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|Mykhas’kiv V. V. and Kalyniak O. I. Nonstationary disturbances of a 3-D elastic matrix with a rigid disk inclusion
SUMMARY. By the time-domain boundary integral equation method the problem on the propagation of nonstationary elastic waves in a 3-D infinite matrix with a thin-walled rigid movable inclusion is solved. Perfect mechanical contact between the inhomogeneity and the matrix is assumed. The marching algorithm for the discretization of the obtained equations, which takes into account the solution singularity at the contour of inclusion, is proposed. Under normal incidence of nonstationary elastic waves with different profiles on a circular disk-shaped inclusion the temporal dependences of its displacements and mode I stress intensity factors are determined.
|Kit H. S. and Sushko O. P. Thermoelastic state of a semi-space with a perpendicular
to its edge heat-active circular crack
SUMMARY. Using the boundary integral equation method, the problem of stationary heat conduction and thermoelasticity for a semi-infinite body with a disk crack perpendicular to its boundary is solved. The temperature or heat flow is given on the crack surface. The boundary is a circular load-free and thermally insulated or is sustained at zero temperature. The influence of occurence depth of the crack on the value of stress intensity factor (SIF) is studied for the given constant temperature or heat flow on it. Unlike the constant force loading under thermal loading of a crack, the SIF reach their maximum not from the side of the half-space boundary but from the opposite side
|Holyboroda I. M. Description of deformation of materials with the shape memory
under thermomechanical alternating loading
SUMMARY. The phenomenological model of the irreversible dislocational deformation for Fe-based shape memory materials is presented. Abnormal drop of the yield stress in the interval above the start temperature of the direct martensitic transformation is described. Stress- and temperature-induced residual microstresses are taken into consideration. The applicability of the model is demonstrated by comparison of the calculations with experimental data for 66Fe9Cr5Ni14Mn6Si steel.
|Khapko B. S. Shallow prismatic shell in nonuniform temperature field
SUMMARY. The thermoelasticity of prismatic shallow shell composed from two plate elements was investigated. By using the finite integral transforms method analytical solutions of the problem of heat conductivity and thermoelasticity were obtained in the form of double series. Numerical analysis of forces and moments distributions along coordinate axes was performed for two different values of shell break angles.
|Martyniak R. M., Malanchuk N. I., and Monastyrskyi B. Ye. . Shear of mutually pressed semi-planes with a surface groove. Part I. A complete contact
SUMMARY. The plane problem of the shear of mutually pressed half-planes, one of which has a surface shallow groove, is considered. Using the Kolossov – Myskhelishvili complex potentials the problem is reduced to a singular integral equation, which for particular form of the groove is solved analytically. Three ranges of external tangential loading for which behaviuor of the contact couple qualitatively differs: the full adhesion of the bodies, slip of the surface points at the local zones, slip of the bodies relative to each other has been established. The behaviour of the system under local slip is analyzed in detail.
|Shatskyi I. P. Closure of a longitudinal crack in a shallow cylindrical plate
SUMMARY. The contact interaction of axial crack edges under bending of a shallow cylindrical shell has been considered in twodimensional statement using the model of contact along a line. The influence of the surface curvature and crack closure on the stress state and limit equilibrium of a shell has been investigated. The comparison of numerical data with asymptotic solution of the problem is given.
|Kovalchyk Yu. I. and Shyrokov V. V. Modelling of temperature flash in periodic friction contact of surfaces
SUMMARY. The summarized mathematical model for the calculation of the temperature flash at the sliding interaction of microlug and discreet and periodical friction surface is proposed. The periodical discreetness of the friction surface and its connection with physical structure of metal have been taken into account.
|Drobenko B. D. Rational conditions of high-frequency heat treatment of a steel cylinder
SUMMARY. The various regimes of high-temperature induction heating of a ferromagnetic cylinder are considered. It is shown, that by choosing the frequency of the current and conditions of cooling it is possible to achieve the residual stresses in the cylinder, what allows to determine the rational regimes of its treatment.
|Fedirko V. M., Pichuhin A. T., Lukianenko O. H., and Onuferko V. S. Solid solution hardening of titanium alloys surface by vacuum heat treatment
SUMMARY. Kinetic parameters of interaction of ВТ1-0, ВТ5, ОТ4-1 and ВТ16 titanium alloys with a rarefied gas environment were established. The relationship between parameters of chemicothermal treatment (temperature, T, time, τ, and pressure, p), and the level of interstitial hardening of the metal surface layers and its phase-structural state was found. It is established that at the identical saturation parameters (T, τ, p) of titanium alloys the layers of different layer microhardness and layer thickness are formed. Oxygen diffusion hardening is the most sensitive to the monophase -titanium ВТ1-0, ВТ5 alloys and ОТ4-1 pseudo--alloyin which the hardness and its gradient in the hardening layer increase considerably. With the increase of β-phase (ВТ16) content, the change of parameters of chemicothermal treatment has less influence on surface layer hardness, however the depth of the fixed zone grows with the increase of T and τ.
|Yaskiv O. I., Pohreliuk I. M., and Diuh I. V. Dependence of interaction between titanium and carbon-nitrogen containing environment on saturation parameters
SUMMARY. It was shown that the specific saturation surface area can intensify the nitride formation nitriding in graphite powder. The nitride coating thickness increases with the specific saturation surface decrease. However it does not effect the coatings phase composition, but only assists in redistribution of the nitride reflexes intensities, indirectly influencing their properties.
