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Sritawat Kitipornchai - One of the best experts on this subject based on the ideXlab platform.

  • size effect on the free vibration of geometrically nonlinear functionally graded micro Beams under electrical actuation and temperature change
    Composite Structures, 2015
    Co-Authors: X.l. Jia, Sritawat Kitipornchai, Jie Yang, C B Feng
    Abstract:

    This paper investigated the size effect on the free vibration of functionally graded micro-Beams under the combined electrostatic force, temperature change and Casimir force based on Euler-Bernoulli Beam Theory and von Karman geometric nonlinearity. Taking into consideration the temperature-dependency of the effective material properties, material properties of the functionally graded materials (FGMs) are assumed to be graded in the thickness direction according to the Voigt model and exponential distribution model. The principle of minimum total potential energy is used to derive the nonlinear governing differential equation which is then solved using the differential quadrature method (DQM). A parametric study is conducted to show the significant combined effects of the size effect, material gradient, temperature change, geometric parameters and Casimir force.

  • thermal effect on the pull in instability of functionally graded micro Beams subjected to electrical actuation
    Composite Structures, 2014
    Co-Authors: X.l. Jia, Jie Yang, S M Zhang, Sritawat Kitipornchai
    Abstract:

    The thermal effect on the pull-in instability of functionally graded micro-Beams under the combined electrostatic force, temperature change and Casimir force is studied based on Euler-Bernoulli Beam Theory and von Karman geometric nonlinearity. Take into consideration the temperature-dependency of the effective material properties, the Voigt model and exponential distribution model is used to simulate the material properties of the functionally graded materials (FGMs). Principle of virtual work is used to derive the nonlinear governing differential equation which is then solved using the differential quadrature method (DQM). A parametric study is conducted to show the significant effects of material composition, temperature change, geometric nonlinearity and Casimir force.

  • an analytical study on the nonlinear vibration of functionally graded Beams
    Meccanica, 2010
    Co-Authors: Jie Yang, Sritawat Kitipornchai
    Abstract:

    Nonlinear vibration of Beams made of functionally graded materials (FGMs) is studied in this paper based on Euler-Bernoulli Beam Theory and von Karman geometric nonlinearity. It is assumed that material properties follow either exponential or power law distributions through thickness direction. Galerkin procedure is used to obtain a second order nonlinear ordinary equation with quadratic and cubic nonlinear terms. The direct numerical integration method and Runge-Kutta method are employed to find the nonlinear vibration response of FGM Beams with different end supports. The effects of material property distribution and end supports on the nonlinear dynamic behavior of FGM Beams are discussed. It is found that unlike homogeneous Beams, FGM Beams show different vibration behavior at positive and negative amplitudes due to the presence of quadratic nonlinear term arising from bending-stretching coupling effect.

Mesut Simsek - One of the best experts on this subject based on the ideXlab platform.

  • large amplitude free vibration of nanoBeams with various boundary conditions based on the nonlocal elasticity Theory
    Composites Part B-engineering, 2014
    Co-Authors: Mesut Simsek
    Abstract:

    Abstract In this paper, a non-classical Beam model based on the Eringen’s nonlocal elasticity Theory is proposed for nonlinear vibration of nanoBeams with axially immovable ends. This non-classical (nonlocal) Beam model incorporates the length scale parameter (nonlocal parameter) which can capture the small scale effect. The Hamilton’s principal is employed to derive the governing equations and the related boundary conditions together with Euler–Bernoulli Beam Theory and the von-Karman’s nonlinear strain–displacement relationships. An approximate analytical solution is obtained for the nonlinear frequency of the nanoBeam by utilizing the Galerkin method and He’s variational method. In the numerical results, the ratio of nonlinear frequency to linear frequency is presented for three different boundary conditions. The effect of nonlocal parameter on the nonlinear frequency ratio is examined. Also, some illustrative examples are also presented to verify the present formulation and solutions. Good agreement is observed. These results can be used as benchmark for future studies.

