Journal of Engineering Sciences / Журнал інженерних наук
Permanent URI for this collectionhttps://devessuir.sumdu.edu.ua/handle/123456789/34326
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Item Kinematic analysis of 3-PRPPS spatial parallel manipulator with circularly guided base for singularity-free robotic motions(Sumy State University, 2024) Shaik, H.S.Robot manipulators are classified as serial manipulators and parallel manipulators. Parallel manipulators are classified into planar and spatial parallel manipulators (SPMs). The parallel manipulators have moved and fixed platforms connected with serial chains. The parallel manipulators have many linkages, which create a singularity problem. The singular positions of SPMs have also gained substantial attention in various industrial applications due to their intrinsic advantages in precision, flexibility, and load-bearing capabilities. The 3-PRPPS SPM has three prismatic joints, one spherical joint, and one revolute joint. This work changed the fixed base with a circular guided base to avoid singularity issues. The manipulator was modeled with direct kinematic relations. The Jacobian matrix for position and orientation was derived. The workspace was taken as the common area of the three circles, whose radius was the maximum arm length. The position and orientation of the end effector were traced. In the form of the end effector traces, no singularities in the mechanism were observed. The path of the robot manipulator was observed in all the possible positions and orientations. The multi-body simulation was also conducted on the 3-PRPPS manipulator, the main findings of which are presented in this article.Item Determination of chatter-free cutting mode in end milling(Sumy State University, 2024) Petrakov, Y.V.; Ohrimenko, O.A.; Sapon, S.P.; Sikailo, M.O.; Fedorynenko, D.Y.Chatter accompanies the cutting process and is the main obstacle to achieving precision and productivity in milling operations. To reduce the amplitude of vibrations, it was proposed to use a stability lobes diagram (SLD) when assigning cutting modes. The machining system in end milling was represented by a two-mass dynamic model in which each mass has two degrees of freedom. The behavior of such a system was described by a structure with two inputs, in-depth and cutting feed, and a delay in positive feedback on these inputs. A new criterion was applied to design the SLD based on an analysis of the location of the machining system Nyquist diagram on the complex plane. The algorithm for designing a stability chart was developed into an application program, a tool for the technologist-programmer when assigning cutting modes. A method for parameter identification necessary for designing the dynamic system “tool – workpiece” was proposed. The effectiveness of the developed method was proven experimentally when the choice of spindle speed during end milling allows one to reduce the roughness parameter Ra from 3.2 µm to 0.64 µm at the same feed rate of 650 mm/min.Item Computational approach to geometric modeling of plow bodies(Sumy State University, 2024) Yablonskyi, P.; Rogovskii, I.; Sobczuk, H.; Virchenko, G.; Volokha, M.; Vorobiov, O.In this article, a detailed analysis of modern research and publications on the selected subject was carried out related to the computer-variant geometric modeling of the working surfaces of the plow blades. Based on this, a new method of proper design was proposed. The performed scientific investigations aimed to create a flexible, productive, and universal approach for the automated shaping of tillage tools. The accentuated effectiveness of geometric modeling was achieved using a developed special mathematical apparatus adapted for use in the environment of current computer information systems of an engineering profile. The implementation was based on such parametric lines as heterogeneous rational B-splines, which are acceptable in automated design systems. The specified geometric models were characterized by the coverage of a sufficiently large range of plow heads. The indicated means of forming could conveniently adapt to the changing conditions of designing tillage tools suggested by theoretical calculations and practical experiments. The given facts contributed to the multifaceted clarification of the specified information. They also ensured the appropriate integration and the possibility of determining the most rational options among the studied varieties of plow dumps. Simultaneously, the most common group of dumps with cylindrical and other plow working surfaces was considered. The significant role of geometric models for qualitative coordination and the effective combination of many other models (e.g., strength, manufacturing technology, and operation conditions) was emphasized. This was aimed at comprehensive optimization throughout their life cycle, in this case of plows. The proper solution to the presented problems contributed to a successful solution to the actual scientific and applied problem of improving the quality of machinery.Item Induction motor vibrations caused by mechanical and magnetic rotor eccentricity(Sumy State University, 2024) Goroshko, A.V.; Zembytska, M.V.; Paiuk, V.P.Vibration reduction of induction motors is a