A Coupled Model Between Torsion and Bending in Nano/Micromirrors Under the Combined Effect of Van Der Waals Force and Capillary Force

2011 ◽  
Author(s):  
Hamid Moeenfard ◽  
Ali Darvishian ◽  
Mohammad Taghi Ahmadian
Keyword(s):  
Capillary Force ◽  
Coupling Effect ◽  
Van Der Waals ◽  
Coupled Model ◽  
Combined Effect ◽  
Static Behavior ◽  
Energy Principle ◽  
Total Potential ◽  
The Stability ◽  
Vdw Force

The coupling effect between torsion and bending in nano/micromirrors under the combined effect of capillary force and van der Waals (vdW) force is presented in this paper. At the first, the dimensionless equations governing the statical behavior of the nano/micromirror are obtained using the minimum total potential energy principle. Then the equations governing the pull-in state of the mirror are obtained using the implicit function theorem. The related results show that neglecting bending effect can lead to considerable overestimation in predicting the pull-in limits of the nano/micromirror under combined vdW and capillary forces. It is observed that vdW force reduces the pull-in angle and pull-in deflection of the supporting torsion beams of the mirror. The static behavior of the nano/micromirror under capillary and vdW loading is also studied and the results reveal that the static behavior of the nano/micromirror under capillary and vdW forces highly depends on the bending of the torsion beams. The results of this paper can be used for a safe and stable design and fabrication of mirrors using the wet etching process, where the gap between the mirror and the underneath substrate is sufficiently small and as a results both capillary and vdW forces have significant role in the stability of the system.

Closed Form Solutions for the Problem of Statical Behavior of Nano/Micromirrors Under the Effect of Capillary Force and Van Der Waals Force

2011 ◽  
Author(s):  
Ali Darvishian ◽  
Hamid Moeenfard ◽  
Hasan Zohoor ◽  
Mohammad Taghi Ahmadian
Keyword(s):  
Capillary Force ◽  
Rotation Angle ◽  
Van Der Waals ◽  
Van Der Waals Force ◽  
Combined Effect ◽  
Geometrical Parameters ◽  
Closed Form Solutions ◽  
The Stability ◽  
Vdw Force ◽  
Stability Limits

The current paper deals with the problem of static instability of Micro/Nano mirrors under the combined effect of capillary force and van der Waals force. First the governing equations of the statical behavior of Micro/Nano mirrors under the combined effect of capillary force and casimir force is obtained using the newtons first law of motion. The dependence of the critical tilting angle on the physical and geometrical parameters of the nano/micromirror and its supporting torsional beams is investigated. It is found that existence of vdW torque can considerably reduce the stability limits of the nano/micromirror. It is also found that rotation angle of the mirror due to capillary force highly depends on the vdW toque applied to the mirror. Finally analytical tool Homotopy Perturbation Mehtod (HPM) is utilized for prediction of the nano/micromirror behaviour under combined capillary and vdW force. It is observed that a sixth order perturbation approximation accurately predicts the rotation angle and stability limits of the mirror. Results of this paper can be used for successful fabrication of nano/micromirrors using wet etching process where capillary force plays a major role in the system.

INFLUENCE OF VAN DER WAALS FORCE ON STATIC BEHAVIOR OF NANO/MICROMIRRORS UNDER CAPILLARY FORCE

2012 ◽  
Vol 26 (07) ◽  
pp. 1250056 ◽  
Author(s):  
HAMID MOEENFARD ◽  
ALI DARVISHIAN ◽  
HASSAN ZOHOOR ◽  
MOHAMMAD TAGHI AHMADIAN
Keyword(s):  
Capillary Force ◽  
Rotation Angle ◽  
Van Der Waals ◽  
Geometrical Parameters ◽  
Static Behavior ◽  
Release Process ◽  
Dimensionless Equation ◽  
The Stability ◽  
Vdw Force ◽  
Stability Limits

In the current paper, the effect of van der Waals (vdW) force on the static behavior and pull-in characteristics of nano/micromirrors under capillary force is investigated. At first, the dimensionless equation governing the static behavior of nano/micromirrors is obtained. The dependence of the critical tilting angle on the physical and geometrical parameters of the nano/micromirror and its supporting torsional beams is investigated. It is found that the existence of vdW force can considerably reduce the stability limits of the nano/micromirror. It is also found that rotation angle of the mirror due to capillary force highly depends on the vdW force applied to the mirror. Finally, analytical tool Homotopy Perturbation Method (HPM) is utilized for prediction of the nano/micromirror behavior under combined capillary and vdW force. It is observed that a sixth order perturbation approximation accurately predicts the rotation angle and stability limits of the mirror. The results of this paper can be used for successful fabrication of nano/micromirrors using wet etching release process where capillary force plays a major role in the system.

scholarly journals Postbuckling Analysis Of A Rectangular Plate Loaded In Compression

2015 ◽  
Vol 15 (2) ◽  
Author(s):  
Jozef Havran ◽  
Martin Psotný
Keyword(s):  
Rectangular Plate ◽  
User Program ◽  
Nonlinear Fem ◽  
Buckling Mode ◽  
Energy Principle ◽  
Initial Imperfections ◽  
Potential Energy Principle ◽  
Total Potential ◽  
The Stability ◽  
Minimum Total Potential Energy

Abstract The stability analysis of a thin rectangular plate loaded in compression is presented. The nonlinear FEM equations are derived from the minimum total potential energy principle. The peculiarities of the effects of the initial imperfections are investigated using the user program. Special attention is paid to the influence of imperfections on the post-critical buckling mode. The FEM computer program using a 48 DOF element has been used for analysis. Full Newton-Raphson procedure has been applied.

