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    Wyświetlanie 1-7 z 7
    Tytuł:
    The effect of added point masses on the geometrically non-linear vibrations of SCSC rectangular plates
    Autorzy:
    Hamdani, Mustapha
    El Kadiri, Mounia
    Benamar, Rhali
    Powiązania:
    https://bibliotekanauki.pl/articles/2096183.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
    Tematy:
    SCSC rectangular plates
    added mass
    nonlinear free vibration
    nonlinear forced vibration
    swobodne drgania nieliniowe
    płyta prostokątna
    nieliniowe drgania wymuszone
    Opis:
    A point mass added to a plate may have a significant effect on its linear and nonlinear dynamics, including frequencies, mode shapes and the forced response to external loading. In the present paper, a simply supported clamped simply supported clamped rectangular plate (SCSCRP) carrying a point mass is examined. The expressions for the kinetic, linear and non-linear strain energies are derived by taking into account the effect of the added mass on the kinetic energy and the effect of the membrane forces induced by the non-linearity on the strain energy. The discretization of these expressions makes the mass tensor, the linear and non-linear rigidity tensors appear in a non-linear algebraic multimode amplitude equation, the iterative solution of which permit to obtain, in the neighborhood of the first non-linear mode, the basic SCSCRP function amplitude dependent contribution coefficients. Nonlinear frequency response functions have been obtained for the first time, based on an iterative numerical solution in each case of the associated complete set of nonlinear algebraic equations. Such new results are useful for a better qualitative understanding allowing an optimal dynamic design of the rectangular plates with added masses.
    Źródło:
    Diagnostyka; 2022, 23, 2; art. no. 2022206
    1641-6414
    2449-5220
    Pojawia się w:
    Diagnostyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of the associated stress distributions to the nonlinear forced vibrations of functionally graded multi-cracked beams
    Autorzy:
    Chajdi, Mohcine
    Adri, Ahmed
    El Bikri, Khalid
    Benamar, Rhali
    Powiązania:
    https://bibliotekanauki.pl/articles/1840885.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
    Tematy:
    nonlinear vibration
    multi-crack
    functionally graded beams
    forced vibrations
    drgania nieliniowe
    belki gradientowe
    rozkład naprężeń
    drgania wymuszone
    Opis:
    Geometrically non-linear vibrations of functionally graded Euler-Bernoulli beams with multi-cracks, subjected to a harmonic distributed force, are examined in this paper using a theoretical model based on Hamilton's principle and spectral analysis. The homogenisation procedure is performed, based on the neutral surface approach, and reduces the FG beams analysis to that of an equivalent homogeneous multi-cracked beam. The so-called multidimensional Duffing equation obtained and solved using a simplified method (second formulation) previously applied to various non-linear structural vibration problems. The curvature distributions associated to the multi-cracked beam forced deflection shapes are obtained for each value of the excitation level and frequency. The parametric study performed in the case of a beam and the detailed numerical results are given in hand to demonstrate the effectiveness of the proposed procedure, and in the other hand conducted to analyse many effects such as the beam material property, the presence of crack, the vibration amplitudes and the applied harmonic force on the non-linear dynamic behaviour of FG beams.
    Źródło:
    Diagnostyka; 2021, 22, 1; 101-112
    1641-6414
    2449-5220
    Pojawia się w:
    Diagnostyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A discrete model for nonlinear vibrations of a simply supported cracked beams resting on elastic foundations
    Autorzy:
    Khnaijar, A.
    Benamar, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/328710.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
    Tematy:
    nonlinear
    discrete
    beam
    Winkler foundation
    crack
    vibration
    drgania nieliniowe
    podłoże Winklera
    belka
    pęknięcie
    model
    Opis:
    The present paper introduces a discrete physical model to approach the problem of nonlinear vibrations of cracked beams resting on elastic foundations. It consists of a beam made of several small bars, evenly spaced, connected by spiral springs, presenting the beam bending stiffness. The crack is modeled by a spiral spring with a reduced stiffness and the Winkler soil stiffness is modeled using linear vertical springs. Concentrated masses, presenting the inertia of the beam, are located at the bar ends. The nonlinear effect, due to the axial forces in the bars resulting from the change in their length, is presented by longitudinal springs. This model has the advantage of simplifying parametric studies, because of its discrete nature, allowing any modification in the mass and the stiffness matrices, and in the nonlinearity tensor, to be made separately. After establishing the model, various practical applications are performed without the need of going through all the formulation again. Numerical linear and nonlinear results are given, corresponding to a cracked simply supported beam.
