Dynamic pull-in instability of electrostatically actuated beams incorporating Casimir and van der Waals forces

2010 ◽  
Vol 224 (9) ◽  
pp. 2037-2047 ◽  
Author(s):  
M Moghimi Zand ◽  
M T Ahmadian
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Van Der Waals ◽  
Time Discretization ◽  
Element Model ◽  
Intermolecular Forces ◽  
Governing Equations ◽  
Electrostatically Actuated ◽  
Clamped Beams ◽  
Fringing Fields

In this study, influences of intermolecular forces on the dynamic pull-in instability of electrostatically actuated beams are investigated. The effects of midplane stretching, electrostatic actuation, fringing fields, and intermolecular forces are considered. The boundary conditions of the beams are clamped—free and clamped—clamped. A finite-element model is developed to discretize the governing equations, and Newmark time discretization is then employed to solve the discretized equations. The static pull-in instability is investigated to validate the model. Finally, dynamic pull-in instability of cantilevers and double-clamped beams are studied considering the Casimir and van der Waals effects. The results indicate that by increasing the Casimir and van der Waals effects, the effect of inertia on pull-in values considerably increases.

Influence of Intermolecular Forces on Dynamic Pull-In Instability of Micro/Nano Bridges

2010 ◽  
Author(s):  
M. Moghimi Zand ◽  
M. T. Ahmadian
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Finite Element Model ◽  
Van Der Waals ◽  
Time Discretization ◽  
Element Model ◽  
Intermolecular Forces ◽  
Governing Equations ◽  
Electrostatically Actuated ◽  
Fringing Fields

In this study, influences of intermolecular forces on dynamic pull-in instability of electrostatically actuated beams are investigated. Effects of midplane stretching, electrostatic actuation, fringing fields and intermolecular forces are considered. The boundary conditions of the beams are clamped-free and clamped-clamped. A finite element model is developed to discretize the governing equations and Newmark time discretization is then employed to solve the discretized equations. The results indicate that by increasing the Casimir and van der Waals effects, the effect of inertia on pull-in values considerably increases.

Dynamic Pull-In Instability of Initially Curved Microbeams

2009 ◽  
Author(s):  
M. Moghimi Zand ◽  
M. T. Ahmadian ◽  
B. Rashidian
Keyword(s):  
Finite Element ◽  
Finite Difference ◽  
Finite Element Model ◽  
Electrostatic Force ◽  
Time Discretization ◽  
Element Model ◽  
Governing Equations ◽  
The Finite Element Model

In this study, dynamic pull-in instability and snap-through buckling of initially curved microbeams are investigated. The microbeams are actuated by suddenly applied electrostatic force. A finite element model is developed to discretize the governing equations and Newmark time discretization is employed to solve the discretized equations. The static pull-in behavior is investigated to validate the model. The results of the finite element model are compared with finite difference solutions and their convergence is examined. In addition, the influence of different parameters on dynamic pull-in instability and snap-through buckling is explored.

scholarly journals An extended finite-element model coupled with level set method for analysis of growth of corrosion pits in metallic structures

2014 ◽  
Vol 470 (2168) ◽  
pp. 20140001 ◽  
Author(s):  
A. S. Vagbharathi ◽  
S. Gopalakrishnan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Level Set Method ◽  
Level Set ◽  
Concentration Field ◽  
Element Model ◽  
Jump Discontinuity ◽  
Governing Equations ◽  
Extended Finite Element ◽  
Pitting Potential

Mass balance between metal and electrolytic solution, separated by a moving interface, in stable pit growth results in a set of governing equations which are solved for concentration field and interface position (pit boundary evolution). The interface experiences a jump discontinuity in metal concentration. The extended finite-element model (XFEM) handles this jump discontinuity by using discontinuous-derivative enrichment formulation, eliminating the requirement of using front conforming mesh and re-meshing after each time step as in the conventional finite-element method. However, prior interface location is required so as to solve the governing equations for concentration field for which a numerical technique, the level set method, is used for tracking the interface explicitly and updating it over time. The level set method is chosen as it is independent of shape and location of the interface. Thus, a combined XFEM and level set method is developed in this paper. Numerical analysis for pitting corrosion of stainless steel 304 is presented. The above proposed model is validated by comparing the numerical results with experimental results, exact solutions and some other approximate solutions. An empirical model for pitting potential is also derived based on the finite-element results. Studies show that pitting profile depends on factors such as ion concentration, solution pH and temperature to a large extent. Studying the individual and combined effects of these factors on pitting potential is worth knowing, as pitting potential directly influences corrosion rate.

Harmonic Wave Propagation and Testing of a Piezoelectric Curvilinear Arc Driver

2005 ◽  
Author(s):  
P. Smithmaitrie ◽  
H. S. Tzou
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Wave Propagation ◽  
Finite Element Model ◽  
Conceptual Model ◽  
Harmonic Wave ◽  
Element Model ◽  
Governing Equations ◽  
Circular Arc ◽  
The Finite Element Model

A piezoelectric curvilinear driver designed for an ultrasonic curvilinear motor is presented in this study. The design of piezoelectric curvilinear arc driver is proposed. The system governing equations, vibration behavior and wave propagation are investigated. Then, a conceptual model of piezoelectric circular arc driver is built and tested to demonstrate that the design of the curvilinear arc motor is feasible. Fabrication of the piezoelectric circular arc driver and implementation are respectively discussed, followed by results of the finite element model, and testing of the conceptual model. The demonstrations show that the curvilinear arc motor performs as expected. The experimental data is compared with the finite element results showing that the operating frequency of the conceptual motor compares well with the finite element result.

Finite Element Simulation of Tire-Rim Interface

1989 ◽  
Vol 17 (4) ◽  
pp. 305-325 ◽  
Author(s):  
N. T. Tseng ◽  
R. G. Pelle ◽  
J. P. Chang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Finite Element Simulation ◽  
Contact Pressure ◽  
Element Model ◽  
Experimental Measurements ◽  
Inflation Pressure ◽  
Interference Fit ◽  
Element Simulation ◽  
Rubber Composite

Abstract A finite element model was developed to simulate the tire-rim interface. Elastomers were modeled by nonlinear incompressible elements, whereas plies were simulated by cord-rubber composite elements. Gap elements were used to simulate the opening between tire and rim at zero inflation pressure. This opening closed when the inflation pressure was increased gradually. The predicted distribution of contact pressure at the tire-rim interface agreed very well with the available experimental measurements. Several variations of the tire-rim interference fit were analyzed.

Torsional Analysis of a Steel Cord-Rubber Tire Belt Structure

1996 ◽  
Vol 24 (4) ◽  
pp. 339-348 ◽  
Author(s):  
R. M. V. Pidaparti
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Composite Structures ◽  
Three Dimensional ◽  
Element Model ◽  
Torsional Stiffness ◽  
Element Analysis ◽  
Rubber Belt ◽  
Steel Cord ◽  
Torsional Analysis

Abstract A three-dimensional (3D) beam finite element model was developed to investigate the torsional stiffness of a twisted steel-reinforced cord-rubber belt structure. The present 3D beam element takes into account the coupled extension, bending, and twisting deformations characteristic of the complex behavior of cord-rubber composite structures. The extension-twisting coupling due to the twisted nature of the cords was also considered in the finite element model. The results of torsional stiffness obtained from the finite element analysis for twisted cords and the two-ply steel cord-rubber belt structure are compared to the experimental data and other alternate solutions available in the literature. The effects of cord orientation, anisotropy, and rubber core surrounding the twisted cords on the torsional stiffness properties are presented and discussed.

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