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    Wyświetlanie 1-9 z 9
    Tytuł:
    Numerical simulation of single- and multi-step shear stress relaxations of isotropic magnetorheological elastomer using fractional derivative viscoelastic models
    Autorzy:
    Nam, T. H.
    Petríková, I.
    Marvalová, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/38695689.pdf
    Data publikacji:
    2022
    Wydawca:
    Instytut Podstawowych Problemów Techniki PAN
    Tematy:
    magnetorheological elastomer
    stress relaxation
    fractional viscoelastic
    model
    magnetic field
    Opis:
    The paper presents numerical simulations of single- and multi-step shear stress relaxations of isotropic magnetorheological elastomer (MRE) using fractional derivative Maxwell and Kelvin–Voigt viscoelastic models. The isotropic MRE has been fabricated by filling micro-sized carbonyl iron particles in silicone rubber. Fractional derivative Maxwell and Kelvin–Voigt viscoelastic models were used to fit the experimental data of the isotropic MRE measured by single- and multi-step relaxation tests at different constant strains and external magnetic fields. The fractional Maxwell viscoelastic model showed a relatively large difference between the measured and calculated results. The fractional Kelvin–Voigt model was fitted well with the experimental data of the isotropic MRE at various constant strain levels under different magnetic fields in both single- and multi-step shear stress relaxations. The calculated shear stress with the long-term prediction is in excellent agreement with the measured one. Therefore, the fractional derivative Kelvin–Voigt viscoelastic model is applicable to predict the long-term stress relaxation of the isotropic MRE.
    Źródło:
    Archives of Mechanics; 2022, 74, 4; 251-266
    0373-2029
    Pojawia się w:
    Archives of Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Axial vibration of bars using fractional viscoelastic material models
    Autorzy:
    Łabędzki, P.
    Pawlikowski, R.
    Radowicz, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/127834.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    fractional calculus
    fractional viscoelastic material models
    vibration of continuous system
    pochodna ułamkowa
    modele materiałów lepkosprężystych
    drgania układów ciągłych
    Opis:
    This paper presents dynamic analysis of a bar with one end fixed and other free, loaded with force at its free end. The viscoelastic material of the bar is described by fractional models (Scot-Blair, Voigt, Maxwell and Zener models). Rayleigh-Ritz and Laplace transform methods were applied to obtain closed-form solution of the considered problem.
    Źródło:
    Vibrations in Physical Systems; 2018, 29; 1-8
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Property identification of viscoelastic solid materials in nomograms using optimization techniques
    Autorzy:
    de Sousa, T. L.
    Kanke, F.
    Pereira, J. T.
    Bavastri, C. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/280283.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    identification
    optimization
    viscoelastic materials
    Zener fractional model
    Wiechert model
    Opis:
    Viscoelastic materials have been widely used as devices for vibration control in general. Frequently, dynamic properties of those materials are provided by manufacturers only in a graph form in the frequency domain. This is a recurring problem in industry and academia. Thereby, the goal of this work is to contribute to this important issue which is to obtain the properties of viscoelastic materials from nomograms supplied by the manufacturer. The methodology is based on the digitalization of the nomogram of the material and on the subsequent reading of a set of points from two curves in different temperatures. An optimization problem with simple restrictions is built having characteristic constants of the constitutive models as design variables. The problem is solved by applying a hybrid optimization technique. The results obtained are presented, and prove to be very promising.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2017, 55, 4; 1285-1297
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modal analysis of frame structures with semi-rigid joints and viscoelastic connections modeled by fractional derivatives
    Autorzy:
    Pawlak, Z. M.
    Łasecka-Plura, M.
