scholarly journals Modal Coupling Effect in a Novel Nonlinear Micromechanical Resonator

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 472
Author(s):  
Kuo Lu ◽  
Qingsong Li ◽  
Xin Zhou ◽  
Guoxiong Song ◽  
Kai Wu ◽  
...  
Keyword(s):  
Cavity Mode ◽  
Coupling Effect ◽  
Micromechanical Resonators ◽  
Mechanical Coupling ◽  
Wide Range ◽  
Modal Coupling ◽  
Dynamical Coupling ◽  
Electrostatic Coupling ◽  
Stiffness Softening ◽  
Hardening Condition

Capacitive micromechanical resonators share electrodes with the same bias voltage, resulting in the occurrence of electrostatic coupling between intrinsic modes. Unlike the traditional mechanical coupling, the electrostatic coupling is determined by the structural electric potential energy, and generally, it only occurs when the coupling modes operate in nonlinear regions. However, previous electrostatic coupling studies mainly focus on the stiffness softening region, with little attention on the opposite stiffness hardening condition. This paper presents a study on the electrostatic modal coupling effect in the stiffness hardening region. A novel capacitive micromechanical resonator with different modal nonlinearities is designed and fabricated. It is demonstrated that activating a cavity mode can shift the fundamental resonance of the manipulated mode by nearly 90 times its mechanical bandwidth. Moreover, the frequency shifting direction is found to be related to the manipulated mode’s nonlinearity, while the frequency hopscotch is determined by the cavity mode’s nonlinearity. The electrostatic coupling has been proven to be an efficient and tunable dynamical coupling with great potential for tuning the frequency in a wide range. The modal coupling theory displayed in this paper is suitable for most capacitive resonators and can be used to improve the resonator’s performance.

Analysis of the Electro-Mechanical Responses of the Piezoelectric Motor Based on Finite Element Method

2014 ◽  
Vol 697 ◽  
pp. 181-186
Author(s):  
Zi Lei Wang ◽  
Tian De Qiu
Keyword(s):  
Finite Element ◽  
Coupling Effect ◽  
Complex Stress ◽  
Piezoelectric Resonator ◽  
Element Analysis ◽  
Mechanical Coupling ◽  
Mechanical Responses ◽  
Stress Boundary Condition ◽  
Piezoelectric Field ◽  
Stress Boundary

The piezoelectric field and structure field of piezoelectric resonator of ultrasonic motor are intercoupling. It is difficult to obtain the solution under some circumstances because of the complex stress boundary condition and the influence of coupling effect. An electro-mechanical coupling finite-element dynamic equation is established on the basis of the Hamilton’s Principle about piezoceramic and elastomer. The equation is decoupled through the shock excitation of the piezoelectric resonator and the piezoelectricity element and material provided by finite-element analysis. As a result, an admittance curve as well as the distribution status of the nodal DOF is obtained, which provides an effective method to solve electro-mechanical coupling problems.

Improved Structural Design and Digital Control System for Micro-Machined Tuning Fork Gyroscope

2011 ◽  
Vol 383-390 ◽  
pp. 5997-6002
Author(s):  
Jiao Wen ◽  
Xiao Ming Liu ◽  
Zhong Gan Zhu ◽  
Ming Cai
Keyword(s):  
Control System ◽  
Structural Design ◽  
Digital Control ◽  
Analog Circuit ◽  
Tuning Fork ◽  
Coupling Effect ◽  
Digital Control System ◽  
Mechanical Coupling ◽  
Spring Suspension ◽  
Improved Design

This paper proposes an improved design of micro-machined tuning fork gyroscope (M-TFG) to better decouple the cross talk between the driving and sensing directions and to increase resolution. By employing dual-folds spring suspension, the drive mode and the sense mode are mechanically decoupled. Through careful layout design of the location of the dual-folds spring suspension and the drive combs, the mechanical coupling effect is further decreased by isolating the unwanted excitation from detection. The peripheral circuit is also the important part to realize the function of the gyro system. Since the analog circuit has some inherent shortcomings, which has limited the accuracy of the gyro. In this paper, a digital control system for micro-comb is introduced.

