In-situ estimation of defect volume from parameters of acoustic emission signals

By using two methods of nondestructive testing, i.e., acoustic emission (AE) measurements and X-ray computed microtomography (CT), an experimental study of defect accumulation during a uniaxial compression of a natural heterogeneous material was carried out. A joint analysis of the AE and CT data revealed a correspondence between energy characteristics of the acoustic emission accompanying defect formation and volume of defects. It is shown that the dependence of the total energy of AE signals on the defect volume is linear, which is consistent with the phenomenological dependences for earthquake focuses obtained earlier. The linear dependence was used to estimate the average defect size. It is shown that, regardless of the assumed defect shape, its average linear size does not exceed 100 μm.

Структурно-энергетические закономерности накопления повреждений при деформировании гетерогенного материала

An experimental research of the defect accumulation under uniaxial loading of a natural heterogeneous material is carried out in this work. Defect formation process has been controlled using two non-destructive techniques (methods) such as acoustic emission (AE) and X-ray computed microtomography (CT). The combined use of these methods made it possible to find out correspondence between energy characteristics of AE accompanying the defect formation and the volume of these defects. It was found that total defect volume is lineary dependent on total AE signal energy. This fact corresponds to previously discovered phenomenological relationships for the sources of tectonic earthquakes. Mean defect size has been estimated based on obtained linear dependence. It was shown that mean linear size of defect does not exceed 100μm regardless of the assumptions about the defect shape.