Donbass National Academy of Civil Engineering and Architecture

Makiyivka, Ukraine

Donbass National Academy of Civil Engineering and Architecture

Makiyivka, Ukraine
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Perig A.V.,Donbass State Engineering Academy | Golodenko N.N.,Donbass National Academy of Civil Engineering and Architecture
Advances in Materials Science and Engineering | Year: 2017

Thepresent article is focused on a phenomenological description of a polymerworkpiece EqualChannel Angular Extrusion (ECAE) through 2θ-dies of Segal and Iwahashi geometries with a channel intersection angle 2θ = 105° with fixed and movable external inlet and outlet die walls. The local flow dynamics, including the formation of macroscopic rotation and a dead zone appearance during the flow of plasticine, paraffin, and wax workpiece models through the subject die configuration was studied using physical simulation techniques. The present article utilizes a Computational Fluid Dynamics (CFD) numerical approach to a theoretical description of 2D viscous flow of incompressible Newtonian continuum through the stated die geometries. The boundary value problem for the Navier-Stokes equations in the curl transfer form for the local viscous flow was formulated and numerically solved with a finite-difference method.Theoretical CFD-derived plots with computational flow lines, dimensionless flow and curl functions, flow velocities, and tangential stresses for viscous material flow through the stated die geometries have been generated and described. As a first rheological approximation the derived computational results provide the theoretical description of physical simulation experiments and visualize the formation of ECAE-induced rotational modes of large deformations like macroscopic rotation and rotational inhomogeneity. Copyright © 2017 Alexander V. Perig and Nikolai N. Golodenko.


Aleksandrov V.D.,Donbass National Academy of Civil Engineering and Architecture | Pokyntelytsia O.A.,Donbass National Academy of Civil Engineering and Architecture | Sobolev A.Y.,Donbass National Academy of Civil Engineering and Architecture
Technical Physics | Year: 2017

Different thermal hysteresis processes associated with macroobjects have been analyzed using heating and cooling thermograms with regard to liquid–solid phase transformations. Two types of thermal hysteresis for equilibrium and nonequilibrium crystallizations have been revealed. The paths of Gibbs energy variation are shown for both cases. © 2017, Pleiades Publishing, Ltd.


Samsonenko S.N.,Donbass National Academy of Civil Engineering and Architecture | Samsonenko N.D.,Donbass National Academy of Civil Engineering and Architecture | Timchenko V.I.,Donbass National Academy of Civil Engineering and Architecture
Semiconductors | Year: 2010

The temperature dependence of the electrical conductivity of natural semiconducting diamonds of Ic type has been studied. The activation energies of the dislocation acceptor centers (induced by plastic deformation) are found to be e{open}3 = 0.29-0.36 eV. Four natural diamonds of IIa type with a resistivity of 1015-1016 Ω cm were plastically deformed to prove the formation of levels with the activation energy e{open}3 in semiconducting diamonds. The deformation led to a decrease in resistivity by one to two orders of magnitude and to the formation of a new level with e{open}3 = 0.29 eV, which is characteristic of semiconducting diamonds. We expect deformation to induce dislocation centers, not only in Ic-type diamonds, but also in natural semiconducting diamonds of IIb type. © 2010 Pleiades Publishing, Ltd.


Perig A.V.,Donbass State Engineering Academy | Golodenko N.N.,Donbass National Academy of Civil Engineering and Architecture
Chemical Engineering Communications | Year: 2014

The present work is focused on a 2D fluid dynamics description of equal channel multiple angular extrusion (ECMAE) or equal channel multiple angular pressing (ECMAP), using a numerical mathematical simulation for viscous flows of physical polymeric materials models through a die with a movable inlet wall. A numerical finite-difference model for plane viscous Newtonian flow of an incompressible continuous medium in a multiple-angle region with a movable inlet die wall, based on the formulation and numerical solution of the boundary value problem for the Navier-Stokes equations in curl transfer form, is derived. A numerical estimation of the influence of the direction of movement of a movable entrance die wall on computational flow lines, stream and curl functions, and viscous flow velocity fields was carried out within the scope of the developed model for a movable inlet wall of the die. The proposed hydrodynamic approach extends the ideas concerning the dynamics of the macroscopic rotation formation within the volume of the viscous physical model of a polymeric material during ECMAE or ECMAP through a die with a movable inlet wall. © 2014 Copyright Taylor & Francis Group, LLC.


Kalashnikova O.A.,Donetsk National Technical University | Dremov V.V.,Donbass National Academy of Civil Engineering and Architecture
Journal of Engineering Physics and Thermophysics | Year: 2016

A nonstationary problem of solidification of an ingot in molds with walls of varying thermal conductivity has been solved by the variational method with account taken of forced convection in the liquid phase of the metal. A formula for the temperature distribution in the liquid phase and the dependence of the time of advance of the solidification front on its coordinates have been obtained. Numerical calculations of the time of solidification of the ingot in castiron and ceramic molds have been done at different convection rates. © 2016 Springer Science+Business Media New York


Aleksandrov V.D.,Donbass National Academy of Civil Engineering and Architecture | Frolova S.A.,Donbass National Academy of Civil Engineering and Architecture | Amerkhanova S.K.,Karaganda State University
Russian Metallurgy (Metally) | Year: 2016

Cyclic thermal analysis is used to study the effect of overheating of the eutectic Ga–8.5 mol % Sn melt on the presolidification supercooling. It is found that, when the liquid eutectic is overheated above the eutectic temperature (Te = 293.5 K) and is subsequently cooled, the dependence of the presolidification supercooling on the overheating temperature exhibits monotonic ascending behavior. The maximum supercooling after heating of the melt to 339 K is 26 K. The kinetic and thermodynamic parameters of eutectic solidification are calculated using the thermal analysis curves measured during melting. © 2016, Pleiades Publishing, Ltd.


