Browsing by Author "Kovalenko, Iaroslav"

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    CERAMIC 3D PRINTING: COMPARISON OF SLA AND DLP TECHNOLOGIES
    (MM SCIENCE, PRIPOCNI 1519-10A, PRAGUE 10, 10100, CZECH REPUBLIC, 2020-06-01) Truxová, Veronika; Šafka, Jiří; Seidl, Martin; Kovalenko, Iaroslav; Voleský, Lukáš; Ackermann, Michal
    Complex ceramic parts tend to be difficult or even impossible to produce by conventional methods. Therefore, the 3D printing technologies have started to spread widely in the area of ceramic parts production. The aim of this paper is to compare the efficiency of Stereolithography and Digital Light Processing technologies in 3D printing of ceramic parts. Firstly, indicative chemical analysis was performed on a chosen ceramic suspension. Secondly, sample parts of different shapes were designed and printed using both technologies. Next, printed samples were analyzed using thermogravimetric and optical analyses. Finally, printed parts were debound and sintered, and final ceramic parts were consequently reanalyzed. Both technologies show the best results in the printing of thin-walled and hollow models. The DLP was significantly faster, especially when the printing platform was close to full occupancy.
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    Effect of UV radiation by projectors on 3D printing
    (Department of Manufacturing Systems and Automation, Technical University of Liberec, Studentska 1402/2, Liberec, Czech Republic, 2017-02-15) Kovalenko, Iaroslav; Garan, Maryna
    Polymers that solidify under light radiation are commonly used in digital light processing (DLP) 3D printing. A wide range of photopolymers use photoinitiators that react to radiation in range of ultraviolet (UV) wavelength. In the present study we provided measurement of radiant fluence in the UV wavelength range from 280 nm to 400 nm for two data projectors and compared effect of radiation on quality of 3D printing. One projector is commonly used DLP projector with high energy lamp. Second one is an industrial projector, in which RGB light emitting diodes (LEDs) are replaced by UV LEDs with wattage at the level of 3.6 % of the first one. Achieved data confirmed uneven distribution of radiant energy on illuminated area. These results validate, that undesired heating light causes internal stress inside built models that causes defects in final products. © The Authors, published by EDP Sciences, 2017.
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    Examining the relationship between forces during stereolithography 3D printing and geometric parameters of the model
    (EDP Sciences, 2016-01-01) Kovalenko, Iaroslav; Garan, Maryna; Shynkarenko, Andrii; Zelený, Petr; Šafka, Jiří
    In the case of stereolithography 3D printing technology, detaching formed model from the tank with photopolymer is a lengthy process. Forces, which appear during removing of solid photopolymer layerformed in stereolithography 3D DLP printer, can destroy the built model. In this article the detachment force is measured, obtained results arestatistically analyzed and relation between detach force, area of produced layer and thickness of the layer are verified. Linear dependence between detach force and built area is determined. On the other hand, relation between detach force and thickness of the layer is not confirmed. © 2016 Owned by the authors, published by EDP Sciences.
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    Experimental shrinkage study of ceramic DLP 3D printed parts after firing green bodies in a KILN
    (2019-01-01) Kovalenko, Iaroslav; Ramachandran, Yuvaraj; Garan, Maryna
    The objective of this work was to investigate dimensional parameters of 3D printed parts from glass ceramic photopolymer before and after debinding and sintering in a kiln. During experiments batches of green bodies were printed with different layer thickness and curing strategy. We used 3D printer with ultraviolet LED as a light power source. The peak of intensity of the UV LED was in the range from 385 to 405 nm. DLP projector from Texas Instruments was used for mask projection. After printing, each batch of green bodies was cleaned and post-cured in a UV chamber. Then their dimensions were measured, overgrowth of each sample was calculated. The next stage of the experiment was kiln firing according to special firing schedule. Dimensions of final parts were measured again, and their shrinkage was calculated. The experiment proved high influence of printing parameters on the overgrowth of models and almost no influence on shrinkage of parts after firing.
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    Parameter Estimation in Linear Dynamic Systems using Bayesian networks
    (Institute of Electrical and Electronics Engineers Inc., 2019-06-01) Garan, Maryna; Verron, Sylvain; Kovalenko, Iaroslav; Modrlak, Osvald; Lepšík, Petr
    Parameter estimation in models of dynamic systems is a common preliminary procedure in control, monitoring, fault detection and diagnosis. A range of tools to fulfill this task has been constantly expanded with new additions to meet the increasing demands of modern technological processes. This article proposes the use of Bayesian networks to estimate the parameters of linear dynamic systems described by a state-space model. The proposed approach is used for system identification of two simulated dynamic systems. The parameters are estimated using a learning function for Bayesian networks from Bayes Net Toolbox for Matlab. The results indicate that Bayesian networks can be used as a system identification tool that can compete with conventional methods. However, the approach requires further research aiming to increase convergence of estimates and eliminate numerical problems.
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    Systém pro řízení pohybu angulárního robota
    (Technická Univerzita v Liberci, 2013-01-01) Kovalenko, Iaroslav; Moučka, Michal
    Obsahem této práce je návrh systému pro řízení pohybu laboratorního modelu angulárního robota, realizace řídicí elektroniky a výroba desky plošných spojů pro uskutečnění navrţeného řešení. V práci je podrobně popsán postup výroby řídicího systému s popisem základních modulů, včetně principů jejich práce v daném systému. Dále je velice podrobně popsané sériové rozhraní pro ovládání robota z jiného přístroje. V závěru práce jsem uvedl hlavní činnosti a moţnosti daného systému a jeho klady pro řízení daného angulárního robota.
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    Vývoj prototypu 3D tiskárny na fotopolymery
    (2018-10-30) Kovalenko, Iaroslav; ; Pokorný Přemysl, prof. Ing. CSc. Skolitel : 55388
    Aditivní výroba je velice rychle se rozvíjející oblast inženýrství, která se postupně přestává používat výhradně pro prototypování. Historicky první 3D tiskárny stavěné na vytvrzování fotopolymerů dostaly nový impulz s rozvojem projekčních technologií. Možnost promítání celé tisknuté vrstvy najednou odstranila největší nevýhodu tiskáren tohoto typu, a to neskutečně dlouhou dobu tisku.Představená disertační práce se zabývá vývojem a stavbou 3D tiskárny na zpracování fotopolymerních materiálů, která kontroluje stav tisku v reálném čase. Tiskárna pracuje na principu technologie generování obrazu DLP projektorem. Ultrafialové záření ze zdroje světelné energie prochází DMD deskou a formuje obraz vrstvy tištěného modelu. Obraz se promítá na tenkou vrstvu fotopolymeru, která se působením UV záření polymerizuje. Platforma, na níž se vytváří model, se v každém kroku posouvá o jednu vrstvu modelu nahoru. Platforma je zavěšena na konzolu, která je poháněna servopohonem s krokovým motorem se zpětnou vazbou a kuličkovým šroubem. Mezi konzolou a platformou je zabudovaný tenzometrický siloměr, který neustále měří sílu vznikající při odlepování vytvrzené vrstvy modelu ode dna nádrže s fotopolymerem. Při vzniku neodpovídajícího silového průběhu během tisku hlásí řídící systém chybu a přerušuje tisk. Tím se snižují časové a materiálové náklady na tisk.Tiskárna, postavená v rámci této práce, se používá pro tisk keramických a kompozitních materiálů na základě fotopolymerů. Je zapojena do výzkumných projektů zabývajících se tiskem ze skla, kovu a keramiky. Na tiskárně probíhají testy metod a způsobů tisku různorodých fotopolymerních materiálů.