Wyniki wyszukiwania - BazTech

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Influence of Size of Open Hole on Stability of Compressed Plate Made of Carbon Fiber Reinforced Polymer

Wysmulski Paweł, Mieczkowski Grzegorz

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 2

238--247

EN

This manuscript concerns the investigation of the influence of the open hole on stability of the compression plate made of carbon-epoxy composite. Experimental tests carried out on the real plate resulted in a postcritical path from which the critical load value was determined using appropriate approximation method. In parallel, an independent study was carried out based on a numerical analysis using the finite element method (FEM). Investigations were conducted in terms of a linear eigenproblem analysis, from which the value of the bifurcation load was determined for the FEM model of the plate. Its values resulting from the numerical analyses were validated against the experimental results, thus confirming the adequacy of the designed FEM model of the plate. The paper shows that the incremental increase of the hole in the plate monotonically influences the decrease in the critical load of the plate. The largest decrease was observed for the specimen with the largest hole analysed and was 13.5% compared to a plate without a hole. The newness of the paper is the application of interdisciplinary investigation methods to describe the influence of the open hole compression (OHC) on the stability of composite plates. ABAQUS® was used as the tool with which the numerical analyses were realised.

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Evaluation of the influence of the supply pressure on functional parameters of the impulse low-pressure gas-phase injector

Szpica Dariusz, Borawski Andrzej, Mieczkowski Grzegorz, Kusznier Michał, Awad Mohamad M., Sadik Adel M., Sallah Mohammed

Acta Mechanica et Automatica

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2020

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Vol. 14, no. 4

180--185

EN

The article presents research results referring to the influence of supply pressure on the functional parameters of the impulse low-pressure gas-phase injector. The study was done on the original stand for flow test of gas-phase injectors. In the indirect evaluation, with the initial parameters and the length of the forced impulse, the current line, acceleration and pressure sensor courses were used. Apart from the volumetric flow rate, the analysed parameters were the time periods of the injector opening and closing process. Those time segments were composed of response time and opening/closing time, the sum of which gives time of full opening. Functional relationships describing the volumetric flow rate, time of full opening and closing are presented, which are helpful not only in comparative tests of different injectors, but also in modelling the operation of gas injector or algorithms of gas supply control system. The reference to the volumetric flow rate allowed to indicate possible causes of variability of this parameter depending on the supply pressure.

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Criterion for crack initiation from notch located at the interface of bi-material structure

Mieczkowski Grzegorz

Eksploatacja i Niezawodność

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2019

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Vol. 21, no. 2

301--310

EN

The fracture process of bi-material structure with the notch was analysed in this work. For fracture prediction, a criterion based on the Theory of Critical Distances was used. Under analysis were elements made of aluminium alloy and polymer combination (with a various structural notch-tip angle), which then were subjected to the three-point bending test. Values of critical loads resulting from the used hypothesis were compared with values obtained from the experiment. Validation of the selected criterion required defining a qualitative and quantitative description of singular stress fields present around the structural notch-tip area. Therefore, such solutions were obtained and methodology of their determining was discussed.

PL

W pracy przedstawiono wyniki badań dotyczących pękania struktury bi-materiałowej z karbem usytuowanym na interfejsie. Do prognozowania inicjacji procesu pękania zastosowano kryterium oparte na punktowej teorii krytycznych dystansów. Analizowano elementy wykonane ze stopu aluminium i polimerów (PC, PMMA), które poddane były trójpunktowemu zginaniu. Wartości obciążeń krytycznych wynikających z wykorzystanej hipotezy porównano z wartościami uzyskanymi z eksperymentu. Walidacja wybranego kryterium wymagała określania jakościowego i ilościowego opisu osobliwych pól naprężeń, występujących w okolicy wierzchołkowej karbu strukturalnego. W związku z tym, uzyskano takie rozwiązania i omówiono metodykę ich otrzymywania.

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Static electromechanical characteristics of piezoelectric converters with various thickness and length of piezoelectric layers

Mieczkowski Grzegorz

Acta Mechanica et Automatica

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2019

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Vol. 13, no. 1

30--36

EN

The paper presents the analysis of electromechanical characteristics of piezoelectric converters subjected to an electric field and mechanical load. The analyses were performed based on a method consisting implementation of special segments responsible for electrical boundary conditions to a homogeneous beam. Constitutive equations were developed, allowing one to obtain static electromechanical characteristics for piezoelectric actuators with freely defined boundary conditions and geometry. Moreover, based on constitutive equations obtained, a particular solution for cantilever transducer subjected to concentrated force has been developed. The resulting analytical solution was compared with the data available in the literature, and the developed FEM solution. Furthermore, the influence of factors such as relative length, thickness and location of particular piezoelectric layers on electromechanical characteristics of the transducer was defined.