A Study of Fracture Scenarios on the Basis of Acoustic Emission Data

A system of equations for studying the fracture of solids has been formulated using a physico-mathematical model that describes the heat and mass transfer in heterogeneous media. The derived relations are used to analyze the energy balance equation and to study the fracture of a concrete sample under uniaxial compression. The analysis is performed by a quantitative interpretation of experimental data on two acoustic emission amplitude and frequency spectra recorded during sample loading. The spectra provided data on the time evolution of the structural characteristics of the material and were used to evaluate the relationship between the rates of change of surface energy and acoustic emission intensity per unit volume of the compressed concrete sample at the time of recording the spectra. Conditions for the occurrence of possible fracture scenarios by the time of recording the second spectrum were investigated. With experimental data on acoustic emission amplitude-frequency spectra for more than two time points, it is possible to study in more detail the changes in the structural characteristics, surface energy, and acoustic emission intensity per unit volume of a solid. The beginning of particular fracture stages can be predicted with higher accuracy.