  • analytical solutions for bending and buckling of functionally graded nanoBeams based on the nonlocal timoshenko Beam Theory
    Composite Structures, 2013
    Co-Authors: Mesut Simsek, H H Yurtcu
    Abstract:

    In this paper, static bending and buckling of a functionally graded (FG) nanoBeam are examined based on the nonlocal Timoshenko and Euler–Bernoulli Beam Theory. This non-classical (nonlocal) nanoBeam model incorporates the length scale parameter (nonlocal parameter) which can capture the small scale effect. The material properties of the FG nanoBeam are assumed to vary in the thickness direction. The governing equations and the related boundary conditions are derived using the principal of the minimum total potential energy. The Navier-type solution is developed for simply-supported boundary conditions, and exact formulas are proposed for the deflections and the buckling load. The effects of nonlocal parameter, aspect ratio, various material compositions on the static and stability responses of the FG nanoBeam are discussed. Some illustrative examples are also presented to verify the present formulation and solutions. Good agreement is observed. The results show that the new nonlocal Beam model produces larger deflection and smaller buckling load than the classical (local) Beam model.

  • vibration analysis of a single walled carbon nanotube under action of a moving harmonic load based on nonlocal elasticity Theory
    Physica E-low-dimensional Systems & Nanostructures, 2010
    Co-Authors: Mesut Simsek
    Abstract:

    Abstract In the present study, forced vibration of a simply supported single-walled carbon nanotube (SWCNT) subjected to a moving harmonic load is investigated by using nonlocal Euler–Bernoulli Beam Theory. The time-domain responses are obtained by using both the modal analysis method and the direct integration method. The effects of nonlocal parameter, aspect ratio, velocity and the excitation frequency of the moving load on the dynamic responses of SWCNT is discussed. For comparison purposes, free vibration frequencies and static deflections of the SWCNT subjected to a point load at the midpoint are obtained and compared with previously published studies. Good agreement is observed. The results show that dynamic deflections of the SWCNT increase with increase in the nonlocal parameter, which means that dynamic deflections based on the local Beam Theory are underestimated, and the effect of nonlocal parameter is dependent on the aspect ratio. Furthermore, load velocity and the excitation frequency play an important role on the dynamic behavior of the SWCNT.

  • free and forced vibration of a functionally graded Beam subjected to a concentrated moving harmonic load
    Composite Structures, 2009
    Co-Authors: Mesut Simsek, Turgut Kocaturk
    Abstract:

    Abstract In this paper, free vibration characteristics and the dynamic behavior of a functionally graded simply-supported Beam under a concentrated moving harmonic load are investigated. The system of equations of motion is derived by using Lagrange’s equations under the assumptions of the Euler–Bernoulli Beam Theory. Trial functions denoting the transverse and the axial deflections of the Beam are expressed in polynomial forms. The constraint conditions of supports are taken into account by using Lagrange multipliers. It is assumed that material properties of the Beam vary continuously in the thickness direction according to the exponential law and the power-law form. In this study, the effects of the different material distribution, velocity of the moving harmonic load, the excitation frequency on the dynamic responses of the Beam are discussed. Numerical results show that the above-mentioned effects play very important role on the dynamic deflections of the Beam.

Ömer Civalek - One of the best experts on this subject based on the ideXlab platform.

  • a new nonlocal fem via hermitian cubic shape functions for thermal vibration of nano Beams surrounded by an elastic matrix
    Composite Structures, 2017
    Co-Authors: Cigdem Demir, Ömer Civalek
    Abstract:

    Abstract In this study, vibration formulation is presented for nano-scaled Beam embedded in an elastic matrix under the effect of thermal environments. The effect of length scale is investigated using Eringen’s nonlocal elasticity Theory. The governing equations are obtained by using Hamilton’s principle and variational approach. Finite element formulation has been achieved based on the nonlocal Euler–Bernoulli Beam Theory for nano-scaled Beam. Galerkin method of weighted residuals is considered for development the global stiffness and mass matrices via Hermitian cubic shape functions. The residue is minimized over the elements, after that the shape function is applied to the obtained equation. The influences of the Pasternak foundation parameter, small scale parameter, mechanical properties of material and thermal effect on vibrational frequency are investigated. As a special case, some results have also been given for silicon carbide nanowires.

