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Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/35393

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Зараз показуємо 1 - 10 з 28

Increasing the efficiency of the surface-mounted ultrasonic electromagnetic-acoustic transducer on account of the magnetic field source
(Інститут електродинаміки НАН України, 2023) Suchkov, G. M.; Bolyukh, V. F.; Kocherga, A. I.; Mygushchenko, R. P.; Kropachek, O. Yu.
Model studies were carried out using the COMSOL Multiphysics package, aimed at ensuring the forming of a permanent magnet magnetic field at a considerable distance to a ferromagnetic product from its pole, which is necessary to create efficient portable ultrasonic electromagnetic-acoustic transducers of thickness gauges and testing and diagnostic devices. It is theoretically shown and experimentally confirmed that for portable measuring ultrasonic devices it is expedient to set the height of the permanent magnet at about 60 mm and the cross section of the magnet pole 50x50 mm2. At the same time, with a gap between the magnet pole and the product of about 30 mm, the value of the normal component of the magnetic field induction near the surface of the object is about 0.3...0.4 T, which is sufficient for thickness gauging or diagnostics of ferromagnetic products using the ultrasonic pitch-and catch method.
Metrological study of the effect of temperature on the dissociation of acetic acid
(Національний технічний університет "Харківський політехнічний інститут", 2023) Mygushchenko, R. P.; Volobuyev, M. M.; Asieieva, I. V.; Kropachek, O. Yu.; Baliev, V. M.
This article is devoted to the study of the dissociation reaction of acetic acid at a temperature change in the range from room (20 °C) to 75 °C. In the course of research, the methods were considered, the classification of the considered methods was carried out, and the methodology of the experiments was formulated. The selected technique reflects the express measurement of the hydrogen pH indicator using a portable pH-meter. Experiments were carried out in laboratory conditions – Lincoln Park, Chicago, USA. Acetic acid with a concentration of 6 mol/l was chosen as the basis. By adding a distilled water, a base concentration of 1 mol/l was obtained. Nodal temperature points were selected for measurements (four points in the temperature range of 20 °C – 75 °C); five experimental samples of acetic acid (1 mol/l) were formed; the analysis of the measurement results at nodal points was carried out for the accuracy of the measurement results of five test samples of acetic acid using first- and second-order statistical moments (mathematical expectation and variance); accuracy characteristics of experimental data (instrumental and methodical errors) were estimated. Research samples (acetic acid samples) were brought to the nodal points with a positive temperature gradient using a steam bath. The measurement error estimate was determined by the accuracy class of the device and was 0.1%. The obtained pH values were converted to the number of hydrogen cations, followed by the determination of the degree of dissociation and the dissociation constant. These determinations were carried out under the condition of ensuring chemical equilibrium. The nature of the behavior of the degree and constant of dissociation when the temperature of the test samples changes is clearly non-linear. In the course of research, the main measurement errors were established, the main of which is the nonlinearity of the transformation. Quantitative values of nonlinearity errors were determined by the method of measurements with multiple observations using the Student's correction factor. The article provides conclusions based on the results of research and presents the prospects for temperature correction of pH-meters to eliminate the temperature component of the error of pH-meters.
Minimization of errors in discrete wavelet filtering of signals during ultrasonic measurements and testing
(Національний науковий центр "Інститут метрології", 2021) Taranenko, Yu.; Mygushchenko, R. P.; Kropachek, O. Yu.; Suchkov, G. M.; Plesnetsov, Yu.
Error minimizing methods for discrete wavelet filtering of ultrasonic meter signals are considered. For this purpose, special model signals containing various measuring pulses are generated. The psi function of the Daubechies 28 wavelet is used to generate the pulses. Noise is added to the generated pulses. A comparative analysis of the two filtering algorithms is performed. The first algorithm is to limit the amount of detail of the wavelet decomposition coefficients in relation to signal interference. The minimum value of the root mean square error of wavelet decomposition signal deviation which is restored at each level from the initial signal without noise is determined. The second algorithm uses a separate threshold for each level of wavelet decomposition to limit the magnitude of the detail coefficients that are proportional to the standard deviation. Like in the first algorithm, the task is to determine the level of wavelet decomposition at which the minimum standard error is achieved. A feature of both algorithms is an expanded base of discrete wavelets ‒ families of Biorthogonal, Coiflet, Daubechies, Discrete Meyer, Haar, Reverse Biorthogonal, Symlets (106 in total) and threshold functions garotte, garrote, greater, hard, less, soft (6 in total). The model function uses random variables in both algorithms, so the averaging base is used to obtain stable results. Given features of algorithm construction allowed to reveal efficiency of ultrasonic signal filtering on the first algorithm presented in the form of oscilloscopic images. The use of a separate threshold for limiting the number of detail coefficients for each level of discrete wavelet decomposition using the given wavelet base and threshold functions has reduced the filtering error.