    Źródło:
    Diagnostyka; 2017, 18, 3; 39-46
    1641-6414
    2449-5220
    Pojawia się w:
    Diagnostyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Non-linear vibrations as a new diagnostic tool - crack detection example
    Autorzy:
    Kiciński, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/328752.pdf
    Data publikacji:
    2004
    Wydawca:
    Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
    Tematy:
    drgania nieliniowe
    dynamika maszyn
    maszyny wirnikowe
    pęknięcie
    non-linear vibration
    rotor dynamics
    crack detection
    Opis:
    It is widely acknowledged from literature that material or structural imperfections of the shaft crack type are capable, in some cases, of generating coupled non-linear forms of lateral-axial-torsional vibrations in the rotating machine. Such information, however, pertains to small or model objects of that type. In the paper presented are investigations into the influence of the shaft crack on the dynamic state of a large, multi-supported rotating machine. Determined have been the cases where the crack is capable of inducing pronounced forms of vibrations, which can serve as basis for more reliable and effective diagnostics, or the cases, where the mechanism of couplings deteriorates, despite the existence of cracks with significant depths. Determined has been the degree of sensitivity of non-linear and mutually coupled system vibrations on crack propagation and conducted had been the assessment of their applicability as a diagnostic determinant of a dynamic state in a large rotating machine.
    Znanym z literatury jest fakt, że imperfekcje materiałowe lub konstrukcyjne typu pęknięcie wału w niektórych przypadkach są w stanie wygenerować sprzężone drgania poprzeczno-wzdłużno-skrętne maszyny wirnikowej. Informacje te odnoszą się jednakże do małych lub modelowych obiektów tego typu. W pracy podjęte zostały badania wpływu pęknięcia wału na stan dynamiczny dużej, wielopodporowej maszyny wirnikowej. Określone zostały zarówno przypadki, dla których pęknięcie jest w stanie wywołać znaczące sprzężone formy drgań mogące być podstawą dla bardziej wiarygodnej i efektywnej diagnostyki, jak też i przypadki, dla których mechanizm sprzężeń zanika pomimo istnienia pęknięć o dużych głębokościach. Określony został stopień czułości nieliniowych i wzajemnie sprzężonych drgań układu na propagację pęknięcia oraz przeprowadzona została ocena ich użyteczności jako wyróżnika diagnostycznego stanu dynamicznego dużej maszyny wirnikowej.
    Źródło:
    Diagnostyka; 2004, 30, T. 1; 249-256
    1641-6414
    2449-5220
    Pojawia się w:
    Diagnostyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Linear and geometrically nonlinear free and forced vibrations of multi-cracked beams
    Autorzy:
    Chajdi, Mohcine
    Adri, Ahmed
    El Bikri, Khalid
    Benamar, Rhali
    Powiązania:
    https://bibliotekanauki.pl/articles/329328.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
    Tematy:
    nonlinear vibrations
    multi-crack
    Euler-Bernoulli beams
    free vibrations
    forced vibrations
    drgania nieliniowe
    drgania własne
    drgania wymuszone
    teoria Bernoulliego-Eulera
    Opis:
    The linear and geometrically nonlinear free and forced vibrations of Euler-Bernoulli beams with multicracks are investigated using the crack equivalent rotational spring model and the beam transfer matrix method. The Newton Raphson solution of the transcendental frequency equation corresponding to the linear case leads to the cracked beam linear frequencies and mode shapes. Considering the nonlinear case, the beam transverse displacement is expanded as a series of the linear modes calculated before. Using the discretised expressions for the total strain and kinetic energies and Hamilton’s principle, the nonlinear amplitude equation is obtained and solved using the so-called second formulation, developed previously for similar nonlinear structural dynamic problems, to obtain the multi-cracked beam backbone curves and the corresponding amplitude dependent nonlinear mode shapes. Considering the forced vibration case, the nonlinear frequency response functions obtained numerically near to the fundamental nonlinear mode using a single mode approach show the effects of the number of cracks, their locations and depths, and the level of the concentric harmonic force. The inverse problem is explored using the frequency contour plot method to identify crack parameters, such as the crack locations and depths. Satisfactory comparisons are made with previous analytical results.