  • Comparison of small scale effect theories for buckling analysis of nanoBeams
    Akdeniz University, 2017
    Co-Authors: Kadir Mercan, Ömer Civalek
    Abstract:

    Theories which consider small scale effect have a great importance on analysis in micro and nano scale. In present paper, three kind of nanotubes (Carbon Nanotube (CNT), Boron Nitride Nanotube (BNNT), and Silicon Carbide Nanotube (SiCNT)) are analyzed in case of buckling on two parameters elastic foundation. Three different small scale theories (Nonlocal Elasticity Theory (NET), Surface Elasticity Theory (SET), and Nonlocal Surface Elasticity Theory (NET&SET)) are applied to calculate the buckling loads. Also Classical Euler-Bernoulli Beam Theory (CT) is used to see the effect of small scale effective theories. Comparative results are given for simply supported nanotubes in figures

  • dsc method for buckling analysis of boron nitride nanotube bnnt surrounded by an elastic matrix
    Composite Structures, 2016
    Co-Authors: Kadir Mercan, Ömer Civalek
    Abstract:

    Abstract A simple mechanical model for buckling behavior of boron nitride nanotube (BNNT) surrounded by an elastic matrix is presented. A nonlocal-continuum model is proposed for BNNT using the Euler–Bernoulli Beam Theory on an elastic matrix. The elastic matrix surrounded of the BNNT is modeled via linear spring model using the Winkler and Pasternak elastic foundation models. The equation is obtained by variational approach for buckling and has been solved by two different approaches. Separation of variables and method of discrete singular convolution are used for computations. The influences of some geometric parameters of BNNT on buckling behavior are investigated in detail. The effect of mode numbers and nonlocal parameter on buckling behavior of BNNT has also been investigated. Finally, some parametric results are presented for BNNT buckling. It is noticed that the present DSC approach can predict accurately the buckling loads for nano-scaled structures.

  • bending analysis of microtubules using nonlocal euler bernoulli Beam Theory
    Applied Mathematical Modelling, 2011
    Co-Authors: Ömer Civalek, Cigdem Demir
    Abstract:

    In this paper, elastic Beam model using nonlocal elasticity Theory is developed for the bending analysis of microtubules (MTs) based on the Euler–Bernoulli Beam Theory. The size effect is taken into consideration using the Eringen’s non-local elasticity Theory. The derivation of governing equation of bending from shear and moment resultants of the Beam and stress–strain relationship of the one-dimensional nonlocal elasticity model is presented. The model is then applied on the studies of static analysis of microtubules using the method of differential quadrature (DQ). After the developed DQ method is numerically validated, detailed numerical analyses about the effects of boundary conditions and load types are conducted and the influence of nonlocal parameter on the static response of MTs is discussed. It is hoped that the results in the manuscript may present a benchmark in the study of bending in microtubules.

  • free vibration analysis of microtubules as cytoskeleton components nonlocal euler bernoulli Beam modeling
    Scientia Iranica, 2010
    Co-Authors: Ömer Civalek, B Akgoz
    Abstract:

    Free vibration analysis of microtubules (MTs) is presented based on the Euler-Bernoulli Beam Theory. The size eect is taken into consideration using the Eringen's non-local elasticity Theory. The governing dierential equations for MT vibrations are being solved using the Dierential Quadrature (DQ) method. Numerical results are presented to show the eect of nonlocal behavior on the frequencies of MTs. It is hoped that the results in the manuscript may present a benchmark in the study of vibration for microtubules.

M M Aghdam - One of the best experts on this subject based on the ideXlab platform.

  • a semi analytical approach for large amplitude free vibration and buckling of nonlocal fg Beams resting on elastic foundation
    Composite Structures, 2015
    Co-Authors: H Niknam, M M Aghdam
    Abstract:

    Abstract In this paper, an attempt is made to obtain a closed form solution for both natural frequency and buckling load of nonlocal FG Beams resting on nonlinear elastic foundation. Implementing Eringen’s nonlocal elasticity Theory, the effect of nonlocality is introduced into the Euler–Bernoulli Beam Theory to obtain the nonlinear governing partial differential equation. Application of the Galerkin technique to the governing equation leads to a nonlinear ODE in the time-domain. Finally, natural frequency of the FG nano Beam is obtained using He’s variational method. It is shown that considering the nonlocal effects decreases the buckling load as well as natural frequency. Results also reveal that effects of nonlocal parameters on fully clamped Beams are more than other types of boundary conditions. Moreover, it is shown that the effect of nonlocality decreases by increasing length of the Beam.