|Zakharchuk V. H., Tsyrulnyk O. T., and Nykyforchyn H. M. Electrochemical properties of steels of a simulated hydrogen galvanic couple
SUMMARY. The effect of preliminary hydrogenating of carbon steels and low-alloyed steels on their electrochemical behaviour in hydrogen galvanic couple (HGC) “hydrogenated-nonhydrogenated steel” has been investigated. At the same conditions of hydrogenation the HGC current is not determinated by HGC electromotive force but by the level of the electrode polarization, which is dependent on ratio of electrode areas. Polarization dependences indicate that electrochemical processes in HGC are governed by the electrochemical kinetics laws and are of activation nature. HGC current is proportional to hydrogen concentration absorbed by steel and correspondingly the effectivness of HGC work can be put in a base of the NDT method of hydrogen content in steel. Electrochemical properties of steels are similar to the properties of the juvenile surface with increase of the hydrogen contents in them: the electrod potential becomes innoble, the polarization decreases and sharply increases the anode reaction rate.
|Poriadchenko N. Yu., Kuzmenko M. M., Oryshych I. V., Khmeliuk N. D., Kulak L. D., and Kalashnikova L. O. Heat-resistance in air of titanium alloys, alloyed
with silicon, aluminium and circonium
SUMMARY. Oxidation of ВТ1-0 titanium alloy alloyed with silicon, aluminium and zirconium in air at 800C for 30 h was investigated. It was shown that alloying of BT1-0 alloy with silicon up to 6 mass.% increases the heat resistance more than 2 times. This effect is caused by its influence on diffusion in metal and in scale and by the change of the scale morphology.
|Zhuravchak L. M. Quasi-stationary model of electromagnetic field for a piece-wise homogeneous body
SUMMARY. The bi- or three-dimensional body of an arbitrary shape, containing inclusions, in the perfect electromagnetic contact with the matrix is considered. On the boundary surface of the body the conditions of the third type are set. A method of common usage of the fundamental solution of non-stationary equation of heat conductivity, near-boundary and contact element techniques and the stepwise time scheme of a unique initial condition, for construction of the integral representations of the electromagnetic field strength vector components in an arbitrary space-time point is proposed. Use at the media interface in case of perfect electromagnetic contact between zones of the contact elements instead of boundary or near-boundary elements has allowed to satisfy automatically the first condition of contact (equality of components of electric field strength vector). That reduces the number of unknown fictitious current sources in comparison with traditional indirect methods of boundary or near-boundary elements.
|SCIENCE FOR PRODUCTION |
Lychkovskyi E. I. Durability calculation of a hip joint, made of 08X18H10T steel by fracture mechanics methods
SUMMARY. Corrosion fatigue crack growth resistance of 08X18H10T steel in biological solution “PICЛT’ was investigated. These tests simulated the human muscular tissues. A methods of calculation and determination of optimal dimentions of endoprothetic appliance for hip joint in the maximum stressed dangerous cross-section is proposed. It has been shown that 08X18H10T steel can be used as a material for orthopaedic implantants.
|Malina J., Samardzic I., and Gliha V. Susceptibility to hydrogen induced cracking of weld beads on high-strength structural steel|
|Paustovskyi O. V., Kyrylenko S. N., Alfintseva R. A., Kostenko O. D., Kurinna T. V.,
and Tereshchenko V. S. Electric-spark alloying of steels with ВК alloy-based materials with carbide-chromium additives
SUMMARY. The investigations showed that during electric spark treatment of 45 steel by the electrodes made of WC + Co + (2...4)% Cr3C2 hard alloys obtained by the sintering method leads to the formation of intermediate zone at the border “coating – substrate”. The zone is a result of cavitation mixing of the electrode materials in spark discharge. The composition of the formed zone corresponds to the that of high-alloyed high-speed steel. The presence of the above-mentioned zone increases bond strength of the coating with the substrate, the depth and also wear-resistance of the obtained layer.
|Piddubnyi V. K., Zin’ I. M., Lavryshyn B. M., Bilyi L. M., Kolodii Ya, Yo.,
and Ratushna M. B.
The influence of carbon-containing current conductive
fillers on epoxy coating properties
SUMMARY. It is established that antistatic coatings based on commercial primer EP-0010 with addition of graphite have low adhesion to metal and tensile strength, but are resistant to the working environment. The use of channel black as a current conductive additive increases the strength of free films, optained on the bases of the given epoxy composition, in 1.5–3 times to compare with graphite filler, and decreases their mass losses in the working environment. The adhesion of EP-00100 epoxy coating modified with channel black is in 2–2.5 times higher than that for coatings with graphite filler. The use of plasticizer based on epoxidised vegetable oil, instead of phthalat oil, is more prospective, this allows at the optimum content of components, to increase significantly the physicomechanical characteristics of untistatic epoxy coatings and their resistance to the working environment.
|SHORT REPORTS |
Prokhorenko S. V. Structure and viscosity of gallium, indium and tin melts close to recrystallization temperature
|Kulagin D. O. and Krist G.-Yu. Application of dimension theory for evaluation of the effect of aggressive environment on long-term strength|
|Rusynko A. K.Analytical description of the effect of annealing time after deformation on the steady-state creep of metals|
|IN SCIENTIFIC CIRCLES |
Balytskyi O. I. New achievements of fracture mechanics of materials and structures
|Nykyforchyn H. and Zagorski A. Development of the Ukrainian-Polish cooperation in researches on metals hydrogen degradation|