Еlectromagnetic-acoustic transducers for ultrasonic measurements, control and diagnostic of metal products
(Національний науковий центр "Інститут метрології", 2019) Salam, Bussi; Suchkov, G. M.; Mygushchenko, R. P.; Kropachek, O. Yu.; Plesnetsov, S. Yu.
An effective type of ultrasonic method is the electromagnetic-acoustic method, especially in determining the quality of ferromagnetic products. The main factor determining the efficiency of using electromagnetic-acoustic transducers is the magnitude of the induction of a polarizing magnetic field, which is determined by the source. The studies carried out in the framework of this activity were aimed at solving the problems of high-quality measuring testing of metal products from ferromagnetic materials by electromagnetic-acoustic transducers. The requirements are formulated for a pulsed source of a polarizing magnetic field, inductors, and core as part of electromagnetic-acoustic transducers. Taking into account the requirements, structural solutions have been proposed for constructing electromagnetic-acoustic transducers with a flat two-window inductor and a flat high-frequency inductor. Experimental studies aimed at improving ultrasonic electromagnetic-acoustic transducers with pulsed magnetic field sources have been performed. The possibility of providing the sensitivity of new transducers with thickness measurement, measuring control and diagnostics is shown. Technical solutions are proposed that reduce the effect on ultrasonic pulses of the received Barkhausen noise and coherent interference from the magnetostrictive conversion of electromagnetic energy into ultrasonic. The efficiency of using electromagnetic-acoustic transducers with a pulsed polarizing magnetic field is shown for measuring quality control of ferromagnetic products made by rolling, stamping and the like.
Simulation of Electromagnetic Conversion Process Under Torsion Waves Excitation
(Інститут електродинаміки НАН України, 2018) Plesnetsov, S. Yu.; Petrishchev, O. N.; Mygushchenko, R. P.; Suchkov, G. M.
Mathematical simulation and calculation of electromagnetic fields in the electromagnetic-acoustic transducer of rational design are performed under non-dispersive torsional waves excitation in tubular electrically conductive ferromagnetic hollow rods of small diameter, taking into account spatial, frequency, energy and material factors. The results of the research can be used to simulate and construct exciting EMATs for measuring, monitoring, and diagnostic equipment in the energy, nuclear, chemical and other industries in view of ultrasonic studies of ferromagnetic tubular products.
Simulation of Electromagnetic Conversion Process Under Torsion Waves Excitation
(Інститут електродинаміки НАН України, 2018) Plesnetsov, S. Yu.; Petrishchev, O. N.; Mygushchenko, R. P.; Suchkov, G. M.
Mathematical modeling of the electromagnetic-acoustic transducer (EMAT) for excitation of nondispersive torsional waves in tubular electrically conductive ferromagnetic hollow rods of small diameter is performed taking into account all the factors that determine the design of the EMAT. The solutions of the differential equation for the values of the electromagnetic fields formed by the high-frequency coil of the device in the gap between the transducer and the tubular ferromagnetic product are found. The results of the research can be used to simulate and design exciting EMATs for measuring, monitoring, and diagnostics in the energy, nuclear, chemical and other industries for ultrasonic test of ferromagnetic tubular products.
Reliability of the Rubber Tube of Automotive Hydraulic Braking System Under Fatigue Failures Considering Random Variation of Load and the Process of Aging of Material
(Islamic Azad University, Iran, 2019) Larin, O. O.; Potopalska, K. E.; Mygushchenko, R. P.
This paper presents the approach for the assessing of the operational reliability of a multi-layer thick-walled tube made of rubber with textile reinforcement. The analysis of the fatigue accumulation process is carried out within the framework of the concept of the continuum mechanics of damage. The mathematical model, which takes into account the accumulation of damages in case of a random spread of the strength characteristics of the material, as well as the process of stochastic aging for the elastomeric matrix of the composite and possible random variation of the workload has been developed. In this case, the aging process is modelled as a reduction of the endurance limit of the material. In this paper, the mean equivalent strains of the tube and their possible statistical variation in operation have been investigated on the basis of the finite element method. To solve the above problems, a submodeling method has been employed in this work. The probability of non-failure operation of the tube has been determined using the methods and models proposed. The influence of the rate of the aging process on the lifetime of the tube has been estimated.
