Modelling the energy balance of acoustic emission

We present a simple mesoscopic model to describe the phenomenon of Acoustic Emission (AE) in a material undergoing damage in quasistatic tests. As in all damaging processes, in AE experiments a part of the mechanical energy stored in the deforming material is dissipated due to crack formation and propagation. The present model correctly accounts for energy dissipation due to the formation of micro-cracks and the creation of surfaces in the material as damage progression advances and is thus used to derive the AE scaling behaviour observed in experiments. A simple example is chosen to illustrate typical results obtained in numerical simulations using the model, namely a 2-D specimen in the form of a concrete bar subjected to uniaxial tests. The model is then used to fit data derived from experimental tests: first, on masonry elements of various sizes tested in compression by means of double flat-jacks; secondly, on a fibre-reinforced concrete specimen subjected to three-point bending. The numerical model presented here correctly reproduces the scaling behaviour and spatial distributions of AE events observed experimentally.