  • effect of nonlinear elastic foundation on large amplitude free and forced vibration of functionally graded Beam
    Composite Structures, 2014
    Co-Authors: A S Kanani, H Niknam, Abdolreza Ohadi, M M Aghdam
    Abstract:

    Abstract Large amplitude free and forced vibration of FG Beam resting on nonlinear elastic foundation containing shearing layer and cubic nonlinearity are investigated. The material properties are assumed to vary continuously according to a simple power law. The theoretical formulations and governing partial deferential equation of motion are derived based on Euler–Bernoulli Beam Theory and von Karman geometric nonlinearity. Adopting appropriate trial functions for various boundary conditions and employing Galerkin technique and assuming a uniformly distributed harmonic load, single nonlinear ordinary differential equation with quadratic and cubic nonlinearities is obtained. Variational Iteration Method (VIM) is used to derive closed form approximate solutions for both free and forced vibration. Comparison of the acquired results with those of existence literature revealed good agreement with a desired accuracy. The frequency response curves are presented for different coefficients of elastic foundation together with various boundary conditions and the effects of nonlinearities are discussed in detail.

Jie Yang - One of the best experts on this subject based on the ideXlab platform.

  • size effect on the free vibration of geometrically nonlinear functionally graded micro Beams under electrical actuation and temperature change
    Composite Structures, 2015
    Co-Authors: X.l. Jia, Sritawat Kitipornchai, Jie Yang, C B Feng
    Abstract:

    This paper investigated the size effect on the free vibration of functionally graded micro-Beams under the combined electrostatic force, temperature change and Casimir force based on Euler-Bernoulli Beam Theory and von Karman geometric nonlinearity. Taking into consideration the temperature-dependency of the effective material properties, material properties of the functionally graded materials (FGMs) are assumed to be graded in the thickness direction according to the Voigt model and exponential distribution model. The principle of minimum total potential energy is used to derive the nonlinear governing differential equation which is then solved using the differential quadrature method (DQM). A parametric study is conducted to show the significant combined effects of the size effect, material gradient, temperature change, geometric parameters and Casimir force.

  • thermal effect on the pull in instability of functionally graded micro Beams subjected to electrical actuation
    Composite Structures, 2014
    Co-Authors: X.l. Jia, Jie Yang, S M Zhang, Sritawat Kitipornchai
    Abstract:

    The thermal effect on the pull-in instability of functionally graded micro-Beams under the combined electrostatic force, temperature change and Casimir force is studied based on Euler-Bernoulli Beam Theory and von Karman geometric nonlinearity. Take into consideration the temperature-dependency of the effective material properties, the Voigt model and exponential distribution model is used to simulate the material properties of the functionally graded materials (FGMs). Principle of virtual work is used to derive the nonlinear governing differential equation which is then solved using the differential quadrature method (DQM). A parametric study is conducted to show the significant effects of material composition, temperature change, geometric nonlinearity and Casimir force.

  • an analytical study on the nonlinear vibration of functionally graded Beams
    Meccanica, 2010
    Co-Authors: Jie Yang, Sritawat Kitipornchai
    Abstract:

    Nonlinear vibration of Beams made of functionally graded materials (FGMs) is studied in this paper based on Euler-Bernoulli Beam Theory and von Karman geometric nonlinearity. It is assumed that material properties follow either exponential or power law distributions through thickness direction. Galerkin procedure is used to obtain a second order nonlinear ordinary equation with quadratic and cubic nonlinear terms. The direct numerical integration method and Runge-Kutta method are employed to find the nonlinear vibration response of FGM Beams with different end supports. The effects of material property distribution and end supports on the nonlinear dynamic behavior of FGM Beams are discussed. It is found that unlike homogeneous Beams, FGM Beams show different vibration behavior at positive and negative amplitudes due to the presence of quadratic nonlinear term arising from bending-stretching coupling effect.