Subharmonic Excitation for Electrically Actuated Microbeams

Author(s):  
Ali H. Nayfeh ◽  
Mohammad I. Younis

We present analysis of the global dynamics of electrically actuated microbeams under subharmonic excitation. The microbeams are excited by a DC electrostatic force and an AC harmonic force with a frequency tuned near twice their fundamental natural frequencies. We show that the dynamic pull-in instability can occur in this case for an electric load much lower than that predicted with static analysis and the same order-of-magnitude as that predicted in the case of primary-resonance excitation. We show that, once the subharmonic resonance is activated, all frequency-response curves reach pull-in, regardless of the magnitude of the AC forcing. Our results show a limited influence of the quality factor on the frequency response. This result and the fact that the frequency-response curves have very steep passband-to-stopband transitions make the combination of a DC voltage and a subhormonic of order one-half a promising candidate for designing improved high-sensitive RF MEMS filters.

Author(s):  
Ali H. Nayfeh ◽  
Mohammad I. Younis ◽  
Eihab M. Abdel-Rahman

We present a dynamic analysis and simulation of electrically actuated microelectromechanical systems (MEMS) resonators under primary-resonance excitation. We use a shooting technique, perturbation techniques, and long-time integration of the equation of motion to investigate the global dynamics of the resonators. We study the dynamic pull-in instability and show various scenarios and mechanisms for its occurrence. Our results show that dynamic pull-in can occur through a saddle-node bifurcation, a period-doubling bifurcation, or homoclinic tangling, depending on factors such as the initial conditions of the device and the level of the electrostatic force.


2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jihai Yuan ◽  
Xiangmin Zhang ◽  
Changping Chen

Since microplates are extensively used in MEMS devices such as microbumps, micromirrors, and microphones, this work aims to study nonlinear vibration of an electrically actuated microplate whose four edges are clamped. Based on the modified couple stress theory (MCST) and strain equivalent assumption, size effect and damage are taken into consideration in the present model. The dynamic governing partial differential equations of the microplate system were obtained using Hamilton’s principle and solved using the harmonic balance method after they are transformed into ordinary differential equation with regard to time. Size effect and damage effect on nonlinear free vibration of the microplate under DC voltage are discussed using frequency-response curve. In the forced vibration analysis, the frequency-response curves were also employed for the purpose of highlighting the influence of different physical parameters such as external excitation, damping coefficient, material length scale parameter, and damage variable when the system is under AC voltage. The results presented in this study may be helpful and useful for the dynamic stability of a electrically actuated microplate system.


Author(s):  
S. A. M. Lajimi ◽  
G. R. Heppler ◽  
E. Abdel-Rahman

The nonlinear dynamics of a cantilever-beam-rigid-body MEMS gyroscope near primary resonance are studied by using a shooting method and long time integration. The microsensor includes a square beam carrying an eccentric end-rigid-body rotating about the longitudinal axis and under an electrostatic force. The mathematical model of the system is reduced by using the method of assumed modes. Using a shooting method and long time integration, the dynamic characteristics of the system are investigated and presented in terms of frequency-response plots and force-response curves. The bifurcation points are discussed and the regions of instability are characterized.


Author(s):  
Mohammad A. Bukhari ◽  
Oumar R. Barry

This paper presents the nonlinear vibration of a simply supported Euler-Bernoulli beam with a mass-spring system subjected to a primary resonance excitation. The nonlinearity is due to the mid-plane stretching and cubic spring stiffness. The equations of motion and the boundary conditions are derived using Hamiltons principle. The nonlinear system of equations are solved using the method of multiple scales. Explicit expressions are obtained for the mode shapes, natural frequencies, nonlinear frequencies, and frequency response curves. The validity of the results is demonstrated via comparison with results in the literature. Exact natural frequencies are obtained for different locations, rotational inertias, and masses.


Author(s):  
Andrea Arena ◽  
Giovanni Formica ◽  
Walter Lacarbonara ◽  
Harry Dankowicz

A computational framework is proposed to path follow the periodic solutions of nonlinear spatially continuous systems and more general coupled multiphysics problems represented by systems of partial differential equations with time-dependent excitations. The set of PDEs is cast in first order differential form (in time) u˙ = f(u,s,t;c) where u(s,t) is the vector collecting all state variables including the velocities/time rates, s is a space coordinate (here, one-dimensional systems are considered without lack of generality for the space dependence) and t denotes time. The vector field f depends, in general, not only on the classical state variables (such as positions and velocities) but also on the space gradients of the leading unknowns. The space gradients are introduced as part of the state variables. This is justified by the mathematical and computational requirements on the continuity in space up to the proper differential order of the space gradients associated with the unknown position vector field. The path following procedure employs, for the computation of the periodic solutions, only the evaluation of the vector field f. This part of the path following procedure within the proposed combined scheme was formerly implemented by Dankowicz and coworkers in a MATLAB software package called COCO. The here proposed procedure seeks to discretize the space dependence of the variables using finite elements based on Lagrangian polynomials which leads to a discrete form of the vector field f. A concurrent bifurcation analysis is carried out by calculating the eigenvalues of the monodromy matrix. A hinged-hinged nonlinear beam subject to a primary-resonance harmonic transverse load or to a parametric-resonance horizontal end displacement is considered as a case study. Some primary-resonance frequency-response curves are calculated along with their stability to assess the convergence of the discretization scheme. The frequency-response curves are shown to be in close agreement with those calculated by direct integration of the PDEs through the FE software called COMSOL Multiphysics. Besides primary-resonance direct forcing conditions, also parametric forcing causing the principal parametric resonance of the lowest two bending modes is considered through construction of the associated transition curves. The proposed approach integrates algorithms from the finite element and bifurcation domains thus enabling an accurate and effective unfolding of the bifurcation and post-bifurcation scenarios of nonautonomous PDEs with the underlying structures.