    Źródło:
    Diagnostyka; 2019, 20, 1; 111-125
    1641-6414
    2449-5220
    Pojawia się w:
    Diagnostyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A discrete model for geometrically nonlinear free and forced vibrations of stepped and continuously segmented Euler-Bernoulli AFG beams (SAFGB) carrying point masses
    Autorzy:
    Moukhliss, Anass
    Rahmouni, Abdellatif
    Bouksour, Othman
    Benamar, Rhali
    Powiązania:
    https://bibliotekanauki.pl/articles/2146732.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
    Tematy:
    discrete model
    stepped beam
    free non-linear vibration
    forced nonlinear vibration
    AFG beam
    point mass
    model dyskretny
    belka o skokowo zmiennym przekroju
    drgania swobodne
    drgania wymuszone
    drgania nieliniowe
    Opis:
    A discrete model is applied to handle the geometrically nonlinear free and forced vibrations of beams consisting of several different segments whose mechanical characteristics vary in the length direction and contain multiple point masses located at different positions. The beam is presented by an N degree of freedom system (N-Dof). An approach based on Hamilton's principle and spectral analysis is applied, leading to a nonlinear algebraic system. A change of basis from the displacement basis to the modal basis has been performed. The mechanical behavior of the N-Dof system is described in terms of the mass tensor mij, the linear stiffness tensor kij, and the nonlinear stiffness tensor bijkl. The nonlinear vibration frequencies as functions of the amplitude of the associated vibrations in the free and forced cases are predicted using the single mode approach. Once the formulation is established, several applications are considered in this study. Different parameters control the frequency-amplitude dependence curve: the laws that describe the variation of the mechanical properties along the beam length, the number of added masses, the magnitude of excitation force, and so on. Comparisons are made to show the reliability and applicability of this model to non-uniform and non-homogeneous beams in free and forced cases.
    Źródło:
    Diagnostyka; 2022, 23, 4; art no 2022401
    1641-6414
    2449-5220
    Pojawia się w:
    Diagnostyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Linear and geometrically non-linear frequencies and mode shapes of beams carrying a point mass at various locations. An analytical approch and a parametric study
    Autorzy:
    Adri, A.
    Benamar, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/329670.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
    Tematy:
    non-linear vibration
    Hamilton’s principle
    Newton-Raphson method
    backbone curve
    second formulation
    drgania nieliniowe
    zasada Hamiltona
    metoda Newtona-Raphsona
    analiza modalna
    Opis:
    In the present paper, the frequencies and mode shapes of a clamped beam carrying a point mass, located at different positions, are investigated analytically and a parametric study is performed. The dynamic equation is written at two intervals of the beam span with the appropriate end and continuity conditions. After the necessary algebraic transformations, the generalised transcendental frequency equation is solved iteratively using the Newton Raphson method. Once the corresponding program is implemented, investigations are made of the changes in the beam frequencies and mode shapes for many values of the mass and mass location. Numerical results and plots are given for the clamped beam first and second frequencies and mode shapes corresponding to various added mass positions. The effect of the geometrical non-linearity is then examined using a single mode approach in order to obtain the corresponding backbone curves giving the amplitude dependent non-linear frequencies.
    Źródło:
    Diagnostyka; 2017, 18, 2; 13-21
    1641-6414
    2449-5220
    Pojawia się w:
    Diagnostyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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