T. V. Fursa

Development of a nondestructive method for testing the strength of concrete with a faulted structure based on the phenomenon of mechanoelectric transformations

An algorithm for nondestructive testing of concrete strength based on the parameters of an electric response to elastic impact excitation has been developed based on experimental studies. The error in determining the strength using the proposed algorithm is 9% for heavy-weight concrete.

Development of an acoustoelectric method for determining the porosity of dielectric materials

The regularities of acoustoelectric transformations in cement stones with different water-to-cement ratios are studied. A physically substantiated acoustoelectric method for determining the porosity of dielectric materials is proposed.

The development of a method for crack-depth estimation in concrete by the electric response parameters to pulse mechanical excitation

A method is proposed for contactless testing of cracks in concrete by the electric response parameters to pulse mechanical excitation. Theoretical research is conducted on the electric response to pulsed elastic impact of the material with piezoelectric quartz inclusions. Numerical results are confirmed by experimental research on concrete samples. It is shown that the presence and growth of a crack in concrete lead to a change in measured electrical signal frequency response. Increase in crack depth leads to a shift of dominant spectral peaks to the lower-frequency region and decreases the cross-correlation coefficient between spectra from the sample containing defects and a solid sample.

Relation between the electric response and the characteristics of elastic waves under shock excitation of heterogeneous dielectric materials with piezoelectric inclusions

A physicomathematical model is proposed for the electric response to elastic shock excitation of piezo-containing heterogeneous materials. The parameters of the electric signal under a pulsed action on a dielectric sample containing a piezoelectric inclusion are calculated theoretically using the apparatus of the mechanics of continuous media, and the conformity to experimental results is observed.

Interrelation between electromagnetic response parameters and impact excitation characteristics in insulators

The effect of the impact energy and duration on the parameters of the electromagnetic response from concrete is studied. These two parameters are shown to affect the spectral characteristics of the response. The duration of the first pulse of the response reflects the duration of the impact excitation active stage. An impact excitation energy above 5×10−2 J causes irreversible residual strains in concrete.

Developing a method based on mechanoelectric transformation for monitoring concrete defectness variation under influence of freezing-thawing cycles

It is shown that the increasing defectness (cracking) of concrete under the influence of multiply repeated freezing-thawing cycles leads to a definite transformation of the spectral characteristics of the electric signal generated in the material in response to mechanical impact pulses. It is suggested that the maximum coefficient of mutual correlation between the spectrum of the electric response signal of a defect material and that of an intact sample can be used as a criterion for evaluating the extent of cracking (total crack length) in concrete and monitoring its variation.

Peculiarities of the mechanoelectrical response in dielectric materials in the region of structural phase transformations

The influence of thermally induced structural phase transformations on the electromagnetic response of gypsum upon impact excitation is investigated. It is found that the electromagnetic response upon impact excitation is the structure-sensitive characteristics of dielectric materials. Data on the character of phase transformations in gypsum heated above 150°C are obtained using X-ray diffraction techniques.

Development prospects for nondestructive testing of heterogeneous nonmetallic materials by the parameters of electrical response to a shock action

Theoretical and experimental research has been conducted into the mechanisms of generation of electric fields under elastic shock excitation of heterogeneous nonmetallic materials that contain two types of mechanoelectric transductions, viz., double electrical layers at interphase boundaries and piezoelectric inclusions. Using the example of electrical responses from samples of heavy- and light-weight concretes and based on numerical modeling results, prospects are shown for using this phenomenon in nondestructive testing of heterogeneous nonmetallic materials that do not contain piezoelectric inclusions, e.g., layered and reinforced ones.

Effect of cyclic freezing–thawing on the parameters of electric response to elastic shock excitation of reinforced concrete

General and distinctive features have been established for the effect that cyclic freezing–thawing has on the parameters of electric response to elastic shock excitation in steel and glass-fiber reinforced concretes. Based on frequency-time and autocorrelation analyses, criteria are suggested for assessing the deterioration degree of reinforced concrete under alternating-sign temperature action.

Mechanoelectric transformations in cement-sand composites under the action of cyclic alternating-sign temperature variations

It is established that a change in the strength of porous composite materials under the action of cyclic alternating-sign temperature variations leads to a high-frequency shift in the center-of-gravity of the amplitude-frequency characteristics of the electric response of samples to a pulsed impact excitation.