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    Wyświetlanie 1-5 z 5
    Tytuł:
    An investigation of nonlinear tangential contact behaviour of a spherical particle under varying loading
    Autorzy:
    Zabulionis, D.
    Kacianauskas, R.
    Markauskas, D.
    Rojek, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/201333.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    discrete element method
    tangential elastic-frictional contact
    incrementally linear constitutive relationship
    stick-sliding switch
    Opis:
    An analytical and numerical study of the tangential contact of a spherical particle under varying combined normal-tangential loading is presented. The normal and tangential contact is described by the Hertz and regularized Coulomb laws. This study is focused on the analysis of the tangential displacement of the particle’s contact point under variable normal force and reevaluation of the procedures for calculation of the tangential force. The incremental displacement-driven and force-driven constitutive relationships are developed. The importance of an adequate numerical treatment of the tangential component of the contact force is shown for the slide mode, and the recommendations for its evaluation are proposed. The performance of the algorithm is demonstrated by solving the problem of the oblique impact of the spherical particle on the wall. The suggested methodology allows us to analyse the elastic and sliding effects of the tangential interaction more precisely than existing methodologies. Besides, the issue of the direction of the tangential force, when the Coulomb limit is reached, was reconsidered in one-dimensional case by taking three versions of the unit direction vector, which are based on the tangential elastic displacement, tangential stick force, and tangential relative velocity of the contact point of the particle.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 2; 265-278
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adaptation of the machine to the new geological conditions – excavation unit redesign and optimization
    Autorzy:
    Andruszko, Jakub
    Moczko, Przemyslaw
    Pietrusiak, Damian
    Powiązania:
    https://bibliotekanauki.pl/articles/2173623.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    dredger
    rigid body dynamics
    3D scanning
    discrete element method
    finite element method
    pogłębiarka
    dynamika ciała sztywnego
    skanowanie 3D
    metoda elementów dyskretnych
    metoda elementów skończonych
    Opis:
    The paper presents and sums up the research and technical aspects of the modernization of the cutting tool of the dredger. Improper adjustment of the cutting elements not adjusted to the characteristics of excavated material is not an uncommon situation, causing versatile geological conditions. Relocation of the machines from one pit to another may result in the significant influence on the excavation process (wear, output, etc.). Common practice is the field try and error approach to obtain desired machine performance. In the paper authors present the approach with aid of cutting-edge technologies. Coupled DEM and kinematic simulations supported by the reverse engineering technologies of laser scanning were the fundamental drivers for final adjustments of the cutting tool at its present operational conditions.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 3; art. no. e137122
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adaptation of the machine to the new geological conditions – excavation unit redesign and optimization
    Autorzy:
    Andruszko, Jakub
    Moczko, Przemyslaw
    Pietrusiak, Damian
    Powiązania:
    https://bibliotekanauki.pl/articles/2128171.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    dredger
    rigid body dynamics
    3D scanning
    discrete element method
    finite element method
    pogłębiarka
    dynamika ciała sztywnego
    skanowanie 3D
    metoda elementów dyskretnych
    metoda elementów skończonych
    Opis:
    The paper presents and sums up the research and technical aspects of the modernization of the cutting tool of the dredger. Improper adjustment of the cutting elements not adjusted to the characteristics of excavated material is not an uncommon situation, causing versatile geological conditions. Relocation of the machines from one pit to another may result in the significant influence on the excavation process (wear, output, etc.). Common practice is the field try and error approach to obtain desired machine performance. In the paper authors present the approach with aid of cutting-edge technologies. Coupled DEM and kinematic simulations supported by the reverse engineering technologies of laser scanning were the fundamental drivers for final adjustments of the cutting tool at its present operational conditions.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 3; e137122, 1--9
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Damage localization in truss girders by an application of the discrete wavelet transform
    Autorzy:
    Knitter-Piątkowska, Anna
    Kawa, Olga
    Guminiak, Michał Jan
    Powiązania:
    https://bibliotekanauki.pl/articles/2204501.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    truss structures
    damage localization
    finite element method
    discrete wavelet transform
    konstrukcja kratownicowa
    lokalizacja uszkodzeń
    metoda elementów skończonych
    dyskretna transformata falkowa
    Opis:
    The paper demonstrates the potential of wavelet transform in a discrete form for structural damage localization. The efficiency of the method is tested through a series of numerical examples, where the real flat truss girder is simulated by a parameterized finite element model. The welded joints are introduced into the girder and classic code loads are applied. The static vertical deflections and rotation angles of steel truss structure are taken into consideration, structural response signals are computed at discrete points uniformly distributed along the upper or lower chord. Signal decomposition is performed according to the Mallat pyramid algorithm. The performed analyses proved that the application of DWT to decompose structural response signals is very effective in determining the location of the defect. Evident disturbances of the transformed signals, including high peaks, are expected as an indicator of the defect existence in the structure. The authors succeeded for the first time in the detection of breaking the weld in the truss node as well as proved that the defect can be located in the diagonals.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2023, 71, 1; art. no. e144581
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mechanical fault detection in rotating electrical machines using MCSA-FFT and MCSA-DWT techniques
    Autorzy:
    Bessous, N.
    Sbaa, S.
    Megherbi, A. C.
    Powiązania:
    https://bibliotekanauki.pl/articles/200283.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    motor current signature analysis
    MCSA
    discrete wavelet transform
    DWT
    rolling element bearing faults
    rotor eccentricity
    stator current spectrum
    dyskretna transformata falkowa
    uszkodzenia łożysk tocznych
    widmo prądu stojana
    Opis:
    This paper presents mechanical fault detection in squirrel cage induction motors (SCIMs) by means of two recent techniques. More precisely, we have analyzed the rolling element bearing (REB) faults in SCIM. Rolling element bearing faults constitute a major problem among different faults which cause catastrophic damage to rotating machinery. Thus early detection of REB faults in SCIMs is of crucial importance. Vibration analysis is among the key concepts for mechanical vibrations of rotating electrical machines. Today, there is massive competition between researchers in the diagnosis field. They all have as their aim to replace the vibration analysis technique. Among them, stator current analysis has become one of the most important subjects in the fault detection field. Motor current signature analysis (MCSA) has become popular for detection and localization of numerous faults. It is generally based on fast Fourier transform (FFT) of the stator current signal. We have detailed the analysis by means of MCSA-FFT, which is based on the stator current spectrum. Another goal in this work is the use of the discrete wavelet transform (DWT) technique in order to detect REB faults. In addition, a new indicator based on the MCSA-DWT technique has been developed in this study. This new indicator has the advantage of expressing itself in the quantity and quality form. The acquisition data are presented and a comparative study is carried out between these recent techniques in order to ensure a final decision. The proposed subject is examined experimentally using a 3 kW squirrel cage induction motor test bed.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 3; 571-582
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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