Development of Numerical Code for Coupling Dynamical Response of Typical Tokomak Structures Using Volumetric Finite Element

2013 ◽  
Author(s):  
Zhensheng Yuan ◽  
Weixin Li ◽  
Jingyi Xu ◽  
Wenjing Wu ◽  
Zhenmao Chen
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Coupling Effect ◽  
Time Integration ◽  
Numerical Code ◽  
Dynamical Response ◽  
Vacuum Vessel ◽  
Integration Algorithm ◽  
Simulation Accuracy ◽  
Mechanical Coupling

Aiming to simulate the dynamical response of a non-ferromagnetic conductive structure in a strong magnetic field, a code of finite element method (FEM) was developed based on the reduced vector potential (Ar) method and a step by step time integration algorithm. The electromagneto-mechanical coupling effect was taken into consideration by adding ν × B term in the eddy current governing equation to calculate the additional electric field induced by the movement of the structure. The hexahedral isoparametric element was adopted in this code in order to simplify the correspondence between the simulation of electromagnetic force and the dynamical response, which enables the application of the code developed by authors to more complicated structures. To verify the validity of the new numerical code, the benchmark problem (TEAM-16) as a simplified model of Tokamak vacuum vessel structure was simulated. By numerical results contrasted between the current code and the ANSYS software, the code was proved to be more effective than typical commercial codes for structural analysis of a magneto-mechanical coupling problem. The simulation results proved that the new code can improve simulation accuracy especially in case of a large external magnetic field. In addition, the magnetic damping effect was also discussed in the paper.

AN APPROXIMATION METHOD FOR COMPUTING THE DYNAMIC RESPONSES AND EQUIVALENT STATIC WIND LOADS OF LARGE-SPAN ROOF STRUCTURES

2010 ◽  
Vol 10 (05) ◽  
pp. 1141-1165 ◽  
Author(s):  
XUANYI ZHOU ◽  
MING GU
Keyword(s):  
Coupling Effect ◽  
Coupling Factor ◽  
Dynamic Responses ◽  
Wind Loads ◽  
Inertia Force ◽  
Large Span ◽  
Load Distributions ◽  
Modal Coupling ◽  
Vibration Responses ◽  
Equivalent Static Wind Loads

Due to their sensitivity to wind, the design of large-span roofs is generally governed by wind loads. For some flexible large-span roofs with low damping and concentrated modes, the effect of multi-mode coupling should be taken into account in computing the resonant buffeting response and equivalent static wind loads. Such an effect is considered by the modified SRSS method in this paper via the modal coupling factor. Based on the same SRSS method, the equivalent static wind loads combining the mean, background, and resonant components, are computed. Particularly, the background and resonant components are computed by the LRC method and the equivalent inertia force method considering the modal coupling effects by the modified SRSS method, respectively. The method is then applied to the computation of wind-induced vibration responses and equivalent static wind load distributions of a real large-span roof. The results show that the modal coupling effect on the resonant component can be identified by the present method with high accuracy.

Electronic and Mechanical Coupling in Elastically Bent ZnO Micro/Nanowires

2014 ◽  
Vol 1664 ◽  
Author(s):  
Xuewen Fu ◽  
Zhimin Liao ◽  
Dapeng Yu
Keyword(s):  
Elastic Strain ◽  
Electronic Band Structure ◽  
Coupling Effect ◽  
Low Cost ◽  
Chemical Properties ◽  
Strain Engineering ◽  
Near Band Edge ◽  
Engineering Strain ◽  
Electronic Band ◽  
Mechanical Coupling

ABSTRACTElastic engineering strain has been regarded as a low-cost and continuously variable manner for altering the physical and chemical properties of materials, and it becomes even more important at low-dimensionality because at micro/nanoscale, materials/structures can usually bear exceptionally high elastic strains before failure. The elastic strain effects are therefore greatly magnified in micro/nanoscale structures and should be of great potential in the design of novel functional devices. The purpose of this overview is to present a summary of our recently progress in the energy band engineering of elastically bent ZnO micro/nanowires. First, we present the electronic and mechanical coupling effect in bent ZnO nanowires. Second, we summary the bending strain gradient effect on the near-band-edge (NBE) emission photon energy of bent ZnO micro/nanowires. Third, we show that the strain can induce exciton fine-structure splitting and shift in ZnO microwires. Our recent progresses illustrate that the electronic band structure of ZnO micro/nanowires can be dramatically tuned by elastic strain engineering, and point to potential future applications based on the elastic strain engineering of ZnO micro/nanowires.