    Zak-Sawiak, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/38697100.pdf
    Data publikacji:
    2023
    Wydawca:
    Instytut Podstawowych Problemów Techniki PAN
    Tematy:
    viscoelastic connection
    rotational damping
    rheological fractional model
    dynamic characteristics of structure
    modified finite element
    Opis:
    The paper presents two methods of solving the problem of the dynamics of a frame structure with viscoelastic bonds in nodes. In the first approach, known from the literature, two-node beam elements with three degrees of freedom in each node were used. Exact shape functions were adopted to obtain a stiffness matrix, a consistent mass matrix and a damping matrix for the beam element. These matrices were then modified by introducing rotational viscoelastic constraints at the boundary nodes. In the second approach, a new method of modelling viscoelastic bonds in frame structures was proposed. It consists in removing rigid bonds between elements along selected degrees of freedom and replacing them with a new, additional element with viscoelastic properties. This approach allows the use of any rheological model to describe viscoelastic bonds (i.e. an additional element) without the need to create a new modified finite element. In this work, an advanced rheological model, i.e. the fractional Kelvin model, was used to describe rotational viscoelastic bonds. The use of fractional derivatives to describe the damping properties reduces the number of parameters needed in the model, but leads to a non-linear eigenproblem. In order to solve the eigenvalue problem, the continuation method was used, and the dynamic characteristics of the structure were determined on the basis of the calculated eigenvalues. Selected structures with viscoelastic nodes were analyzed and the obtained results confirm the effectiveness of the proposed approach.
    Źródło:
    Archives of Mechanics; 2023, 75, 3; 337-363
    0373-2029
    Pojawia się w:
    Archives of Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nonlinear dynamic analysis of viscoelastic membranes described with fractional differential models
    Analiza nieliniowej dynamiki lepko-sprężystych powłok opisanych modelem o pochodnej ułamkowej
    Autorzy:
    Katsikadelis, J. T.
    Powiązania:
    https://bibliotekanauki.pl/articles/280344.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    viscoelastic membranes
    nonlinear vibrations
    nonlinear fractional differential equations
    analog equation method
    boundary elements
    Opis:
    The dynamic response of an initially flat viscoelastic membrane is investigated. The viscoelastic model is described with fractional order derivatives. The membrane is subjected to surface transverse and inplane dynamic loads. The governing equations are three coupled second order nonlinear partial FDEs (fractional differential equations) of hyperbolic type in terms of the displacement components. These equations are solved using the BEM for fractional partial differential equations developed recently by Katsikadelis. Without excluding other viscoelastic models, the herein employed material is the Kelvin-Voigt model with a fractional order derivative. Numerical examples are presented which not only demonstrate the efficiency of the solution procedure, but also give a better insight into this complicated but very interesting response of structural viscoelastic membranes. It is worth noting that in case of resonance, phenomena similar to those of the Duffing equation are observed.
    W pracy przedstawiono analizę dynamiki płaskiej powłoki lepko-sprężystej po wstępnym ugięciu. Reologiczny model materiału powłoki opisano równaniem o pochodnych ułamkowych. Powłokę poddano płaskiemu, poprzecznemu obciążeniu zewnętrznemu. Zagadnienie dynamiki ujęto układem trzech sprzężonych nieliniowych równań różniczkowych typu hiperbolicznego o pochodnych ułamkowych. Równania rozwiązano metodą elementów brzegowych (BEM) sformułowaną przez autora właśnie dla układów opisanych pochodnymi ułamkowymi. W prezentowanej pracy założono, że powłoka wykonana jest z lepko-sprężystego materiału Kelvina-Voigta o pochodnej ułamkowej, choć samo sformułowanie BEM nie wyklucza możliwości analizy innych modeli reologicznych. Przedstawiono kilka przykładów symulacji numerycznych pokazujących efektywność zastosowanej metody rozwiązywania oraz dających lepszy obraz interesującej, lecz skomplikowanej dynamiki lepko-sprężystych powłok. Warto również podkreślić, że w warunkach rezonansowych odnotowano zjawiska podobne do obserwowanych w układzie Duffinga.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2012, 50, 3; 743-753
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A quadrature-free Legendre polynomial approach for the fast modelling guided circumferential wave in anisotropic fractional order viscoelastic hollow cylinders
    Autorzy:
    Zhang, X.
    Liang, S.
    Shao, S.
