Electromechanical Conversions in Composite Dielectric Materials During Complex Thermomechanical Excitation

It is shown that the degree of the stress-strain state created by temperature field can be estimated by using the electromechanical conversion phenomenon. It is established that the electromagnetic response to impact excitation of composite materials is a structure-sensitive characteristic.     

The influence of humidity on the parameters of an electric signal under pulsed mechanical excitation of heterogeneous materials containing piezoelectric inclusions

The main patterns of the influence of the moistness of heterogeneous dielectric materials that contain piezoelectric inclusions on the parameters of an electric response under their pulsed mechanical excitation were studied. The proposed physical model of mechanoelectrical transformations in a moist heterogeneous material agrees with experimental data. The results of the performed investigations are the initial data for developing an algorithm for nondestructive mechanoelectrical testing of the strength of heterogeneous materials that contain piezoelectric inclusions under changes in their moistness.     

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.     

Electromagnetic diagnostics of composite materials

It was studied the main regularities of mechanoelctric transformations in composites and developed electromagnetic methods of control of quality.     

Evaluating the depth of open cracks in concrete from parameters of electric response to elastic-impact excitation

We have studied the character of decay of the spectral components of electric response to elastic impact excitation of a concrete sample with artificial cracks of various depths. A criterion for determining the depth of surface cracks in concrete is proposed based on results of time-frequency analysis of the response signal.     

The relationship of the structural characteristics of concrete with the parameters of the electrical response upon elastic impact excitation

The effect of the composition of a coarse aggregate on the parameters of the electrical response under elastic impact excitation of samples of heavy concrete and structural claydite-concrete is investigated. The aggregate composition is shown to affect the elasto-plastic properties of concrete and its strength and to result in a change in the value and spectral composition of the electric response.     

On the relationship between the parameters of the electric response to pulsed mechanical exposure and the formation of cracks in concrete

The relationship between the parameters of acoustic emissions and the electric response to pulsed mechanical excitation of high-density concrete and the stages of deflected mode that is formed by external compressive loadings was studied. It was established that the attenuation coefficient of the electric-response energy increases considerably when a concrete sample passes from elastic deformation into the fracturing zone.     

Electron-impact excitation and ionization cross sections for ground state and excited helium atoms

Comprehensive and critically assessed cross sections for the electron-impact excitation and ionization of ground state and excited helium atoms are presented. All states (atomic terms) with n4 are treated individually, while the states with n5 are considered degenerate. For the processes involving transitions to and from n5 levels, suitable cross section scaling relations are presented. For a large number of transitions, from both ground and excited states, convergent close coupling calculations were performed to achieve a high accuracy of the data. The evaluated/recommended cross section data are presented by analytic fit functions, which preserve the correct asymptotic behavior of the cross sections. The cross sections are also displayed in graphical form.     

Electromagnetic Nondestructive Method of Testing the Runway Quality

A new method of testing the runway quality on the basis of parameters of the electromagnetic response to an impact excitation is proposed.