the acoustic activity in brittle materials in terms of the position of the acoustic sources and the power of the acoustic signals—Part I: Founding the approach

Abstract

The acoustic activity in brittle specimens submitted to mechanical loading is explored in terms of two alternative approaches. The first one is based on the Euclidean three-dimensional distance between the sources of successive acoustic events while the second is based on the power of the acoustic signals recorded. In the direction of quantifying the acoustic activity according to these alternative approaches two functions are introduced, the time evolution of which is considered in juxtaposition to that of the externally applied mechanical load and the respective one of a previously introduced function, namely, the F-function. The latter is determined by taking advantage of the interevent time intervals between successive acoustic signals. Data gathered during an experimental protocol, with notched marble plate-shaped specimens subjected to uniaxial tension, are used to outline the procedure for calculating the newly introduced functions. Analysis of the time evolution of these functions exhibits series of common qualitative characteristics with the respective one of the F-function. Moreover, it is indicated that proper interpretation of the respective data in terms of the “time-to-failure” parameter provides interesting signs that could be considered as pre-failure indices.