Perig A.V.,Donbass State Engineering Academy | Golodenko N.N.,Donbass National Academy of Civil Engineering and Architecture
Materials Research | Year: 2016

The present article is focused on a 2D computational fluid mechanics study of local viscous flow dynamics and the formation character of rotary modes of deformation during Equal Channel Multiple Angular Extrusion (ECMAE) of a polymer workpiece fluid model through a U-shaped die with parallel slants in channel intersection zones. The present local flow problem was experimentally analyzed using physical simulation methods and theoretically studied with numerical fluid mechanics techniques. The computational approach has been grounded on the numerical finite difference solution of the boundary value problem for the Navier-Stokes equations in the curl transfer form for the local viscous flow of incompressible Newtonian fluid through a U-shaped rectangular die with parallel slants. The derived research results allow us to draw a conclusion that the implementation of a geometric design of parallel slants within a 2-turn U-shaped die results in localization of the maximum tangential stresses within the workpiece volume to the vicinity of these parallel slants during ECMAE.


Aleksandrov V.D.,Donbass National Academy of Civil Engineering and Architecture | Sobolev A.Yu.,Donbass National Academy of Civil Engineering and Architecture
Inorganic Materials | Year: 2014

Using thermal analysis, we have constructed the phase diagram of the crystalline hydrate system Na2CO3·10H 2O-Na2S2O3·5H2O, which has been shown to have eutectic phase relationships. The eutectic composition is 27 wt % Na2CO3·10H2O + 73 wt % Na2S2O3·5H2O, and the eutectic temperature is T e = -0.92°C. We have determined the enthalpy of fusion of the alloys in this system and evaluated the activities of their components both at the liquidus temperatures and in metastable regions. The composition dependences of the above thermodynamic characteristics are shown to correlate with each other and to have extreme values at the eutectic composition. The results obtained lead us to recommend the eutectic mixture of the crystalline hydrates in this system as a heat storage material. © 2014 Pleiades Publishing, Ltd.


Perig A.V.,Donbass State Engineering Academy | Golodenko N.N.,Donbass National Academy of Civil Engineering and Architecture
International Journal of Advanced Manufacturing Technology | Year: 2014

The objective of this article is the description of advantages of a slanted die geometry, used for equal channel angular extrusion (ECAE) of materials. The prime novelty statement of the present research is an experimental flow pattern, obtained with circular gridlines and a numerical solution of a viscous flow 2D problem for the slanted die, derived with Navier–Stokes equations in curl transfer form. The geometry of the slanted die was chosen for the case of a rectangular die with channel intersection angle 2θ = 90° and with parallel slants in the channel intersection zone, where the slant width is equal to the inlet and outlet channel widths. Computational material flow kinematics, macroscopic rotation patterns, material flow velocity fields, tangential stresses, and punching pressure fields during viscous materials ECAE have been derived with a numerical finite-difference solution of the curl transfer equation for 2D viscous flow of incompressible continuum during ECAE. Theoretical results have been verified with physical simulation experiments by the introduction of initial circular gridlines. Both theoretical and computational results confirm the suitability and technological advantages of dies with parallel slants over the known Segal and Iwahashi dies for ECAE, as slanted convergent dies enable the reduction of the dead zone size and provide the minimization of dangerous macroscopic rotation during ECAE processing of both metal and polymer materials. © 2014, Springer-Verlag London.


Perig A.V.,Donbass State Engineering Academy | Golodenko N.N.,Donbass National Academy of Civil Engineering and Architecture
Mechanical Sciences | Year: 2015

This article is focused on a 2-D fluid dynamics description of punch shape geometry improvement for Equal Channel Angular Extrusion (ECAE) or Equal Channel Angular Pressing (ECAP) of viscous incompressible continuum through acute-angled Segal 2θ-dies with 2θ < 90°. It has been shown both experimentally with physical simulation and theoretically with computational fluid dynamics that for the best efficiency under the stated conditions, the geometric condition required is for the taper angle 2θ0 of the inclined oblique punch to be equal to the 2θ angle between the inlet and outlet channels of the Segal 2θ-die. Experimentally and theoretically determined rational geometric condition for the ECAP punch shape is especially prominent and significant for ECAP through the acute angled Segal 2θ-dies. With the application of Navier-Stokes equations in curl transfer form it has been shown that for the stated conditions, the introduction of an oblique inclined 2θ0-punch results in dead zone area downsizing and macroscopic rotation reduction during ECAP of a viscous incompressible continuum. The derived results can be significant when applied to the improvement of ECAP processing of both metal and polymer materials through Segal 2θ-dies. © Author(s) 2015.

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