Statistical Estimation of Residual Strength and Reliability of Corroded Pipeline Elbow Part Based on a Direct FE-Simulations
(Serbian Society for Computational Mechanics, 2018) Larin, O. O.; Potopalska, K. E.; Mygushchenko, R. P.
In this paper, the assessment of the effect of a corrosion defect, which is developing over time on the working capacity of the pipeline elbow, has been carried out. Corrosion damage models explicitly as volumetric defect on the out surface of the pipeline elbow. The zones on the damaged section of the pipeline on which the maximum stresses are localized has been defined using the finite element analysis. The estimation of the characteristics of the deformed state of a design with defect is analysed with the framework of computer simulations. On the basis of the obtained results, the probabilistic characteristics of the stresses and plastic strains have been approximated as a function of internal pressure and corrosion defect depth, such as mean value, coefficients of variation and asymmetry. Probability densities function of plasticity appearance have been found for different defect size in operation at typical loading levels.
Structure and Properties of Vacuum-arc Coatings of Chromium and Its Nitrides Obtained under the Action of Constant and Pulse High-voltage Bias Potential
(Sumy State University, 2017) Sobol, O. V.; Postelnyk, A. A.; Mygushchenko, R. P.; Al-Qawabeha, Ubeidulla F.; Tabaza, Taha A.; Al-Qawabah, Safwan M.; Gorban, V. F.; Stolbovoy, V. A.
To reveal the regularities of structural engineering of vacuum-arc coatings based on chromium and its nitrides, the influence of the main physicotechnological factors (the pressure of the nitrogen atmosphere and the bias potential) in the formation of coatings was studied. It was discovered that during the deposition of chromium coatings the formation of the texture axis [100], as well as the macrodeformation of compression is happening. The supply of a high-voltage negative pulse potential to the substrate increases the mobility of the deposited atoms and leads to relaxation of the compression deformation. As the pressure increases from Torr, the phase composition of the coatings changes: Cr (JCPDS 06-0694) → Cr2N(JCPDS 35-0803) → CrN(JCPDS 11-0065). The supply of high-voltage pulses leads to the formation of a texture of crystallites with parallel growth surfaces planes having d ≈ 0.14 nm. The structure obtained by pulsed high-voltage action makes it possible to increase the hardness of the coating to 32 GPa and reduce the friction coefficient to 0.32 in the "chromium nitride-steel" system and to 0.11 in the "chromium nitride-diamond" system. The results obtained are explained from the viewpoint of increasing the mobility of atoms and the formation of cascades of displacements when using an additional high-voltage potential in the pulse form during the deposition of chromium-based coatings.
Mixing on the Boundaries of Layers of Multilayer Nanoperiod Coatings of the TiNх/ZrNх System: Simulation and Experiment
(Sumy State University, 2017) Sobol, O. V.; Meylekhov, A. A.; Mygushchenko, R. P.; Postelnyk, A. A.; Sagaidashnikov, Yu. Ye.; Stolbovoy, V. A.
Using the complex of methods for attestation of the structural state in combination with computer simulation and measurement of mechanical properties (hardness), the influence of the period Λ on the mixing process on the interlayer boundaries of multilayer coatings TiNх/ZrNх is studied. The formation of two phases (TiN and ZrN) with one type of crystal lattice (structural type NaCl) is identified in the layers of multiperiodic compositions TiNx/ZrNx with a period of Λ = 20 ... 300 nm. At Λ = 10 nm, the formation of a solid solution (Zr, Ti)N, as well as a small volume of the TiN phase is revealed on XRD spectras. The presence of TiN component is due to the larger initial value of the layer based on titanium nitride. To explain the results obtained, the results of computer simulation of damage at the atomic level during bombardment by ions accelerated in the Ub field are used. The critical thickness of mixing (about 7 nm) in the TiNx/ZrNx system is determined upon condition that Ub = – 110 V. It is established that a decrease in the period from 300 to 20 nm leads to increase in hardness. The highest hardness of 44.8 GPa corresponds to the superhard state. It is established that the critical thickness of radiation-stimulated defect formation has a significant effect on the stress-strain state and hardness of coatings with a small Λ ≈ 10 nm. In this case, relaxation of the stress-strain compression state occurs and the hardness decreases. However, the formation of a solid solution, while retaining part of the unreacted layer of titanium nitride at Λ = 10 nm, makes it possible to obtain an ultrahigh (44.8 GPa) hardness of the coating.

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