Ukrainian Journal of Mechanical Engineering and Materials Science

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Author: search.filters.author.Korendiy VitaliyHas files: Yes

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    Classical approach to determining the natural frequency of continual subsystem of three-mass inter-resonant vibratory machine
    (Lviv Politechnic Publishing House, 2019) Lanets Oleksii; Kachur Oleksandr; Korendiy Vitaliy
    Problem statement. The three-mass vibratory system can be defined by five basic parameters: inertial parameters of the masses and stiffness parameters of two spring sets. Unlike the classical discrete system, the discrete-and-continual one consists of two rigid bodies connected by one spring set that form the discrete subsystem, and of the reactive mass considered as deformable (elastic) body characterized by certain stiffness and inertial parameters, which are related with one another. Purpose. The main objective of the paper consists in determining the first natural frequency of the continual subsystem of the three-mass discrete-and-continual vibratory machine. Methodology. While carrying out the investigations, it is used the classical theory of oscillations of straight elastic rods. Findings (results). The engineering technique of determining the first natural frequency of the continual subsystem of the three-mass vibratory machine is developed and approved by means of analytical calculations and numerical simulation. Originality (novelty). The optimal diagram of supporting the continual subsystem (elastic rod) is substantiated. The possibilities of exciting the vibrations of the three-mass discrete-and-continual mechanical system using the eccentric drive are considered. Practical value. The obtained research results and the developed calculation techniques can be used be engineers and designers dealing with various technological and manufacturing equipment that use vibratory drive. Scopes of further investiga tions. While carrying out further investigations, it is necessary to develop the model of combined discreteand-continual system of three-mass vibratory machine, and to carry out the numerical simulation of the system’s motion under different operational conditions.
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    Analysis and improvement of design diagrams and mathematical models of vibratory lapping machines
    (Lviv Politechnic Publishing House, 2019) Zakharov Viktor; Kuzio Ihor; Korendiy Vitaliy; Dmyterko Petro
    Problem statement. The development of energy-efficient and high-performance vibratory lapping machines demands the improvement of their design diagrams and calculation techniques. Purpose. The main objectives of this research consist in detailed analysis of existent design diagrams and mathematical models of vibratory lapping machines; designing the three-mass hanger-type structures of such machines providing circular oscillations of laps; derivation of differential equations describing the motion of their oscillatory systems. Methodology. The technique of the research is based on fundamental concepts of engineering mechanics, strength of materials and theory of mechanical vibrations. Findings (results). The improved design diagrams of vibratory lapping machines with circular oscillations of laps are proposed and the corresponding differential equations describing the motion of the working elements are derived. Originality (novelty). The mathematical model of circular oscillations of the three-mass mechanical oscillatory system of vibratory lapping machine is developed. The possibilities of performing the double-side lapping of cylindrical and prismatic parts are considered. Practical value. The results of the performed investiga tions can be used during creating new designs and improving existent structures of vibratory finishing machines for lapping flat surfaces of cylindrical and prismatic parts. Scopes of further investigations. In further investigations, it is necessary to perform the numerical modelling of the system’s motion using the derived differential equations, and to compare the obtained theoretical results with the results of experimental investigations.
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    Structural and kinematic analysis of pantograph-type manipulator with three degrees of freedom
    (Lviv Politechnic Publishing House, 2019) Korendiy Vitaliy; Zinko Roman; Cherevko Yurii
    Problem statement. The processes of development and improvement of autonomous mobile robots are significantly constrained because of the lack of an open-access comprehensive scientific and theoretical framework for calculating and designing of autonomous mobile robotic systems Purpose. The main objective of the paper consists in carrying out kinematic analysis and motion simulation of pantograph-type manipulator with three degrees of freedom. Methodology. The method of closed vector loops is used for deriving the equations of motion of the robot’s manipulator. In order to perform simulation (virtual experiment), the 3D-model of the robot was designed in SolidWorks software. Findings (results). The motion equations of the pantograph-type manipulator are derived, and the graphical dependencies describing the trajectories (paths) of the gripping device are constructed. In order to substantiate the correctness of the derived equations, and of the presented laws of the gripper motion, the corresponding 3D-model of the robot was designed and investigated in SolidWorks software. Scopes of further investigations. In the present paper, there are analysed kinematic parameters of the manipulator motion. While carrying out further investigations, it is necessary to perform its dynamic analysis taking into account all the forces acting upon the elements of the robot, as well as the influence of drives. This will allow to catty out the optimization synthesis of the robots structure, namely the geometrical parameters of the mechanism, operational parameters of drives, etc.
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    Optimization of geometric parameters of a semi-spheroidal solid oxide fuel cell anode using the 3d stress and strain distribution graphs
    (Lviv Politechnic Publishing House, 2019) Kuzio Ihor; Vasyliv Bogdan; Korendiy Vitaliy; Borovets Volodymyr
    The purpose. Determination of radii ranges for cylindrical and convex (semispheroidal) parts of the solid oxide fuel cell (SOFC) semi-spheroidal shape anode based on stress and strain parameters calculated; comparison of 3D graphs of stress/strain distribution in anodes of proposed and spheroidal shapes; substantiation of the semi-spheroidal anode potential to withstand deformation and stress gradient under operational conditions. The research method. The object of research is a solid oxide fuel cell anode of a semi spheroidal shape loaded with a fixing pressure along the closed-loop fixing and with an external gas pressure applied to the anode working surface. Stress and strain distributions in the anode were calculated by finite element analysis using software for calculating three-dimensional tasks Mechanical Desktop 6 Power Pack. Three-dimensional (3D) dependences of stress/strain distribution in anodes of proposed and spheroidal shapes at a variety of R / Rc ratios were plotted. Based on these curves, 3D surfaces of stress distribution along the axis and closed-loop fixing of semi-spheroidal shape anodes were constructed. Results. Three-dimensional curves of the graphic intersections of the surfaces of stress distribution along the axis and closed-loop fixing of semi-spheroidal shape anodes, with their projections on three coordinate planes, were plotted. The curves display the values of balanced stresses depending on geometric parameters. Domains of these curves were also defined. The scientific novelty. The proposed method of building 3D surfaces of stress/strain distribution in anodes depending on their geometric parameters shows for the first time that there exists an area of geometric parameters that allows the appropriate stress level to be reached ensuing safe long-term operation of the semi-spheroidal shape anode. The domain of this area was graphically defined. Based on the plotted isolines showing levels of strain in anodes with the 0.5 mm, 1 mm, and 1.5 mm thick cylindrical parts and a variety of spheroid to cylinder radii ratios, an advantage of a semi-spheroidal shape anode over spheroidal one was substantiated. The practical value. The obtained calculation results and their 3D graphical interpretation can be used in the study of the stress state and, respectively, to evaluate the strength and stiffness of the anode supported SOFCs of various shapes.