M. V. Petrov

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.

Developing an integrated technique to evaluate crack formation in reinforced concrete under uniaxial compression

Regularities of changes in the parameters of acoustic and electromagnetic emission and of forced electric response from reinforced concrete under uniaxial compression have been studied. It has been established that the main diagnostic criteria of the onset of crack formation are the emergence of high-amplitude signals of acoustic and electromagnetic emission; considerable changes in the spectral composition of the electric signal; a decrease in the maximum coefficient of correlation between the spectra of signals registered at different stages of loading as compared with the spectrum of the signal prior to loading; and hopping shift of the frequency at which the maximum correlation coefficient is observed. On-line monitoring and periodic inspection can be used to assess the onset of crack-formation processes.

A Method for Evaluating Failure in Reinforced Concrete under Bending Based on the Response of Electrical Parameters to an Impact Action

The regularities of changes in the properties of the electrical response of reinforced concrete to an impact action in a four-point bending flexural test and the influence of the rebar cage configuration on the processes of failure in reinforced beams and on electrical response parameters have been studied. Criteria have been proposed for determining the stages of failure in reinforced concrete beams, based on electrical response parameters. The nucleation and growth of macrocracks in the tensile zones of reinforced beams is accompanied by a drop in the maximum cross-correlation coefficient of signal spectra at the current and previous loading levels to 0.45–0.6. An increase in the energy attenuation coefficient of electrical responses in a reinforced beam by 1.5–2.5 times can serve as a precursor to its impending catastrophic breakdown.

The Relationship Between the Parameters of the Electric and the Acoustic Signal with the Destruction of Concrete Under Cyclic Freeze-Thaw

The paper presents the research results of the effect of formation crack process on the parameters of the electric and acoustic response to impact excitation. The physical basis of mechanoelectric transformations is described. It was found that with increasing number of freeze-thaw cycles observed increase of the attenuation coefficient of energy of the electric and acoustic response by a linear relationship. Differences in the dynamics of change of attenuation coefficient of energy of the electric and acoustic response associated with differences in formation and registration of electric and acoustic response.

Influence of cyclic freeze-thaw on the parameters of the electric response to the pulse mechanical excitation of concrete reinforced by glass fibre reinforced polymer bars

Studies of the influence of cyclic freeze-thaw on the parameters of electric response from samples of concrete reinforced by glass fibre reinforced polymer (GFRP) bars were conducted. It is found that an increase in the number of freeze-thaw cycles increases the attenuation coefficient of energy of electric responses and moves the centre of gravity of spectrum to the low-frequency area. The results can be used to develop a method of nondestructive testing of reinforced concrete.