Періодичні видання СумДУ
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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.Item Effect of Temperature on the Performance of CGS/CIGS Tandem Solar Cell(Sumy State University, 2023) Elbar, M.; Tobbeche, S.; Chala, S.; Saidani, O.; Kateb, M.N.; Serdouk, M.R.The CGS and CIGS being promising materials for large scale photovoltaic applications, the effect of temperature on the electrical parameters of a CGS/CIGS tandem solar cell has been investigated in this work. The copper gallium diselenide (CGS) and copper indium gallium diselenide (CIGS) structures as topcell and bottom-cell respectively, were numerically simulated under AM1.5G spectral illumination using the two-dimensional device simulator Silvaco-Atlas. The temperature dependency of the solar cell’s characteristics was investigated in the temperature range from 300 to 400 K at intervals of 20 K. The simulation results show the density current (Jsc) slightly increases whereas the open-circuit voltage (Voc) and fill factor (FF), conversion efficiency (ƞ) decreases with the increase in temperature. The tandem cell operating temperature efficiency was found to be (– 0.34 %/K), which is slightly higher than that of CGS solar cell (– 0.29 %/K), but markedly better than that of CIGS solar cell (– 0.41 %/K).Item Transient 3D Thermomechanical Simulation of the Frictional Contact of the Pin-on-Disc System(Sumy State University, 2022) Abboudi, A.; Boulahrouz, S.; Mansouri, K.Тертя генерує розсіювання тепла, що супроводжується нагріванням системи pin-on-disc, у деяких випадках це нагрівання може впливати на термомеханічні властивості системи. У статті представлено перехідне тривимірне чисельне моделювання за допомогою програмного забезпечення COMSOL multiphysics термомеханічної поведінки під час динамічного контакту системи pin-on-disc. Термомеханічна модель тертя запозичена з літератури. Обговорюється вплив затримки контакту [0..10] секунд, зміни навантаження на pin [1..4] МПа та зміни швидкості диска [10..15] м/с. Результати роботи показують, що збільшення затримки контакту призводить до швидкого підвищення температури контактної зони в перші секунди, а починаючи з четвертої секунди, збільшення дуже незначне і стає постійним через поширення тепла шляхом провідності у вільних ділянках системи pin-on-disc. Вплив поступового збільшення навантаження на pin є більш помітним, ніж вплив швидкості диска на термомеханічну поведінку системи pin-on-disc.Item Dimet Laval nozzle expansion section analysis and optimization(Sumy State University, 2021) Kun, T.; Jie, H.W.; Markovych, S.; Wang, Y.The cold spray technology mainly accelerates the powder in the Laval nozzle by gas, ensuring that the powder has a greater velocity at the exit of the Laval nozzle, and achieving high-efficiency deposition on the substrate, thereby obtaining a better performance of the deposition coating. The article uses numerical simulation to study the influence of the length of the expansion section of the Dimet Laval nozzle on the acceleration effect of Al powder. The results show that the length of the expansion section of the nozzle is an essential factor affecting the velocity of the Al powder at the nozzle outlet. Through analysis, it can be known that the pressure inlet range of the Dimet Laval nozzle is 1.0 MPa, and the length of the expansion section is about 210 mm, which can ensure that the Al powder has a better acceleration effect in the nozzle and has a better velocity at the nozzle outlet. It is recommended that the joints between the small sections of the nozzle expansion section should be kept as smooth as possible so that the accelerating effect of the accelerating gas on the Al powder is more uniform and stable.