On Nonlinear Dynamics of Nanotweezers

Author(s):  
Dumitru I. Caruntu ◽  
Bin Liu

This paper deals with amplitude-frequency response of electrostatic nanotube nanotweezer device system. Soft alternating current (AC) of frequency near natural frequency actuates the nanotubes. This leads the system into parametric resonance. The Method of Multiple Scales (MMS) in which the nonlinear electrostatic and van der Waals forces are expanded in Taylor series is used to compare two expansions, one up to third power and the other up to fifth power. The frequency response of the system is reported and the effects of van der Waals forces, electrostatic forces, and damping forces on the frequency response are investigated.

Author(s):  
Julio Beatriz ◽  
Dumitru I. Caruntu

Abstract In this paper, the Method of Multiple Scales, and the Reduced Order Model method of two modes of vibration are used to investigate the amplitude-frequency response of parametric resonance of electrostatically actuated circular plates under hard excitations. Results show that the Method of Multiple Scales is accurate for low voltages. However, it starts to separate from the Reduced Order Model results as the voltage values are larger. The Method of Multiple Scales is good for low amplitudes and weak non-linearities. Furthermore the Reduced Order Model running with AUTO 07p is validated and calibrated using the 2 Term ROM time responses.


Author(s):  
Julio Beatriz ◽  
Martin Botello ◽  
Christian Reyes ◽  
Dumitru I. Caruntu

This paper deals with two different methods to analyze the amplitude frequency response of an electrostatically actuated micro resonator. The methods used in this paper are the method of multiple scales, which is an analytical method with one mode of vibration. The other method is based on system of odes which is derived using the partial differential equation of motion, as well as the boundary conditions. This system is then solved using a built in matlab function known as BVP4C. Results are then shown comparing the two methods, under a variety of parameters, including the influence of damping, voltage, and fringe.


Author(s):  
Dumitru I. Caruntu ◽  
Ezequiel Juarez

Abstract This paper deals with electrostatically actuated Double-Walled Carbon Nanotubes (DWCNT) and Single-Walled Carbon Nanotubes (SWCNT) cantilever resonators. Frequency response of parametric resonance is investigated. Euler-Bernoulli cantilever beam model is used for both DWCNT and SWCNT. Electrostatic and viscous damping forces are applied on both types of resonators, DWCNT and SWCNT. In this investigation, soft AC voltage excitation is assumed. For the DWCNT, an intertube van der Waals force is present between the two concentric carbon nanotubes (CNTs), coupling their motion and acting as a nonlinear spring. The nonlinearities in the vibration are provided by the electrostatic (both SWCNT and DWCNT) and intertube van der Waals forces (DWCNT). The Method of Multiple Scales (MMS) is a perturbation method that provides uniformly valid approximations for weakly nonlinear systems. A Reduced-Order-Model (ROM) is developed and numerically solved using AUTO-07P (bifurcation and continuation software). Since large tip deflections are investigated in this paper, only coaxial vibration of the DWCNT is considered. Parametric resonance is investigated, as well as the influences of damping and voltage. Lastly, the effect of intertube van der Waals force on the bifurcation and stability of the DWCNT is reported.


Author(s):  
Christopher Reyes ◽  
Dumitru I. Caruntu

The purpose of this paper is to investigate the nonlinear dynamics governing the behavior of electrostatically actuated micro electro mechanical systems (MEMS) cantilever undergoing parametric resonance. The MEMS consists of a cantilever parallel to a ground plate. The beam is actuated via an A/C voltage with excitation frequency near first natural frequency of the cantilever. The model includes damping, electrostatic, and Casimir (or van der Waals) forces. The electrostatic force is modeled to include the fringe effect. The amplitude-voltage response of the parametric resonance and the effects of varying the magnitudes of the fringe, Casimir (or Van der Waals), and damping forces along with varying the detuning parameter are reported. The response is obtained using two different methods, namely the method of multiple scales (MMS), and the homotopy analysis method (HAM). In this study approximations up to a 2nd order HAM are used. HAM is a deformation technique that begins with an initial guess and continuously deforms it to the exact answer. For the 1st Order HAM, a softening effect is reported. The 1st Order HAM matches the MMS results in low amplitude and begins to soften and deviate away from the MMS solution in higher amplitudes. For the 2nd Order HAM deformation the softening effect is slightly more pronounced with a slightly lower prediction of the maximum deflection of the cantilever tip. For the 2nd order deformation solution the stable branch of the amplitude-voltage response obtained by the HAM shifts leftward from the MMS solution with the unstable branches between the two methods continue to agree in low amplitudes and deviate in high amplitudes. As a remark, the higher order HAM solutions are obtained symbolically with the software Mathematica and numerically ran with the software Matlab.


