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    Wyświetlanie 1-8 z 8
    Tytuł:
    Wave propagation in piezoelectric rings with rectangular cross-sections
    Autorzy:
    Zhang, X.
    Wang, Y.
    Chen, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/279995.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    piezoelectric rings
    orthogonal polynomial
    guided wave
    dispersion curves
    Opis:
    The ring ultrasonic transducers are widely used in the ocean engineering and medical fields. This paper employs an extended orthogonal polynomial approach to solve the guided wave propagation in two-dimensional structures, i.e. piezoelectric rings with rectangular cross- -sections. The extended polynomial approach can overcome the drawbacks of the conven- tional orthogonal polynomial approach which can be used to solve wave propagation in one-dimensional structures. Through numerical comparison with the available results for a rectangular aluminum bar, the validity of the present approach is illustrated. The dispersion curves and displacement and electric potential distributions of various rectangular piezo- electric rings are calculated, and the effects of different radius to thickness ratios, width to height ratios and polarizing directions on the dispersion curves are illustrated.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2015, 53, 3; 673-682
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An application of stiffness matrix method to determining of dispersion curves for arbitrary composite materials
    Autorzy:
    Barski, M.
    Pająk, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/244021.pdf
    Data publikacji:
    2016
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    SHM system
    multi-layered composites
    elastic waves
    dispersion curves
    stiffness matrix method
    Opis:
    Nowadays multi-layered composite material is very often applied in different kind of structures, like aircrafts, boats or vehicles. Parts of structures, which are made of these materials, are significantly lighter in comparison with traditional materials, like aluminum or steel alloys. On the other hand, the process of damage creation and evolution in the case of composites is much more complex. Moreover, the damages, which are characteristic for multi-layered materials (matrix cracking, fibre breakage, delaminations), are very difficult to detect at early stage of creation. Hence, there is a need to develop the advanced methods to detect them without destroying tested composite element. One of them is based on analysis of elastic wave propagation through the composite structure. Unfortunately, elastic waves possess strongly dispersive character. Thus, it is necessary to determine dispersion curves for investigated material before the tests in order to appropriate interpretation of received dynamic response of structure. In the case of arbitrary composite materials, it is rather challenging task. In the present article the relatively new, analytical method is applied, namely stiffness matrix method. The fundamental assumptions and the theoretical formulation of this method are discussed. Next numerical examples are presented, namely the dispersion curves are determined for the single orthotropic lamina and multi-layered 'quasi - isotropic' composite plate. The studied plates are made of glass fibres and epoxy resin. In the case of single lamina, the dispersion curves are determined in the parallel, perpendicular and arbitrary direction of waves propagation with respect to the fibre direction. In the case of multi-layered plates, the dispersion curves are computed for one arbitrary direction. Additionally, the phase and group velocities for fundamental modes and fixed excitation frequency are estimated in all directions of waves propagation.
    Źródło:
    Journal of KONES; 2016, 23, 1; 47-54
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determination of dispersion curves for composite materials with the use of stiffness matrix method
    Autorzy:
    Barski, M.
    Pająk, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/386825.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
    Tematy:
    structural health monitoring
    layered composite materials
    guided waves
    dispersion curves
    stiffness matrix method
    Opis:
    Elastic waves used in Structural Health Monitoring systems have strongly dispersive character. Therefore it is necessary to determine the appropriate dispersion curves in order to proper interpretation of a received dynamic response of an analyzed structure. The shape of dispersion curves as well as number of wave modes depends on mechanical properties of layers and frequency of an excited signal. In the current work, the relatively new approach is utilized, namely stiffness matrix method. In contrast to transfer matrix method or global matrix method, this algorithm is considered as numerically unconditionally stable and as effective as transfer matrix approach. However, it will be demonstrated that in the case of hybrid composites, where mechanical properties of particular layers differ significantly, obtaining results could be difficult. The theoretical relationships are presented for the composite plate of arbitrary stacking sequence and arbitrary direction of elastic waves propagation. As a numerical example, the dispersion curves are estimated for the lamina, which is made of carbon fibers and epoxy resin. It is assumed that elastic waves travel in the parallel, perpendicular and arbitrary direction to the fibers in lamina. Next, the dispersion curves are determined for the following laminate [0°, 90°, 0°, 90°, 0°, 90°, 0°, 90°] and hybrid [Al, 90°, 0°, 90°, 0°, 90°, 0°], where Al is the aluminum alloy PA38 and the rest of layers are made of carbon fibers and epoxy resin.
    Źródło:
    Acta Mechanica et Automatica; 2017, 11, 2; 121-128
    1898-4088
    2300-5319
    Pojawia się w:
    Acta Mechanica et Automatica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modeling the propagation of ultrasonic guided waves in a composite plate by a spectral approximation method
    Autorzy:
    Zitouni, Ismaine
    Rhimini, Hassan
    Chouaf, Abdelkerim
    Powiązania:
    https://bibliotekanauki.pl/articles/38896621.pdf
    Data publikacji:
    2023
    Wydawca:
    Instytut Podstawowych Problemów Techniki PAN
    Tematy:
    guided waves
    spectral method
    dispersion curves
    graphite epoxy composite
    acoustic power
    normalized displacement.
