Wyniki wyszukiwania - BazTech

1

The modelling of temperature-dependent stress-strain curves for weldable steels

Winczek J., Mičian M., Ivanov V.

Journal of Applied Mathematics and Computational Mechanics

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2018

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Vol. 17, nr 3

111--117

EN

The calculation of stresses in the steel elements subjected to the thermomechanical loads requires taking into account the influence of temperature on mechanical properties of a material, including the stress-strain curve. The simplified and extended computational models of temperature-dependent tensile curves have been discussed. The methodology of the stress-strain curve construction in the entire temperature range of the solid state of the material has been proposed. The considerations are illustrated by the examples of calculated stress-strain curves in different temperatures for S235 and S355 welding steels.

2

Experimental diagnostic research of fixture

Ivanov V., Dehtiarov I., Denysenko Y., Malovana N., Martynova N.

Diagnostyka

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2018

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Vol. 19, No. 3

3--9

EN

In the article the experimental research of the flexible fixture is shown, which provides sufficient accessibility and allows to perform multiaxis machining of parts, e.g. of levers with one setup. The experimental studies compared with the results of numerical simulation that were previously obtained, confirmed that the proposed fixture design meets all accuracy parameters. The results of experimental studies on the determination of displacements have shown that the values of displacements, determined statically, in the proposed fixtures are smaller than the dedicated ones. The analysis of the data of determination of the frequencies of the proper oscillations in the machining of the levers from steel and cast iron has confirmed that the first critical frequency of the fixture significantly exceeds the similar parameter of dedicated fixture.

3

Research into the technological process of extrusion - type forging of automotive wheel made of magnesium alloy produced with the help of loaded - die

Petrov P., Voronkov V., Plotnikov A., Ivanov V., Petrov M., Basyuk S.

Computer Methods in Materials Science

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2011

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Vol. 11, No. 2

251-258

EN

The presented paper deals with the manufacturing of the automotive wheels. It focuses on the effect of the forging die geometry on the loading conditions during the hot forging of the preform of the wheel. The investigation within the scope the paper has been done on the basis of the finite-element (FE) modelling. It was carried out by means of the FE commercial codes QFORM-2D/3D. The FE modelling of the hot forging of the preform of the wheel showed the potentiality of the chosen scheme of the combined extrusion-type forging with the help of a loaded-die. The relationships between the geometrical parameters of the die and the technological parameters of the forging were established on the basis of numerical simulation.

PL

Artykuł dotyczy wytwarzania felg samochodowych. Badany jest wpływ kształtu matrycy na siły w procesie kucia na gorąco. Do badań wykorzystano komercyjny program MES QFORM-2D/3D. Symulacje kucia felgi samochodowej pokazały potencjalne możliwości kombinowanego procesu wyciskania-kucia we wstępnie obciążonych matrycach. Wyznaczone zostały zależności pomiędzy kształtem matrycy i parametrami technologicznymi kucia.

4

Investigation of Al Nanopowders Produced by the Exploding Wire Method

Sedoi V., Osmonaliev M., Chemezova L., Volkova G., Ivanov V., Alekseev A.

Central European Journal of Energetic Materials

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2007

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Vol. 4, nr 1-2

17-30

EN

The impetus for this research came from fundamental and applied questions connected with specified characteristics of Al nanopowders, theirs controlled syntheses and passivation, and their activity as high energetic ingredients in solid propulsion and in aluminum-water gels. Different conditions of powder syntheses by the exploding wire method and powder passivation were used: syntheses at low-pressure gases (Ar, N2, CO2) and passivation in atmospheric-pressure gases (air, N2, CO2). Investigations of particle sizes and morphology have been accomplished with a 125-kV transmission electron microscope. The specific surface area S has been determined by BET method. Particles are predominately spherical, BET surface area was of 15-40 m2/g. The composition and surface properties of nanopowders produced under various conditions were studied by mass-spectroscopy techniques at temperatures of 0-450 C, by electron and X-ray diffraction methods, and by elemental analysis methods. To determine activities of the powder samples in the combustion reactions, the Differential Thermal Analysis, Thermogravimetry, and reaction with water were conducted. Active metal contents have been determined from amount of impurities and hydrogen extracted in direct thermohydrolysis of nanopowders by distilled water at 60 C. Kinetics of gas evolution was determined therewith and shows two steps. Active aluminum content is within range of 16-80%. A composition of adsorbed gases and dynamics of desorption in vacuum have been investigated too. Correlation between conditions of nanopowder syntheses and specific surface and chemical activity in reaction with water and maximum oxidation degree have been determined. Keywords: nanopowders, characterization, passivation, oxidation, combustion

5

Electrical resistivity of RNi4Al and RNi4Cu

Toliński T., Ivanov V., Kowalczyk A.

Materials Science Poland

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2006

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Vol. 24, No. 3

789--793

EN

A comparative studies of the temperature dependence of resistivity for RNi4X (X = Al, Cu; R = Y or rare earth) compounds are presented. These results are also compared to the previously studied RNi4B. The ordering temperatures are well identified on the ?(T) curves. The residual resistivity ?0 of RNi4Al is several times higher than for RNi4Cu and RNi4B. The YNi4X compounds are included in these studies as the nonmagnetic isostructural reference materials. The phonon contribution has been determined for both Y-based compounds employing the Bloch-Grüneisen formula. The CeNi4X compounds show a shallow minimum in ?(T) at low temperatures (about 15 K). This anomaly has been ascribed to a Kondo impurity - like behavior. For the other rare earths, the ?(T) dependences below TC have been analyzed assuming the scattering on magnons as the predominant mechanism.