Two-Dimensional Ray Mathematical Model of Mechanoelectric Transformations Method for Location of Macrodefects Identification in Solid Dielectric Structures

Method of mechanoelectric transformations can be applied to determine both horizontal position and the depth of a defect in solid nonconductor samples. The method is based on phenomenon of electromagnetic emission in sources of mechanoelectric transformations, such as cracks, voids and impurities of sample structure. It has been shown that method can be used to evaluate integrated stress-strain state of solid dielectric materials. The method is also capable of finding defects is the sample volume, but the robust methodology has to be developed. To develop a methodology of the proper scanning process the experimental setup was created. This work represents ray model of this setup. The model allows us to research pulse characteristics of the response signal considering a variety of excitation signal parameters, defect locations and depths. The model includes dimensions of real sample. Pulse characteristics for response signals of single-period excitation waves with 100 kHz, 300 kHz, and 600 kHz frequencies were obtained. It is shown that increasing the frequency of excitation increases the accuracy of estimating the depth of macrodefects. Time-response characteristics of the signal are most informative.

Diagnostics of Fibre-Reinforced Concrete by the Nondestructive Method Based on Mechanoelectric Transformations Phenomenon

This article presents the results of a study of the effect of crack formation in concrete that occurs during uniaxial compression on the parameters of the electrical response under periodic impulse shock action. Researches were conducted on fibre-reinforced concrete samples and samples without reinforcement. It is shown that the method based on mechanoelectric transformations phenomenon can be equally applied to both unreinforced and fibre-reinforced concrete samples.

Experimental study of mechanoelectric transformations in low saturated rocks

The results of study of the electrical response of dry and slightly saturated with salted water (NaCl) or kerosene cores of Berea sandstone to acoustic effect in the frequency range of 0.5–10 kHz are presented herein. A strong lateral inhomogeneity by saturation was created during the experiments. The electrical response is sensitive to the addition of all types of fluid in the rock samples. At the same time, the reaction to the addition of highly concentrated salt solution in the samples is weak, while the reaction to the addition of weak concentrated salt solution and kerosene is strong. A high correlation is observed between the shape of the electrical response spectra of dry and damped cores, up to 0.9. For kerosene, the shape of the spectrum varies greatly, the rank correlation coefficient of the shape of the spectra is 0.3. The fact of a significant increase in electrical response on addition of non-polar fluid (kerosene) to the core is beyond the theoretical framework and may be associated with the creation of strong lateral petrophysical heterogeneity by saturation. The strong sensitivity of the amplitude of the electroseismic response of rocks to very weak but non-homogeneous saturation is interesting for the development of remote methods for determination of the type of fluid saturation of rocks, when searching for minerals and for the development of the methods for prediction of geophysical catastrophes.