    Opis:
    Graphite-epoxy composites have been able to meet the multiple requirements of the space industry. However, the radiation from the spatial environment and non-perfect adhesion between the fibers and the matrix can lead to the appearance of imperfections. To handle this, we use non-destructive testing by ultrasonic guided waves known for its high accuracy in detecting defects. In this article, we study the propagation of ultrasonic guided waves in a graphite-epoxy composite plate by the spectral method. First, the mathematical formalism is explained for modeling guided waves in the composite material. Next, we plot the dispersion curves of the composite plate in different orientations of the fibers with a MATLAB program and the results are compared with those of the DISPERSE software. These give us information on the modes that propagate in the structure. We elaborate and explain a technique based on displacement symmetry to distinguish between the different modes. A discussion based on time-saving and accuracy is established to show the advantages of the method. The second part of our paper consists in giving a physical meaning to the spectral displacements normalized in amplitude. We propose to normalize the spectral eigenvectors by the acoustic power. We plot the displacement and stress profiles of the guided modes and we compare our results to the analytical ones. Perfect correspondence is found, indicating the accuracy of the approach developed. In addition, a study of the vibrational state in the composite plate is established for Lamb and horizontal shear modes at a specific frequency.
    Źródło:
    Engineering Transactions; 2023, 71, 2; 213-227
    0867-888X
    Pojawia się w:
    Engineering Transactions
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical simulation of fundamental elastic wave modes coupling in composite plates
    Autorzy:
    Barski, Marek
    Stawiarski, Adam
    Chwał, Małgorzata
    Augustyn, Marcin
    Powiązania:
    https://bibliotekanauki.pl/articles/24201983.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    shear horizontal wave mode
    symmetric wave mode
    dispersion curves
    finite element method
    fala SH
    fala symetryczna
    krzywa dyspersji
    metoda elementów skończonych
    Opis:
    In the case of the piezoelectric actuators of the cube-shaped installed symmetrically and perfectly bonded on both external surfaces of the plate-like structures, the symmetric and shear horizontal elastic wave modes are excited at the same time. The current work concerns the numerical simulation of the coupling of the above-mentioned elastic wave modes in a composite plate of angle ply configuration. In the first step, the dispersion curves for all studied composite configurations are estimated. Next, for the arbitrary chosen fixed frequency of the excitation, finite element simulations are performed. As a result of these simulations, the group velocities of the observed elastic modes are estimated. Next, the appropriate wave modes are identified by the comparison of the group velocities obtained from the analysis of the dispersion curves and from the simulations. In the cases for which the identification is possible, a good agreement between analytical and simulation results is observed.
    Źródło:
    Vibrations in Physical Systems; 2023, 34, 1; art. no. 2023120
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of the configuration of the fiber-metal laminates on the dispersion relations of the elastic wave modes
    Autorzy:
    Barski, Marek
    Muc, Aleksander
    Stawiarski, Adam
    Powiązania:
    https://bibliotekanauki.pl/articles/2146565.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    FML
    fiber metal laminates
    GLARE
    elastic wave modes
    dispersion curves
    stiffness matrix method
    laminaty metalowo-włókniste
    mody fal sprężystych
    krzywa dyspersji
    metoda macierzy sztywności
    Opis:
    The current work is devoted to the determination of dispersion curves for elastic wave modes. The studied elastic waves propagate across metal-fiber hybrid composites. In order to solve the problem, special software has been developed with the use of C++. This software works with the MS Windows operating system and the proposed solution is based on the multi-threading mechanism. It makes possible to significantly speed up the calculations. The relatively new approach is used namely the stiffness matrix method. At the very beginning, the dispersion curves are determined for the traditional composite materials of cross-ply configuration, for which the layers are made of glass fiber/epoxy resin and carbon fiber/epoxy resin. The impact of the total number of layers on the dispersion curves is investigated. Next, the influence of the thickness of the layers, which are made of aluminum alloy, on the dispersion characteristic is studied. In the second case, it is assumed that the total thickness of the composite material wall for all cases is identical.
    Źródło:
    Vibrations in Physical Systems; 2020, 31, 2; art. no. 2020202
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Influence of Impeller Geometry on the Gas Bubbles Dispersion in Uro-200 Reactor – RTD Curves
    Wpływ rodzaju wirnika na dyspersję pęcherzyków gazowych w reaktorze uro-200 – krzywe mieszania
    Autorzy:
    Saternus, M.
    Merder, T.
    Pieprzyca, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/353628.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    aluminium refining
    gas dispersion
    physical modelling
    RTD curves
    rafinacja aluminium
    dyspersja gazu
    modelowanie fizyczne
    krzywe RTD
    Opis:
    URO-200 reactor belongs to batch reactors used in refining process of aluminium and its alloys in polish foundries. The appropriate level of hydrogen removal from liquid aluminium can be obtained when the mixing of inert gas bubbles with liquid metal is uniform. Thus, the important role is played by the following parameters: flow rate of refining gas, geometry of the impeller, rotary impeller speed. The article presents the results of research conducted on physical model of URO-200 reactor. The NaCl tracer was introduced to water (modelling liquid aluminium) and then the conductivity was measured. Basing on the obtained results the Residence Time Distribution (RTD) curves were determined. The measurements were carried out for two different rotary impellers, flow rate equaled 5, 10, 15 and 20 dm3/min and rotary impeller speed from 250 to 400 rpm every 50 rpm.