Influence of temperature and strain rate on the longitudinal compressive crashworthiness of 3D braided composite tubes and finite element analysis

2016 ◽  
Vol 26 (7) ◽  
pp. 1003-1027 ◽  
Author(s):  
Xianyan Wu ◽  
Qian Zhang ◽  
Bohong Gu ◽  
Baozhong Sun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Strain Rate ◽  
Coupling Effect ◽  
Three Dimensional ◽  
Composite Tubes ◽  
Element Analysis ◽  
Impact Compression ◽  
Mechanical Coupling ◽  
The Impact

This article reports the longitudinal compressive crashworthiness of three-dimensional four-step circular braided carbon/epoxy composite tubes at temperatures of 23, −50, and −100℃ under strain rate ranging from 340 to 760/s both experimentally and finite element analysis. The experimental results showed that the compression strength, stiffness, and specific energy absorption increased with the decrease in temperature and with the increase in strain rate. It also showed that, the compressive damage morphologies were sensitive to the change in temperature and strain rate. A coupled thermal-mechanical numerical analysis was conducted to find the thermo/mechanical coupling effect on the compressive crashworthiness of the three-dimensional composite tube. The temperature distributions in the braided preform and the resin during the impact compression were also calculated through finite element analysis. From the finite element analysis results, the inelastic heat generation was seen to be more in the preform than the matrix and its distribution and accumulation led to the damage progress along the loading direction.

Synchronous Decoupled Motion Control for Power-Wheelchairs

2012 ◽  
Vol 482-484 ◽  
pp. 1904-1911 ◽  
Author(s):  
Fu Yun Yang ◽  
Mi Ching Tsai
Keyword(s):  
Motion Control ◽  
Coupling Effect ◽  
Mechanical Coupling ◽  
Control Framework ◽  
Control Scheme ◽  
Power Wheelchairs ◽  
Outdoor Environments ◽  
Decoupled Motion ◽  
Classic Approach ◽  
The Mathematical Model

Unanticipated disturbances in outdoor environments are the main impediments to the development of motion control for transmission vehicles. Classical synchronous approaches which neglect the mechanical coupling effect are unsuitable for such types of mechanisms. To address this concern, much effort has been made to overcome such difficulties. A synchronous decoupled control framework was proposed based on the multivariable model, in which a decoupling transformation matrix was adopted for improving the corresponding performance. The concept of the proposed control framework is intuitive and quite straightforward. To demonstrate the capacity of the mathematical model as well as the effectiveness of the control scheme, a power-wheelchair was utilized as an illustrated example, where the synchronous performance can be enhanced by almost 50% as compared to the classic approach.

A Mathematical Thermal Hydraulic-Mechanical Coupling Model for Unsaturated Porous Media

2014 ◽  
Vol 602-605 ◽  
pp. 365-369
Author(s):  
Jun Yan ◽  
Yin Qi Wei ◽  
Hong Cai
Keyword(s):  
Porous Media ◽  
Solid Mechanics ◽  
Coupling Effect ◽  
Coupling Model ◽  
Unsaturated Porous Media ◽  
Liquid Pressure ◽  
Mechanical Coupling ◽  
The Earth ◽  
Highly Nonlinear ◽  
Pore Liquid

s: Temperature, seepage and deformation are the important parts of the engineering geological mechanics both in water conservancy and hydropower engineering since there are highly nonlinear complex coupling effect between each other. In this paper, the earth and rock mass are classified as continuous porous media. The thermal constitutive relation of porous media and motion regularity of pore fluid are deduced from the basic theory of solid mechanics, hydraulics, and thermodynamics. Based on momentum, mass and energy conservation equations, the multi-field controlling equations of unsaturated porous media are given, in which the unknown variables include displacements, pore liquid pressure, pore gas pressure, temperature, and porosity.

Sign in / Sign up

Export Citation Format

Share Document