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Vashchyshyn L.V.,Ukrainian Academy of Sciences | Nichoha V.O.,Lvivska Politekhnika National University
Materials Science | Year: 2014

We construct an artificial neural network, with the help of which and the coefficients of continuous wavelet transformation, we can automatically detect signals from transverse cracks in rails in the defectograms recorded by a flaw-detector car. In the case where the mother wavelet function of the continuous wavelet transform and a configuration of the artificial neural network are successfully chosen, we can detect signals from defects in the initial stages of their initiation, i.e., within the period of time when the signals are comparable with noise. © 2014, Springer Science+Business Media New York.


Mel'nyk I.V.,Lvivska Politekhnika National University
Materials Science | Year: 2015

To establish the mean stiffnesses of reinforced-concrete beams with effective tubular inserts in bending, we used the finite-element method and the theory of shells. According to the results of theoretical analysis, it is shown that the cylindrical stiffnesses of reinforced-concrete floors with tubular inserts are different in mutually perpendicular directions. Based on the results of numerical simulations, we obtain the comparable values of cylindrical stiffnesses for monolithic reinforced-concrete floors of identical mass with tubular inserts of square, rectangular, and circular shapes. © 2015 Springer Science+Business Media New York


Musii R.S.,Lvivska Politekhnika National University
Materials Science | Year: 2013

We formulate a dynamic centrally symmetric problem of thermomechanics for a hollow conducting sphere subjected to a homogeneous nonstationary electromagnetic action in the decaying sinusoid mode. We obtain the solution of this problem by using the cubic approximations of the azimuthal component of the vector of magnetic field and the radial component of the stress tensor in the radial coordinate. We also perform the numerical analysis of the thermal stressed state and the load-carrying capacity of nonferromagnetic spheres under the indicated conditions. © 2013 Springer Science+Business Media New York.


Banakhevych Y.V.,Ukrtransgaz | Dragilev A.V.,Engineering Technologies Private Enterprise | Kychma A.O.,Lvivska Politekhnika National University
Materials Science | Year: 2014

Within the framework of the shell theory, we develop a mathematical model that describes the axisymmetric stress-strain states of multilayer annular welded joints of the pipes under the action of residual incompatible strains localized near the weld. The residual stresses are evaluated on the basis of the solutions of inverse problems of the shell theory with intrinsic stresses by using the experimental data obtained by the method of speckle interferometry. We created an experimental installation and special software that enable one to evaluate and reproduce residual stresses in the zone of multilayer welded joint. The plots of circumferential residual stresses as functions of the distance from the axis of the weld are presented. © 2014, Springer Science+Business Media New York.


We formulate dynamic plane axisymmetric problems of thermomechanics for long conducting hollow and solid cylinders subjected to a homogeneous nonstationary electromagnetic action. By using the cubic approximation of the axial component of the vector of magnetic-field strength and the radial component of the vector of displacements with respect to the radial coordinate, we obtain the solutions of these problems and perform the numerical investigation of the thermal stressed state and load-bearing ability of the analyzed nonferromagnetic cylinders under the electromagnetic action in the mode with pulsed modulating signal. © 2015 Springer Science+Business Media New York

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