Browsing by Author "Stankevych, Volodymyr Z."
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Item Cracks Interaction in the Elastic Composite under Action of the Harmonic Loading Field(Tbilisi State University, Georgia, 2018) Stankevych, Volodymyr Z.; Butrak, I. O.; Kovalchuk, Vitalii V.EN: A three-layer composite with penny-shaped cracks in the field of harmonic torsional loading is considered. The solutions are chosen in the form of Helmholtz potentials with densities that characterize unknown crack opening functions. The problem is reduced to the solution of the system of two-dimensional boundary integral equations (BIFs). The influence of the frequency of the applied load, the ratio of the elastic constant parameters of the composite on the dynamic stress intensity factors in the defect vicinity is investigated.Item Estimation of Carrying Capacity of Metallic Corrugated Structures of the Type Multiplate MP 150 During Interaction with Backfill Soil(PC "Technology Center", Ukrainian State University of Railway Transport, Kharkov, 2018) Kovalchuk, Vitalii V.; Kovalchuk, Yuri; Sysyn, Mykola P.; Stankevych, Volodymyr Z.; Petrenko, Oleksiy V.EN: We estimated the stressed state of a railroad structure with a large cross section spanning more than 6 m, which is made from metallic corrugated sheets of the type Multiplate MP 150. The stressed-strained state of the corrugated structure was estimated depending on the residual deformation of vertical diameter of the pipe, the modulus of elasticity of backfill soil, and the degree of compaction. The study conducted has demonstrated that maximum stresses occur on the horizontal sides of a metallic pipe, and maximum deformations ‒ in the pipe vault. It was established that an increase in the degree of compaction of backfill soil leads to a decrease in the stresses in a metallic pipe by almost half. The stresses grow much faster with an increase in irregularity on the railroad track. Numerical calculations have shown that the equivalent stresses exceed the permissible magnitude of 235 MPa when the degree of compaction of backfill soil is below 90 % and an operational irregularity on the track develops beyond the permissible magnitude. Operational observations have shown that the pipe is most vulnerable, in terms of resistance against the formation of a plastic hinge, in the initial period of operation when the backfill soil has not yet reached the standard compaction. At the initial stage of operation of a metallic corrugated pipe it is necessary to improve the level of technological control in order to timely detect railroad track's irregularities that exceed the standards, and to eliminate them. Under normal operational conditions, a metallic corrugated structure has a rather large reserve of carrying capacity, which amounts to 80 %. However, these structures, despite their high initial strength margin, are very sensitive to an increase in external dynamic loads due to the occurrence of irregularity on the railroad track.Item Rayleigh Wave Diffraction on Surface Elastic Inclusion in the Half-Space(IEEE, 2020) Stankevych, Volodymyr Z.; Zhbadynskyi, I. Y.; Vdovychyn, I. Y.EN: The diffraction of the Rayleigh wave on a half-circular elastic inclusion which is located perpendicular to the half-space surface is considered. The low-frequency oscillations spectrum is analyzed. Using the method of boundary integral equations (BIE), the problem is reduced to the integral equations with respect to unknown defect opening functions. The mode-I stress intensity factors as functions of angular coordinate of an inclusion front point and wave number for various relations between the materials parameters are computed.