Ukrainian Journal of Mechanical Engineering and Materials Science

6

Authors: Zoya Duriagina, Tetiana Tepla

The use of nitrogen as an alloying element presents a great interest for the improvement of properties of alloyed steels and special alloys. Superficial layers were formed by ionic implantation and by melting the surface by nitrogen plasma. After this kind of treatment, there form a continuous defect-free layers with a good adhesion to the surface. Surface treatment of steels and vanadium alloys increases their corrosion resistance and microhardness of surface layers. A combined supply of alloying elements into the melting area allows us to control the type and the density of secondary phases which are formed as the result of the reaction diffusion. In this way, depending on external needs, it is possible to increase either corrosive-electrochemical properties of the surface (when alloyed layers consist mainly of nitride or oxinitride phases) or wear resistance (when carbide or carbonitride phases will constitute a greater specific volume in the formed layers).

8

Authors: Іgor Vrublevskyi

The piece goods conveying by the vibratory conveyor with elliptical oscillations is considered. Elliptical oscillations of the conveyor track are realized when conveyor has independent drives of oscillations in the direction of conveying (longitudinal oscillations) and oscillations in the direction perpendicular to conveying plane (normal oscillations) with phase difference between them. Elliptical oscillations allow increasing conveying velocity and inclination angle of conveyor track in comparison with the simplest linear oscillations. Conveying velocity of parts moving along the track of conveyor varies with the change of phase difference angle and reaches a maximum with a certain angle, depending on several different parameters. This angle is called the optimal phase difference angle, and it depends on the amplitudes and frequency of the component oscillations, the track inclination angle, the frictional properties, impact parameters of conveying parts. As the experimental investigations have shown, the piece goods conveying is quite accurately described by the theory of a massive point particle moving on an inclined plane under the action of vibration. A system of nonlinear differential equations describing the conveying in continuous contact modes and in modes with hopping was composed. This system has been solved by gradual integration method with numerical calculation with any desired accuracy. This allowed us to study the dependence of conveying velocity on different parameters in the form of graphs. And for greater generality the study was conducted in dimensionless parameters. There were studied in detail the influence of dimensionless parameters on dimensionless velocity – the coefficient of velocity that is the ratio of conveying velocity to amplitude of longitudinal oscillations with a constant frequency. To verify the obtained dependences, the experimental investigations of conveying velocity were carried out on vibratory conveyor with removable tracks. The conveyor was fastened on the turntable, the inclination of which was varied by a screw jack. The amplitude of the component oscillations was varied by changing voltage applied to the electromagnetic drives, the phase difference between component oscillations was varied by the phase shifter. Waveforms of oscillations were recorded by vibration measurement equipment. The coefficient of friction was measured directly during conveying. The velocity was measured by the stopwatch. The comparison of experimental results with theoretical data has shown the excellent agreement in continuous contact modes and the acceptable match in modes with hopping. Based on the obtained graphs, the approximate formulas for calculating velocity and optimal phase difference angle were derived. The influence of frictional properties of the conveying parts, namely, the coefficient of friction on optimal in terms of velocity phase difference angle between the longitudinal and normal components of the elliptical oscillations is investigated. It is shown that the optimal phase difference angle decreases with the increase in the coefficient of friction. The approximate formula of optimal phase difference angle dependence on the coefficient of friction and track inclination angle is derived.