Author(s):  
Dumitru I. Caruntu ◽  
Ezequiel Juarez

This paper deals with electrostatically actuated Double Walled Carbon Nanotubes (DWCNT) cantilevered resonators. The governing equations for the motion of the DWCNT are derived through Euler-Bernoulli beam model assumptions that account for inertial and viscoelastic effects. The DWCNT is a specific type of multi-walled carbon nanotube (MWCNT) that is comprised of two coaxially concentric carbon nanotubes. Electrostatic, damping, and intertube van der Waals forces act on the outer tube of the DWCNT, while only intertube van der Waals force acts on the inner tube. A soft AC voltage provides the electrostatic actuation. The nonlinear behavior and phenomena in the system are provided by the electrostatic and intertube van der Waals forces. The DWCNT is subjected to nonlinear parametric dynamics. The Method of Multiple Scales (MMS) is employed to investigate the system under soft excitations and/or weak nonlinearities. The frequency-amplitude response is found in the case of parametric resonance. The resulting nonlinear dynamic behavior is important to improve DWCNT resonator sensitivity in the application of mass sensing.


Author(s):  
Dumitru I. Caruntu ◽  
Israel Martinez ◽  
Martin W. Knecht

This paper uses the Reduced Order Model (ROM) method to investigate the influence of nonlinearities from parametric electrostatic excitation due to soft AC voltage of frequency near half natural frequency of the MEMS cantilever resonator on its frequency response. Most of the analysis in literature investigates pull-in phenomenon, stability, amplitude–frequency relations, or finds time responses of such systems. In this work it is showed that the bifurcation points in the amplitude-frequency response occur at lower frequencies and amplitudes than predicted by the Method of Multiple Scales (MMS), a perturbation method. This result is extremely important for predicting pull-in phenomena. Also the ROM predicts pull-in instability for large initial amplitudes and AC frequencies less than half natural frequency of the resonator. MMS fails to predict this behavior. Increasing the damping and/or decreasing the voltage increases the frequency at which the system undergoes into a pull-in phenomenon.


2021 ◽  
Author(s):  
Dumitru I. Caruntu ◽  
Julio Beatriz ◽  
Miguel Martinez

Abstract This work deals with the amplitude-frequency response subharmonic resonance of 1/4 order of electrostatically actuated circular plates. The method of multiple scales is used to model the hard excitations and to predict the response. This work predicts that the steady state solutions are zero amplitude solutions, and non-zero amplitude solutions which consist of stable and unstable branches. The effects of parameters such as voltage and damping on the response are predicted. As the voltage increases, the non-zero amplitude solutions are shifted to lower frequencies. As the damping increases, the non-zero steady-state amplitudes are shifted to higher amplitudes, so larger initial amplitudes for the MEMS plate to reach non-zero steady-state amplitudes.


Author(s):  
Dumitru I. Caruntu ◽  
Reynaldo Oyervides

This paper deals with Casimir and van der Waals effects on the frequency response of parametric resonance of electrostatically actuated NEMS circular plates for bio-sensing applications. The bio-NEMS resonator consists of a clamped circular elastic plate over a fixed electrode plate. A soft AC voltage of frequency near natural frequency between the plates gives an electrostatic force that leads the elastic plate into vibration which leads to parametric resonance that can be used afterwards for biosensing purposes. Frequency response and the effects of Casimir, and van der Waals forces on the response are reported.


Author(s):  
Cheng-Kuo Sung ◽  
Paul C. P. Chao ◽  
Ben-Cheng Yo

This study is devoted to explore the effect of nonlinear dynamics of damping washers on the dynamic performance of automatic ball balancer (ABB) system installed in optical disc drives. The ABB is generally used on rotational system to reduce vibration. Researches have been conducted to study the performance of the ABB by investigating the nonlinear dynamics of the system; however, the model adopted often consider the damping washer in a typical ABB suspension system as a linear one, which does not reflect the fact that the practical washers are inevitably exhibit nontrivial nonlinear dynamics at some range of operation, deviating the ABB performance away from the expecteds. In this study, a complete dynamic model of the ABB including a detailed nonlinear model of the damping washers based on experimental data for practical wahers is established. The method of multiple scales is then applied to formulate a scaled model to find all possible steady-state ball positions and analyze stabilities. It is found that with reasonable level of nonlinearity, the balancing balls of the ABB are still reside at the desired positions at steady state, rendering expected vibration reduction; however, jump phenomena also occurs as the spindle operated through natural frequency of the suspension, causing unwanted system vibrations. Numerical simulations and experiments are conducted to verify the theoretical findings. The obtained results are used to predict the level of residual vibration, with which the guidelines on choices of the nonlinear damping washers are distilled to achieve desired performance.


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