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RISS 인기검색어
- 검색키워드
- 저자 : Hamid Moeenfard (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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A homotopy perturbation analysis of nonlinear free vibration of Timoshenko microbeams
Hamid Moeenfard,Mahdi Mojahedi,Mohammad Taghi Ahmadian 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.3
This paper uses He’s Homotopy Perturbation Method (HPM) to analyze the nonlinear free vibrational behavior of clamped-clamped and clamped-free microbeams considering the effects of rotary inertia and shear deformation. Galerkin’s projection method is used to reduce the governing nonlinear partial differential equation. to a nonlinear ordinary differential equation. HPM is used to find analytic expressions for nonlinear natural frequencies of the pre-stretched microbeam. A parametric study investigated the effects of design parameters such as applied axial loads and slenderness ratio. The effect of rotary inertia and shear deformation on the nonlinear natural frequency was investigated. For verification, a numerical approach was implemented to solve the nonlinear equation. of vibration. A comparison between analytical and numerical results shows that HPM can predict system nonlinear vibrational behavior significantly more accurately than previously used methods in the literature.
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Hamid Moeenfard,Mohammad Taghi Ahmadian 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5
The objective of this work is to create an analytical framework to study the static pull-in and also equilibrium behavior in electrostatically actuated torsional micromirrors. First the equation governing the static behavior of electrostatic torsion micromirrors is derived and normalized. Perturbation method, the method of straight forward expansion is utilized to find the pull-in angle of the mirror. Comparison of the presented results with numerical ones available in the literature shows that the proposed second order perturbation expansion gives very precise approximations for the pull-in angle of the mirror. Then straightforward perturbation expansion method is used again to analytically simulate the voltage dependent behavior in electrostatic torsion micromirrors. The results are compared with numerical and experimental findings and excellent agreement is observed.
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Static behavior of nano/micromirrors under the effect of Casimir force, an analytical approach
Hamid Moeenfard,Ali Darvishian,Mohammad Taghi Ahmaidan 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.2
In this paper, static behavior of nano/micromirrors under Casimir force is studied. At the first, the equilibrium equation governing the statical behavior of nano/micromirrors is obtained. Then energy method is employed to investigate statical stability of nano/micromirrors equilibrium points and a useful equation is suggested for successful and stable design of nano/micromirrors under Casimir force. Then,equilibrium angle of nano/micromirrors is calculated both numerically and analytically using the homotopy perturbation method (HPM). It is observed that with increasing the instability number defined in the paper, the rotation angle of the mirror is increased and suddenly,pull-in occurs. Since analytical results well follow the numerical ones, the presented analytical method in this paper can be used as a fast,precise and stable design tool in nano/micromirrors under Casimir force.
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