ivska Politekhnika National University

L'viv, Ukraine

ivska Politekhnika National University

L'viv, Ukraine

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Hvozdyuk M.M.,Ukrainian Academy of Sciences | Babyak I.P.,ShulGin State Road Research Institute | Hembara T.V.,ivska Politekhnika National University | Kostiv R.B.,Ukrainian Academy of Sciences
Materials Science | Year: 2014

We determine the characteristics of static and fatigue strength of basalt reinforcement with nominal diameters of 4, 6, 8,10, and 12 mm in the cases of static and cyclic tension of the specimens. In particular, we establish the fatigue limit σ N for a basic number of cycles N equal to 2·106 cycles. © 2014 Springer Science+Business Media New York.


Hachkevych O.R.,NASU Pidstryhach Institute for Applied Problems in Mechanics and Mathematics | Musii R.S.,ivska Politekhnika National University
Materials Science | Year: 2011

A procedure is proposed for the prediction of the bearing ability of conducting structural elements under the action of electromagnetic pulses. For bodies of canonical shapes, i.e., plates and hollow and solid cylinders or spheres, the initial-boundary-value problems are formulated for the evaluation of the parameters of electromagnetic fields, temperature, and the components of the tensor of dynamic stresses. We construct the dependences of the maximum values of stress intensities in these nonferromagnetic bodies on the time parameters of electromagnetic pulses and the maximum magnetic-field intensity on the surfaces of the bodies. These dependences are then used to determine the critical values of the analyzed quantities corresponding to the loss of the bearing ability of the body. © 2011 Springer Science+Business Media, Inc.


Prokopovych I.B.,NASU Pidstryhach Institute for Applied Problems in Mechanics and Mathematics | Osadchuk V.A.,ivska Politekhnika National University
Materials Science | Year: 2011

For an isotropic material, we construct the exact local equation for the influence of the stress tensor on the tensor of magnetic permeability. It is shown that, in the general case, this influence is determined by the magnetostriction properties of the material and, to a lesser degree, by the dependence of its elasticity on the applied magnetic field. The principal axes of the stress tensor are also the principal axes of the tensor of permeability. However, the spherical part of the tensor of permeability also depends on the orientation of the principal axes of stresses relative to the magnetic field. Under the assumption of weak magnetic dependence of the elastic properties, we deduce simplified expressions for the triaxial and plane stressed states. © 2011 Springer Science+Business Media, Inc.


Duryahina Z.A.,ivska Politekhnika National University | Borysyuk A.K.,ivska Politekhnika National University | Bespalov S.A.,NASU G.V. Kurdyumov Institute For Metal Physics | Pidkova V.Y.,ivska Politekhnika National University
Materials Science | Year: 2012

We investigate phase transformations in ion-nitrided surface layers of 12Kh18N10T steel subjected to thermal cyclic treatment (heating up to 1050 K follows by cooling at a rate of 30 K/min) by the method of magnetic analysis with the help of a vibrating-coil magnetometer, which enables us to affect the quasistable quantitative martensite-to-austenite ratio in the nitrided surface layer of steel. It is shown that, as a result of the thermal cyclic treatment, the temperature of the direct martensitic transformation in the nitrided surface layer increases from 380 K in the first cooling cycle up to 540 K in the fifth cooling cycle. © 2012 Springer Science+Business Media New York.


Tor-Swiatek A.,Lublin University of Technology | Suberlyak O.,ivska Politekhnika National University | Krasins'Kyi B.,ivska Politekhnika National University | Dulebova L.,Technical University of Košice
Materials Science | Year: 2014

We study some strength characteristics and the structure of porous polypropylene extrudates obtained by the twin-screw extrusion. We use a ZSK-18 MEGAlab laboratory twin-screw extruder (Coperion Werner & Pfleiderer GmbH) with the ratio of length to the diameter of the screws L/D = 24 and the Expancel 950MB80 and 950MB120 innovative foaming agents. The dependences of the strength characteristics of the porous extrudate on the extrusion rate and the contents of foaming agents are analyzed. © 2014 Springer Science+Business Media New York.