    Reaktor URO-200 jest reaktorem cyklicznym stosowanym powszechnie w Polsce do procesu rafinacji aluminium i jego stopów. Odpowiedni stopień usuwania wodoru z ciekłego aluminium uzyskuje się wówczas, gdy wymieszanie ciekłego metalu z pęcherzykami gazu obojętnego jest równomierne. Ważną rolę odgrywają takie parametry procesowe jak: natężenie przepływu gazu, kształt wirnika oraz prędkość obrotowa rotora. W artykule przedstawiono wyniki badań w oparciu o model fizyczny reaktora URO-200. Mierzono konduktywność roztworu wodnego (modelującego ciekłe aluminium), do którego wprowadzano znacznik NaCl. W oparciu o otrzymane wyniki wykreślono krzywe mieszania RTD (Residence Time Distribution). Pomiary prowadzono dla dwóch różnych wirników przy natężeniu przepływu gazu 5, 10, 15 i 20 dm3/min oraz przy obrotach wirnika 250, 300, 350 i 400 obr/min.
    Źródło:
    Archives of Metallurgy and Materials; 2015, 60, 4; 2887-2894
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Probabilistyczny model dyskretnego rozkładu gęstości warstw w łożu osadzarki
    Probabilistic Model of Discrete Distribution of Layer Density in the Jig Bed
    Autorzy:
    Glowiak, Stanisław
    Powiązania:
    https://bibliotekanauki.pl/articles/318347.pdf
    Data publikacji:
    2020
    Wydawca:
    Polskie Towarzystwo Przeróbki Kopalin
    Tematy:
    wzbogacanie węgla kamiennego
    osadzarka
    modelowanie osadzania
    krzywe rozdziału
    rozpraszanie ziaren
    hard coal enrichment
    jig
    modeling of the jig operation
    dispersion of grains
    separation curves
    Opis:
    W artykule przedstawiono szczegółowy opis probabilistycznego modelu dyskretnego rozkładu gęstości warstw w łożu osadzarki opracowanego na podstawie założeń przedstawionych w pracy (Głowiak 2019). Opis ten zawiera wszystkie wzory opisujące zależności istniejące w tym modelu. Podano także te szczegóły założeń, których jasne przedstawienie korzystniej było połączyć ze szczegółami obliczeń. Wykonany model wykorzystano do obliczeń rozkładu gęstości cząstek w poszczególnych warstwach. Obliczenia te wykazują istnienie znacznych różnic w tych rozkładach w stosunku do innych znanych modeli. Także całościowy obraz procesu wzbogacania w osadzarce przyjmowany na podstawie dotychczasowych badań eksperymentalnych i rozważań teoretycznych znacznie różni się od obrazu wynikającego z przedstawianego modelu. Różnice te okazują się ważne także dla praktyki wzbogacania węgla wskazując wyraźnie na wybór kierunku modernizacji osadzarek istotnie różny od tendencji aktualnie panujących wśród konstruktorów tych maszyn. Z przedstawionego modelu wynika także niepoprawność obecnie używanych obliczeń do przewidywania wyników wzbogacania z zastosowaniem krzywych rozdziału spowodowaną głównie dowolnością wyboru gęstości rozdziału, która w rzeczywistym procesie osadzania jest znacznie ograniczona przez gęstości tworzących się warstw. Przedstawiony model pokazuje także, że matematyczna aproksymacja krzywych rozdziału przyjmowana w tych obliczeniach nie jest poprawna.
    Presented paper is the detailed description of probabilistic model of discrete distribution of layer density in the jig bed, developed on the basis of its assumptions presented in the paper (Głowiak 2019). This elaboration contains all formulas describing the relationships existing in this model. The details of the assumptions were also given, which clear presentation was more advantageous to combine with the details of the calculations. The model was used to calculate the density distribution of particles in individual layers. These calculations show that there are significant differences in these distributions compared to other known models. Also the overall picture of the enrichment process in the jig adopted on the basis of previous experimental research and theoretical considerations is significantly different from the picture resulting from the presented model. Observed differences also turn out to be important for the practice of coal enrichment, indicating clearly the choice of the direction of jigs modernization significantly different from the trends currently prevailing among the designers of these machines. The presented model shows also incorrectness of currently used calculations to predict separation results using separation curves mainly due to the free choice of separation density. The choice of separation density in the actual jig operation process is significantly limited by the densities of the layers formed. The presented model shows that the mathematical approximation of the separation curves in the currently used calculation is not correct.
    Źródło:
    Inżynieria Mineralna; 2020, 1, 1; 187-198
    1640-4920
    Pojawia się w:
    Inżynieria Mineralna
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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