Yazar "Alimoradzadeh M." seçeneğine göre listele

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    Nonlinear dynamic and stability of a beam resting on the nonlinear elastic foundation under thermal effect based on the finite strain theory
    (Techno-Press, 2021) Alimoradzadeh M.; Akbaş, Şeref Doǧuşcan; Esfrajani S.M.
    Nonlinear free vibration and thermal buckling of a beam resting on nonlinear are investigated in this study. In the nonlinear kinematic relations, the finite strain theory is used with Euler-Bernoulli and Hamilton's principle is employed to derive the nonlinear governing of motion. The Galerkin's method is applied to simplify the governing nonlinear partially differential equation to the nonlinear ordinary differential equation. In addition, He's variational method is employed to obtain an analytical expression for the nonlinear natural frequency and thermal buckling temperature. In this study, a comparison between the finite strain theory and the von Kármán Theory is presented and the results shows that the finite strain theory gives more accurate results than the von Kármán Theory for nonlinear natural frequency and thermal buckling temperature. In the numerical results, the effect of different parameters such as linear and nonlinear coefficients of the elastic foundation, boundary conditions and the amplitude of the oscillation on the thermal buckling temperature and the nonlinear natural frequency investigated.
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    Superharmonic and subharmonic resonances of atomic force microscope subjected to crack failure mode based on the modified couple stress theory
    (Springer Science and Business Media Deutschland GmbH, 2021) Alimoradzadeh M.; Akbaş, Şeref Doğuşcan
    The primary purpose of this paper is to investigate the nonlinear dynamic behavior of the atomic force microscopy (AFM) cantilever under the effect of concentrated point load at free end and the crack failure mode in the vicinity of the clamped-edge. The crack was modeled as rotational spring and the cracked AFM considered as a simply support-free micro-beam with a rotational spring in the simply support end. In the frame work of Euler–Bernoulli beam theory, Von-Karman type of geometric nonlinear equation and the modified couple stress theory the nonlinear equation of motion for the cracked AFM is derived by Hamilton’s principle and then discretized by using the Galerkin’s method. The method of multiple scale is employed to investigate, nonresonant hard excitation, superharmonic resonance and subharmonic resonance. Some numerical examples are presented to illustrate the effects of some parameters such as depth of the crack, length scale parameter, tip-mass, the magnitude and the location of the external excitation force on the stability of the response amplitude, and the unstable regions were identified.