Author(s):  
D. X. Cao ◽  
S. Leadenham ◽  
A. Erturk

The transformation of waste vibration energy into low-power electricity has been heavily researched to enable self-sustained wireless electronic components. Monostable and bistable nonlinear oscillators have been explored by several researchers in an effort to enhance the frequency bandwidth of operation. Linear two degree of freedom (2-DOF) configurations as well as combination of a nonlinear single-DOF harvester with a linear oscillator to constitute a nonlinear 2-DOF harvester have also been explored to develop broadband energy harvesters. In the present work, the concept of nonlinear internal resonance in a continuous frame structure is explored for broadband energy harvesting. The L-shaped beam-mass structure with quadratic nonlinearity was formerly studied in the nonlinear dynamics literature to demonstrate modal energy exchange and the saturation phenomenon when carefully tuned for two-to-one internal resonance. In the current effort, piezoelectric coupling is introduced, and electromechanical equations of the L-shaped energy harvester are employed to explore the primary resonance behaviors around the first and the second linear natural frequencies for bandwidth enhancement. Simulations using approximate analytical frequency response equations as well as time-domain numerical solutions reveal that 2-DOF configuration with quadratic and two-to-one internal resonance could extend the bandwidth enhancement capability. Both electrical power and shunted vibration frequency response curves of steady-state solutions are explored in detail. Effects of various electromechanical system parameters, such as piezoelectric coupling and load resistance, on the overall dynamics of the internal resonance energy harvesting system are reported.


2015 ◽  
Vol 23 (17) ◽  
pp. 2742-2756 ◽  
Author(s):  
RK Mitra ◽  
S Chatterjee ◽  
AK Banik

The Duffing oscillator under time-delayed displacement feedback is investigated to study the effect of intentional time-delay on the global dynamics of the oscillator. From the free vibration study performed by employing the describing function method it is observed that for the undamped oscillator, an infinite number of limit cycles is present for all possible values of gain and delay. The number of stable and unstable limit cycles in the gain versus delay plane is studied region wise with the help of limit cycle stability lines. Secondly, in a damped system, the number of limit cycles is finite and depends upon the values of gain, delay and damping coefficient from which the maximum number of limit cycles, their frequencies and amplitudes are obtained. When the system is excited by harmonic forcing, these limit cycles exhibit the phenomena of multiple entrainments and their frequency response curves become very complex and most often results in the very high amplitude oscillations. The study of the forced damped oscillator is therefore carried out by applying the method of slowly varying parameter and the frequency response curves for period-1 responses are analyzed. Further, with the a priori knowledge of possible stable and unstable limit cycles obtained by the application of semi-analytical methods, the various instability phenomena due to subharmonic and quasiperiodic responses have also been investigated by numerical simulation using Simulink in the different parametric ranges.


2021 ◽  
Vol 11 (20) ◽  
pp. 9486
Author(s):  
Andrea Arena

The nonlinear dynamic features of compression roller batteries were investigated together with their nonlinear response to primary resonance excitation and to internal interactions between modes. Starting from a parametric nonlinear model based on a previously developed Lagrangian formulation, asymptotic treatment of the equations of motion was first performed to characterize the nonlinearity of the lowest nonlinear normal modes of the system. They were found to be characterized by a softening nonlinearity associated with the stiffness terms. Subsequently, a direct time integration of the equations of motion was performed to compute the frequency response curves (FRCs) when the system is subjected to direct harmonic excitations causing the primary resonance of the lowest skew-symmetric mode shape. The method of multiple scales was then employed to study the bifurcation behavior and deliver closed-form expressions of the FRCs and of the loci of the fold bifurcation points, which provide the stability regions of the system. Furthermore, conditions for the onset of internal resonances between the lowest roller battery modes were found, and a 2:1 resonance between the third and first modes of the system was investigated in the case of harmonic excitation having a frequency close to the first mode and the third mode, respectively.


2021 ◽  
Author(s):  
Wei Li ◽  
Hong-Yan Chen ◽  
Hong Yang

Abstract In this paper, the nonlinear dynamic characteristics of statically piezoelectric actuated vibrating beam micro-gyroscopes are studied. The comprehensive nonlinear model including curvature, inertia and electrostatic force nonlinearities is considered. In the research of electrostatic micro-gyroscopes, it’s a novel way to tune the primary resonance by piezoelectric actuation and multiple nonlinearities. The multiple scales method and numerical continuation technique are used to characterize the frequency-amplitude and force-amplitude responses of the micro-gyroscopes. The effect of varying the size-dependent, fringing field, statically piezoelectric voltage and nonlinear curvature and inertia on the dynamic response of the micro-gyroscope is investigated in detail. The frequency-response results show that small vibrations produce a symmetrical frequency response curve in sense direction while the system actually has a significant softening characteristic in drive direction. The nonlinear multi-value problem effectively reduces in sense direction under the size-dependent effect, which plays an important role in the design of detection instruments for micro-gyroscopes. Choosing a positive piezoelectric actuation voltage will obtain a higher sensitivity. Increasing the curvature nonlinearity and reducing the inertial nonlinearity of the gyroscopic system will help the micro-gyroscope obtain better sensitivity, and may eliminate multi-valued responses as much as possible.


Sign in / Sign up

Export Citation Format

Share Document