significant problem that requires effective models for the effects of mechanical and electromagnetic unbalanced forces. This article presents a mathematical model of dynamics for induction motors with rotor mass eccentricity and static and dynamic magnetic eccentricity. The model allows for the influence of the gyroscopic torque of the rotor and considers the elastic-damping characteristics of each of the stator supports and their location. The model has eight degrees of freedom, which makes it possible to simulate transverse and axial vibrations of various designs’ rotors and housings of induction motors. The results of modeling the dynamics for a three-phase squirrel cage induction motor with 11 kW capacity agreed with those obtained by other authors. Simultaneously, new results were also obtained within the research. The simulation results showed that the static magnetic eccentricity causes the appearance of additional critical speed of the motor, and its value decreases in proportion to the growth of the number of pole pairs. The change of the moment of inertia of the motor at a mismatch of the main axis of symmetry of the stator and the rotor axis of rotation allowed for obtaining an actual frequency spectrum of free oscillations, including the rotational motion of the stator. Since the actual static magnetic eccentricity can additionally increase at operating frequencies due to the increase of bearing clearance caused by dynamic unbalanced load, it should be considered in the analysis of unbalanced magnetic pull. The angle of static magnetic eccentricity significantly affects the magnitude of radial vibrations. This feature should also be considered when selecting the locations of balancing weights during the rotor balancing procedure.Item Butane dehydrogenation: Thermodynamic modeling and performance analysis of selected process simulators(Sumy State University, 2024) Barde, E.D.; Oyegoke, T.; Aliyu, A.; Uzochukwu, M.I.; Odih, C.The critical role of process simulation in modern chemical engineering cannot be overstated, with its capacity to facilitate process scale-up, assess alternative designs, and comprehend plant efficiency. This research delves into the performance of three software programs, Cape-Open to Cape-Open (CC), DWSim, and Aspen HYSYS (AH), in modeling butane dehydrogenation. The focus is on their ability to accurately model thermodynamic properties and chemical reaction dynamics. Butane dehydrogenation was evaluated with specific thermodynamic parameters using a Gibbs reactor model with Gibbs minimization. The Soave Redlich-Kwong thermodynamic model was employed to investigate the impact of temperature of 700 °C and pressures of 0.1 MPa and 1.0 MPa on the yield and selectivity of butadiene and butene. The CC and AH simulation results closely agreed with the available experimental data. The consistency of freeware simulators with a commercial simulator was also assessed, with AH serving as the reference standard. It was revealed that CC demonstrates higher consistency with it than DWSim under both low- and highpressure conditions. This study confirms that CC is a reliable process simulator suitable for use in resource-constrained settings where expensive commercial licenses are prohibitive.Item Effect of air intake temperatures on the air-water harvester performance(Sumy State University, 2024) Mirmanto, M.; Nurpatria, N.; Hendra, J.K.During the dry season, some parts of Indonesia experience drought and a clean water crisis, resulting in scarcity and difficulty in drinking water. One of the solutions to solve this problem is to use an air-water harvester machine that produces water from the air. Since the intake air temperature affected the water yield, the article examined the relationship between the engine intake air temperature and the machine’s performance. The study aimed to determine the performance of the air-water harvester machine at various air intake temperatures. The research was carried out experimentally for a refrigerant working fluid R134a. The rotary-type 1/4 PK compressor was used to realize the research. The air temperatures entering the condensing unit varied between 30, 35, and 40 °C. The results showed that the highest average water mass obtained was 0.34 kg at a temperature variation of 30 °C. The highest total heat absorbed by the condensing unit from the air of 184 W occurred at a temperature variation of 40 °C. Overall, an increase in the air intake temperatures allowed for a decrease in the performance of the air-water harvester machine by more than 5 %.Item Methodology for service life evaluation of screens welded structures(Sumy State University, 2024) Shkut, A.P.The methodology of research on welded assemblies for fastening vibrators is based on modern software products, in particular SolidWorks Simulation in combination with SolidWorks Motion and hot spot stress (HSS) technology. It has been determined that the research on welded assemblies using the SolidWorks Education Edition software package is expedient, considering the most unfavorable situation, when there is a lack of fusion of edges. The solid-state model displays a lack of fusion as a gap between the welded parts. The research on the stress-strain state of welded structures using the finite element