Zelenyak V.M.,ivska Politekhnika National University
Materials Science | Year: 2012

We study a two-dimensional problem of thermoelasticity for a plane containing a two-component circular inclusion and a crack. The problem is reduced to a system of two singular integral equations on closed (boundary of the inclusion) and nonclosed (crack) contours. The numerical solution of these integral equations is obtained by the method of mechanical quadratures. We also study the effect of thermal and mechanical properties of the components of the inclusion on the stress intensity factors at the crack tips. © 2012 Springer Science+Business Media New York.


Havrysh V.I.,ivska Politekhnika National University | Kosach A.I.,ivska Politekhnika National University
Materials Science | Year: 2012

By using distributions, we deduce the heat-conduction equation with discontinuous and singular coefficients for an isotropic piecewise homogeneous layer containing a foreign cylindrical inclusion with heat release. With help of a piecewise linear approximation of temperature on the boundary surfaces of the inclusion and the Hankel integral transformation, we construct the numerical-analytic solution of the boundary-value problem of heat conduction with heat transfer. We also perform the numerical analysis for the case of a three-element layer containing an inclusion in the middle element. © 2012 Springer Science+Business Media, Inc.


Musii R.S.,ivska Politekhnika National University
Materials Science | Year: 2011

A dynamic centrally symmetric problem of thermomechanics is posed for a hollow conducting sphere subjected to a uniform nonstationary electromagnetic action. By using the cubic approximations of the azimuthal component of the magnetic-field strength and the radial component of the stress tensor in the radial coordinate, we obtain the solution of the problem and perform the numerical analysis of the thermal stressed state and the load-carrying capacity of nonferromagnetic spheres under the electromagnetic action in the mode with pulsed modulating signal. © 2011 Springer Science+Business Media, Inc.


Havrysh V.I.,ivska Politekhnika National University | Fedasyuk D.V.,ivska Politekhnika National University | Kosach A.I.,ivska Politekhnika National University
Materials Science | Year: 2011

Using generalized functions, we obtain a heat-conduction equation with discontinuous and singular coefficients for an isotropic layer with heat-generating foreign cylindrical inclusion. Using a piecewise-linear approximation of temperature on the surfaces of the inclusion and the Hankel integral transformation, we construct an analytic solution of the boundary-value problem of heat conduction with heat emission. A numerical analysis of the considered system is carried out. © 2011 Springer Science+Business Media, Inc.


Yavors'Kyi V.T.,ivska Politekhnika National University | Perekupko T.V.,ivska Politekhnika National University | Mudryi O.I.,ivska Politekhnika National University
Materials Science | Year: 2013

We study the influence of the concentrations of AgNO3 (0.06-0.32 mole/liter) and NH4NO3 (0.1-0.5 mole/liter) in the initial solution and the hydrodynamic conditions for Rev varying within the range 12,950-46,700 on the physicochemical properties of silver powders obtained from secondary solutions of silver (I) nitrate by contact precipitation with magnesium chips within the range 293-323 K. At a temperature of 313 K, for the stoichiometric amount of magnesium chips, turbulization of the medium corresponding to Re v = 24,200, and the contents of AgNO3 and NH4NO3 in the initial solution equal to 0.06-0.1 mole/liter and 0.25 mole/liter, respectively, we obtain silver powders with a bulk density of 1.09 g/cm3, a specific surface area of 2520 cm 2/g (determined according to the gas permeability), and mean particle sizes of 1.0-3.0 μm. Powder particles have perfect geometric shapes with tetragonal and hexagonal symmetry about the axis of growth. The content of Ag in the powder is equal to 99.9 wt.%. It is shown that, by choosing and combining the conditions of contact precipitation, we can get powders with prescribed physicochemical properties. © 2013 Springer Science+Business Media New York.

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