Analytical Solutions for the Static Instability of Micro/Nano Mirrors Under the Combined Effect of Capillary Force and Casimir Force

2011 ◽  
Author(s):  
Hamid Moeenfard ◽  
Ali Darvishian ◽  
Mohammad Taghi Ahmadian
Keyword(s):  
Capillary Force ◽  
Casimir Force ◽  
Rotation Angle ◽  
Combined Effect ◽  
Geometrical Parameters ◽  
Casimir Forces ◽  
Tilting Angle ◽  
Static Instability ◽  
The Stability ◽  
Stability Limits

This paper deals with the problem of static instability of Micro/Nano mirrors under the combined effect of capillary force and Casimir force. At the First the governing equations of the statical behavior of Micro/Nano mirrors under the combined effect of capillary force and casimir force is obtained. The dependency of the critical tilting angle on the physical and geometrical parameters of the nano/micromirror and its supporting torsional beams is investigated. It is found that existence of casimir force can considerably reduce the stability limits of nano/micromirror. It is also found that rotation angle of the mirror due to capillary force highly depends on the casimir force applied to the mirror. Finally analytical tool Homotopy Perturbation Method (HPM) is utilized for prediction of the mirror’s behaviour under combined capillary and casimir forces. It is observed that a sixth order perturbation approximation accurately predicts the rotation angle and stability limits of the mirror. Results of this paper can be used for successful fabrication of nano/micromirrors using wet etching process where capillary force plays a major role in the system.

An hourglass-type electromagnetic isolator with negative resistance electromagnetic shunt circuit

2020 ◽  
Vol 64 (1-4) ◽  
pp. 549-556
Author(s):  
Yajun Luo ◽  
Linwei Ji ◽  
Yahong Zhang ◽  
Minglong Xu ◽  
Xinong Zhang
Keyword(s):  
Vibration Isolation ◽  
Electromechanical Coupling ◽  
Coupling Effect ◽  
Negative Resistance ◽  
Isolation System ◽  
Amplitude Vibration ◽  
Vibration Responses ◽  
The Stability ◽  
Isolation Performance ◽  
Shunt Circuit

The present work proposed an hourglass-type electromagnetic isolator with negative resistance (NR) shunt circuit to achieve the effective suppression of the micro-amplitude vibration response in various advanced instruments and equipment. By innovatively design of combining the displacement amplifier and the NR electromagnetic shunt circuit, the current new type of vibration isolator not only can effectively solve the problem of micro-amplitude vibration control, but also has significant electromechanical coupling effect, to obtain excellent vibration isolation performance. The design of the isolator and motion relationship is presented firstly. The electromechanical coupling dynamic model of the isolator is also given. Moreover, the optimal design of the NR electromagnetic shunt circuit and the stability analysis of the vibration isolation system are carried out. Finally, the simulation results about the transfer function and vibration responses demonstrated that the isolator has a significant isolation performance.

Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong
Keyword(s):  
Thin Films ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Thermal Equilibrium ◽  
Density Functional ◽  
Van Der Waals ◽  
Chemical Vapor ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

Isotope effects on the stability of the nitrogen—acetylene van der Waals dimer

1993 ◽  
Vol 171 (1-2) ◽  
pp. 89-95 ◽  
Author(s):  
Sean A.C. McDowell ◽  
A. David Buckingham
Keyword(s):  
Isotope Effects ◽  
Van Der Waals ◽  
The Stability ◽  
Van Der Waals Dimer

A First-Principles Method of Determining Van Der Waals Forces in a Dissipative Media

2012 ◽  
Author(s):  
Yi Zheng ◽  
Arvind Narayanaswamy
Keyword(s):  
Stress Tensor ◽  
First Principles ◽  
Van Der Waals ◽  
Maxwell Stress ◽  
Quantum Field ◽  
Maxwell Stress Tensor ◽  
Lifshitz Theory ◽  
Dissipative Media ◽  
Dissipative Material ◽  
Vdw Force

Lifshitz theory of van der Waals (vdW) force and energy is strictly valid when the location at which the stress tensor is calculated is in vacuum. Generalization of Lifshitz theory to the case when the stress tensor is to be calculated in a dissipative material, as opposed to vacuum, is a surprisingly difficult undertaking because there is no expression for the electromagnetic stress tensor in dissipative materials. Here, we derive the expression for vdW force in planar dissipative media by calculating the Maxwell stress tensor in a fictious layer of vacuum, that is eventually made to vanish, introduced in the structure, without employing the complicated quantum field theoretic method proposed by Dzyaloshinskii, Lifshitz, and Pitaevskii. Even though this work has proven to be a corroboration of Dzyaloshinskii et al., it has thrown new light on our understanding of vdW forces and suggests that it should be possible to achieve the similar result for objects with arbitrary shapes.

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