method shows that when the computational mesh cell size is reduced, the stress increases significantly, indicating the model singularity and the need for further application of the HSS technology. Research has revealed that the maximum stresses occur in those points of the welds where the longitudinal middle rib is connected to the plate and pipe. It has been determined that the service life of welded joints will exceed 2·106 cycles. To assess the accuracy of calculating the dynamic forces arising during the screen operation, the modeling results using the SolidWorks Motion program are compared with those classical methods that use the Lagrange equation of the second kind. It turned out that the calculation error does not exceed 30 %.Item The influence of the design features of the submersible pump rotor on the vibration reliability(Sumy State University, 2024) Маківський, Олексій Сергійович; Makivskyi, Oleksii Serhiiovych; Кондусь, Владислав Юрійович; Kondus, Vladyslav Yuriiovych; Pitel, J.; Сотник, Микола Іванович; Sotnyk, Mykola Ivanovych; Андрусяк, Владислав Олегович; Andrusiak, Vladyslav Olehovych; Полковниченко, Вадим Валентинович; Polkovnychenko, Vadym Valentynovych; Муштай, Максим Валерійович; Mushtai, Maksym ValeriiovychPumping equipment consumes about 20 % of the electrical energy produced by humankind. A significant, even drastic, reduction in the weight and size indicators of pumping equipment leads to a decrease in the cost price and, therefore, competitiveness of such products in the market. Simultaneously, it makes it possible to use more valuable and high-quality construction materials and technologies that improve the reliability of equipment and its energy efficiency, which in turn is a clear step in solving many UN Sustainable Development Goals (SDGs). According to the research results, it was proved that by increasing the frequency of the drive, it is possible to reduce the mass and size indicators of the submersible pump for the needs of the critical infrastructure sector by reducing the number of stages. Mainly, the amplitudes of oscillations near the rotation frequency are 12–22 % and do not exceed 35 % of the gaps in the seals, as required by the available international standards to ensure the guaranteed vibration reliability of the pump. Overall, using a bearingless support design will significantly increase the reliability of the developed pump.Item The distribution pattern of machining errors on woodworking machine tools(Sumy State University, 2023) Pylypchuk, M.I.; Dziuba, L.F.; Mayevskyy, V.O.; Kopynets, Z.P.; Taras, V.I.The article aims to develop a methodology for calculating and predicting the distribution patterns of wood machining errors to assess the operating conditions of the machine tool according to the technological accuracy criterion. It was analytically proven and experimentally confirmed that Weibull’s law accurately describes the distribution pattern of machining errors on woodworking machines. Based on the results of experimental studies of the accuracy of machining on machines for lengthwise sawing and plano-milling of wood, it was found that the primary indicator of the Weibull distribution law is a shape parameter that takes values within 1.89–3.11. The computational algorithm was developed for statistical modeling of the pattern of the distribution of machining errors according to the Weibull distribution law. It allows for determining the main parameters of the error distribution law and evaluating the operating conditions for the machine tool according to the technological accuracy criterion. The statistical modeling results for the distribution pattern of machining errors are correlated with the experimental data with an accuracy of up to 5 %, which confirms the reliability of the obtained simulation results. The developed approach also minimizes the restoration cost for the machine’s operability.Item Cutting forces simulation for end milling(Sumy State University, 2023) Petrakov, Y.V.; Ohrimenko, O.A.; Sikailo, M.O.; Myhovych, A.V.The cutting force in end milling is the essential perturbation of the machining system that limits the productivity of the process. Therefore, forecasting the cutting force when assigning the processing mode and the geometry of the allowance layer to be cut is an urgent task that requires an operational tool for its solution. The method of calculating the cutting force is presented, based on a mechanistic approach, when the geometric ratios of the cutter blades’ positions on the sweep determine the thickness of the undeformed chip. The developed algorithm calculates the cutting force by double integration, first by the length of the cutting edge and then by the number of such edges. The algorithm also allows the simulating of the outrun of the mill on the cutting force and its components. The created application program visualizes the simulating process by oscillograms of the cutting force components for both up and down milling. Experimental studies, in general, proved the adequacy of the developed modeling method. The created program is a tool for operational forecasting of the cutting force during the technological preparation of the end milling process in production.
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