    Yu, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/38615994.pdf
    Data publikacji:
    2021
    Wydawca:
    Instytut Podstawowych Problemów Techniki PAN
    Tematy:
    guided wave
    fractional order derivative
    anisotropic viscoelastic hollow cylinder
    quadrature-free Legendre polynomial approach
    dispersion
    attenuation
    Opis:
    Compared to the traditional integer order viscoelastic model, a fractional order derivative viscoelastic model is shown to be advantageous. The characteristics of guided circumferential waves in an anisotropic fractional order Kelvin–Voigt viscoelastic hollow cylinder are investigated by a quadrature-free Legendre polynomial approach combining the Weyl definition of fractional order derivatives. The presented approach can obtain dispersion solutions in a stable manner from an eigenvalue/eigenvector problem for the calculation of wavenumbers and displacement profiles of viscoelastic guided wave, which avoids a lot of numerical integration calculation in a traditional polynomial method and greatly improves the computational efficiency. Comparisons with the related studies are conducted to validate the correctness of the presented approach. The full three dimensional spectrum of an anisotropic fractional Kelvin–Voigt hollow cylinder is plotted. The influence of fractional order and material parameters on the phase velocity dispersion and attenuation curves of guided circumferential wave is discussed in detail. Moreover, the difference of the phase velocity dispersion and attenuation characteristics between the Kelvin–Voigt and hysteretic viscoelastic models is also illustrated. The presented approach along with the observed wave features should be particularly useful in non-destructive evaluations using waves in viscoelastic waveguides.
    Źródło:
    Archives of Mechanics; 2021, 73, 2; 121-152
    0373-2029
    Pojawia się w:
    Archives of Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A comparative study of the sensitivity analysis for systems with viscoelastic elements
    Autorzy:
    Łasecka-Plura, Magdalena
    Powiązania:
    https://bibliotekanauki.pl/articles/27309874.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    sensitivity analysis
    viscoelastic damping elements
    dynamic characteristics
    fractional
    derivatives
    analiza wrażliwości
    lepkosprężyste elementy tłumiące
    charakterystyka dynamiczna
    Opis:
    This paper discusses the different methods used for calculating first- and second-order sensitivity: the direct differentiation method, the adjoint variables method, and the hybrid method. The solutions obtained allow determining the sensitivity of dynamic characteristics such as eigenvalues and eigenvectors, natural frequencies, and nondimensional damping ratios. The methods were applied for analyzing systems with viscoelastic damping elements, whose behavior can be described by classical and fractional rheological models. However, the derived formulas are general and can also be applied to systems with damping elements described by other models. Their advantage is a compact and easy to code form. The paper also presents a comparison of the computational costs of the discussed methods. The correctness of all the proposed methods has been illustrated with numerical examples.
    Źródło:
    Archive of Mechanical Engineering; 2023, LXX, 1; 5--25
    0004-0738
    Pojawia się w:
    Archive of Mechanical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dynamic characteristics of the structure with viscoelastic dampers combined with inerters and subjected to temperature changes
    Autorzy:
    Pawlak, Zdzisław M.
    Lewandowski, Roman
    Powiązania:
    https://bibliotekanauki.pl/articles/2146557.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    viscoelastic damper
    inerter
    temperature
    fractional derivative
    nonlinear eigenvalue problem
    tłumik lepkosprężysty
    temperatura
    pochodna ułamkowa
    nieliniowe zagadnienie własne
    Opis:
    The purpose of the work is dynamic analysis of passive dampers used in structural systems to reduce excessive vibrations caused by wind or earthquakes. Special systems are considered that contain inerter, i.e. device using rotational inertia, in combination with a viscoelastic damper. The so-called fractional models of viscoelastic dampers describe their dynamic behavior in a wide frequency range using a small number of model parameters. To describe material behavior over a wider frequency range, the time-temperature superposition principle is used. The shifting factor is calculated from the well-known William-Landel-Ferry formula. This allows for determination of damper parameters at any temperature based on the parameters obtained at the reference temperature. Laplace transformation of the derived equations of motion leads to the non-linear eigenproblem, which could be solved using the continuation method. The influence of temperature on the dynamic characteristics of the system is examined.
    Źródło:
    Vibrations in Physical Systems; 2020, 31, 2; art. no. 2020222
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Approximate method for determination of dynamic characteristics of structures with viscoelastic dampers
    Autorzy:
    Lewandowski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/127718.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    structures
    viscoelastic damper
    generalized fractional model
    dynamic characteristics
    struktury
    tłumik lepkosprężysty
    uogólniony model ułamkowy
    charakterystyka dynamiczna
    Opis:
    An approximate method for determination of dynamic characteristics of structures with viscoelastic dampers is proposed in this paper. A fractional derivative is used to describe the dynamic behaviour of viscoelastic dampers. The method is based on a continuous dependency of the sensitivity of eigenvalue on a certain artificially introduced parameter which scaled up the influence of the damping term in the eigenvalue problem. Some results of a representative calculation are also presented and briefly discussed.
    Źródło:
    Vibrations in Physical Systems; 2016, 27; 219-226
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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