Univerzitná knižnica - Vedecké odborné časopisy

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Author: search.filters.author.Piroh, Ondrej

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    Porovnanie optimalizačných algoritmov pri spektrálnom ladení mechanickej sústavy
    (University of Žilina, 2025) Majko, Jaroslav; Deganová, Lucia; Piroh, Ondrej; Minárik, Ján
    This article deals with a comparison of various, gradient-based optimisation algorithms in terms of their accuracy and effectivity. The compared algorithms are the steepest descent method (SDM) and the most well-know quasi-Newton methods. The presented methods were applied to the spectral tuning of a simple two degree of freedom (DOF) mechanism, in order to evaluate their performance. The obtained results were statistically processed and utilised to compare the algorithms, based on their accuracy and overall effectivity. The results show that the quasi-Newton methods are superior to the SDM in terms of both the accuracy and computing time. Moreover, the overall performance of these methods is also significantly less influenced by the selection of starting point. Thus, the obtained results render the quasi-Newton methods as a significantly better choice, compared to the standard SDM.
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    Návrh unikátneho jednoúčelového zariadenia pre skúšky tečenia
    (University of Žilina, 2024) Jakubovičová, Lenka; Piroh, Ondrej; Vaško, Milan; Sága, Milan
    To study the viscoelastic behaviour of polymers, creep test is the most accurate experimental method. This paper presents the engineering design and strength analysis of a special purpose disposable device for performing creep tests of commonly commercially available composite materials, specifically materials fabricated through 3D printing. The device, made of Bosch-Rexroth aluminium profiles, offers flexibility and easy modification to meet different requirements for testing diverse material types. Finite element analysis (FEM) is performed to verify the strength and safety of the device under different load levels. Prior to the actual creep test, a tensile test is performed to obtain material properties such as ultimate strength and maximum elongation. The values obtained are a stepping stone to determine the creep conditions. The results of the finite-element analysis demonstrated the reliability of the equipment for performing the required creep tests and confirmed its suitability for use to perform tests on selected composite materials. The proposed device is also dimensioned for stronger materials in terms of strength, which can be addressed in future studies. The significance of this work lies in providing a cost-effective and customizable solution for creep testing of composite material with wider applications in engineering.