8

Authors: Yurij Kakhovskyi, Mykola Kakhovskyi

This paper discusses a technology of mechanized wet underwater welding of high-alloy corrosion-resistance steel. The main aim of the investigation is development of self-shielded flux-cored wire for wet underwater welding for the first time in the world practice. A mathematical method of experiment design was used for determination of quantity and quality characteristics. Besides, quantitive and qualitative indices of welding-technological characteristics such as weld metal gas saturation, stability of arc burning in water medium, and optimum composition of gas-slag-forming components of flux-cored wire charge were determined. Problems of this branch and current ways of performance of welding – repair operations on objects of high-alloy corrosion-resistance steel were outlined. Application of experimental self-shielded flux-cored wire in mechanized wet underwater welding of high-alloy corrosion-resistance steel allows increasing efficiency and quality of underwater welding-repair operations and receiving economical effect due to reduction of production downtime of object under repair. Usage of present technology provides for the possibility of complete elimination or partial reduction of human participation in welding process under extreme conditions in radioactive environment (in the case of NPP) and in welding at greit depth. The results of researches can be used for welding-repair operations in nuclear power plants, for ship repair and ship-raising operations and on hydraulic structures. Proposed innovation technology allows complete replacement of wet underwater welding using coated electrodes as well as eliminating human participation in welding-repair operations of critical structures under especially dangerous conditions such as underwater welding.

8

Authors: Ihor Virt, Yuriy Pavlovskyy, Ivan Hadzaman

Zinc oxide has numerous commercial device applications. Polycrystalline ZnO varistors, for example, are widely used in high voltage and power-related applications in industries such as microelectronics. One of the ways to control the properties of ZnO is its annealing in various environments, including oxygen, which leads to increased hardness and fracture toughness of ceramics. Therefore, the study of micromechanical properties of materials for modern electronics is an important and vital issue, both in terms of technology for improving quality of the final product and from the point of view of prospect of its practical use. The structural properties of the ceramic samples of ZnO have been studied. The average grain size has been defined. The micromechanical properties have been studied. The temperature conditions of increasing microhardness of ZnO have been defined after annealing in an oxygen atmosphere.

12

Authors: Ruslan Gorbatiyk, Igor Palamarchuk, Roman Chubyk

A lot of operations on trimming clean and finishing – stripping up treatment, first of all, removing of burrs, rounding and processing of borders, until recently time was carried out by hand, and hardly exposed to automation and became a serious obstacle in subsequent growth of the labor productivity. Machines with free kinematics connection between a tool and the treating parts is provided by the printing-down of all of the surface of the machine parts, that allows us to effectively treat both internal and external surfaces of the machine parts. The analysis of literary sources, patents and charts of methods of the intensification of the processes of vibro abrasive treatment, allowed us to determine the basic directions of development of vibro machines constructions for intensification of the trimming - stripping of the machine parts in a freely granular environment in default of hard kinematic connection between the parts and the tool. The feature of vibro abrasive treatment is a free kinematic connection between a tool and the machine parts, i.e. there exists complication in providing with the stable beforehand set technologically optimum influence of abrasive grains on treated parts under variable parameters of the working chamber of vibroabrasive machine. The purpose of this work is the development of a structural electromechanical model of a vibromachine for adaptive vibroabrasive treatment of the machine parts. To solve this problem, the structural electromechanical model of vibromachine for adaptive vibroabrasive treatment of machine parts was developed. The offered machine is able to provide minimum energy consumption on the vibrodrive of vibroabrasive machine due to providing and maintenance of the permanent resonance mode of operations of working chamber.

20

Authors: Bohdan Diveyev

The study aims to predict elastic and damping properties of composite laminated plates from the measured mechanical characteristics. The elastic constants and damping properties of a laminated element are determined by using experimental data and the results of a multi level theoretical approach. Solution examples for particular problems are given. On the basis of static three-point bending tests, measured eigenfrequencies, and refined calculation schemes, the elastic properties of layered composite beams were identified. For determining Young’s and shear moduli, the method of genetic minimization of error function was used. It is shown that, by employing combined criteria, the transverse elastic moduli can be determined uniquely. It is shown that, by employing combined criteria, the transverse elastic moduli can be determined. The elastic modules were also determined from measured vibration eigen-frequencies of the beams. New combined criteria of identification – schemes averaged over the calculation results for a homogeneous beam and for a sandwich with a core identical to the homogeneous beam and rigid outer layers are considered. The error function is chosen as the sum of error functions for the homogeneous beam, and for the sandwich. In the present study, combined identification schemes making it possible to unequivocally determine the transverse modules and Poisson ratio are suggested.