scholarly journals Revisiting the Instability and Bifurcation Behavior of Soft Dielectrics

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Shengyou Yang ◽  
Xuanhe Zhao ◽  
Pradeep Sharma
Keyword(s):  
Aspect Ratio ◽  
Electric Field ◽  
Dielectric Material ◽  
Stretchable Electronics ◽  
Closed Form Solutions ◽  
Homogeneous Half Space ◽  
Highly Nonlinear ◽  
Soft Dielectrics ◽  
Electrical Stimuli ◽  
Bifurcation Behavior

Development of soft electromechanical materials is critical for several tantalizing applications such as human-like robots, stretchable electronics, actuators, energy harvesting, among others. Soft dielectrics can be easily deformed by an electric field through the so-called electrostatic Maxwell stress. The highly nonlinear coupling between the mechanical and electrical effects in soft dielectrics gives rise to a rich variety of instability and bifurcation behavior. Depending upon the context, instabilities can either be detrimental, or more intriguingly, exploited for enhanced multifunctional behavior. In this work, we revisit the instability and bifurcation behavior of a finite block made of a soft dielectric material that is simultaneously subjected to both mechanical and electrical stimuli. An excellent literature already exists that has addressed the same topic. However, barring a few exceptions, most works have focused on the consideration of homogeneous deformation and accordingly, relatively fewer insights are at hand regarding the compressive stress state. In our work, we allow for fairly general and inhomogeneous deformation modes and, in the case of a neo-Hookean material, present closed-form solutions to the instability and bifurcation behavior of soft dielectrics. Our results, in the asymptotic limit of large aspect ratio, agree well with Euler's prediction for the buckling of a slender block and, furthermore, in the limit of zero aspect ratio are the same as Biot's critical strain of surface instability of a compressed homogeneous half-space of a neo-Hookean material. A key physical insight that emerges from our analysis is that soft dielectrics can be used as actuators within an expanded range of electric field than hitherto believed.

Mathematical model to predict the characteristics of polarization in dielectric materials: The concept of piezoelectrcity and electrostriction

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Mathematical Model ◽  
Electric Field ◽  
Lead Zirconate Titanate ◽  
Dielectric Material ◽  
Strain Curve ◽  
Dielectric Materials ◽  
Lead Zirconate ◽  
Simulation Software ◽  
Constitutive Law ◽  
Basic Material

Model was developed for the prediction of polarization characteristics in a dielectric material exhibiting piezoelectricity and electrostriction based on mathematical equations and MATLAB computer simulation software. The model was developed based on equations of polarization and piezoelectric constitutive law and the functional coefficient of Lead Zirconate Titanate (PZT) crystal material used was 2.3×10-6 m (thickness), the model further allows the input of basic material and calculation of parameters of applied voltage levels, applied stress, pressure, dielectric material properties and so on, to generate the polarization curve, strain curve and the expected deformation change in the material length charts. The mathematical model revealed that an application of 5 volts across the terminals of a 2.3×10-6 m thick dielectric material (PZT) predicted a 1.95×10-9 m change in length of the material, which indicates piezoelectric properties. Both polarization and electric field curve as well as strain and voltage curve were also generated and the result revealed a linear proportionality of the compared parameters, indicating a resultant increase in the electric field yields higher polarization of the dielectric materials atmosphere.

High Aspect Ratio Tilted Gratings Through Local Electric Field Modulation in Plasma Etching

2021 ◽  
Author(s):  
Zhitian Shi ◽  
Konstantins Jefimovs ◽  
Antonino La Magna ◽  
Marco Stampanoni ◽  
Lucia Romano
Keyword(s):  
Aspect Ratio ◽  
Electric Field ◽  
Plasma Etching ◽  
High Aspect Ratio ◽  
Local Electric Field ◽  
Field Modulation

scholarly journals Size Distribution, Mechanical and Electrical Properties of CuO Nanowires Grown by Modified Thermal Oxidation Methods

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1051 ◽  
Author(s):  
Raitis Sondors ◽  
Jelena Kosmaca ◽  
Gunta Kunakova ◽  
Liga Jasulaneca ◽  
Matiss Martins Ramma ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Aspect Ratio ◽  
Electric Field ◽  
Thermal Oxidation ◽  
Size Distribution ◽  
High Aspect Ratio ◽  
Growth Conditions ◽  
Cuo Nanowires ◽  
Young’S Moduli ◽  
Order Of Magnitude

Size distribution, Young’s moduli and electrical resistivity are investigated for CuO nanowires synthesized by different thermal oxidation methods. Oxidation in dry and wet air were applied for synthesis both with and without an external electrical field. An increased yield of high aspect ratio nanowires with diameters below 100 nm is achieved by combining applied electric field and growth conditions with additional water vapour at the first stage of synthesis. Young’s moduli determined from resonance and bending experiments show similar diameter dependencies and increase above 200 GPa for nanowires with diameters narrower than 50 nm. The nanowires synthesized by simple thermal oxidation possess electrical resistivities about one order of magnitude lower than the nanowires synthesized by electric field assisted approach in wet air. The high aspect ratio, mechanical strength and robust electrical properties suggest CuO nanowires as promising candidates for NEMS actuators.

Absolute Nodal Coordinate Formulation With Vector-Strain Transformation for High Aspect Ratio Wings

2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Keisuke Otsuka ◽  
Yinan Wang ◽  
Kanjuro Makihara
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Degrees Of Freedom ◽  
Absolute Nodal Coordinate Formulation ◽  
Lattice Method ◽  
Absolute Nodal Coordinate ◽  
Aeroelastic Analysis ◽  
Strain Transformation ◽  
Highly Nonlinear ◽  
Analytical Approaches

Abstract High aspect ratio wings are potential candidates for use in atmospheric satellites and civil aircraft as they exhibit a low induced drag, which can reduce the fuel consumption. Owing to their slender and light weight configuration, such wings undergo highly flexible aeroelastic static and dynamic deformations that cannot be analyzed using conventional linear analysis methods. An aeroelastic analysis framework based on the absolute nodal coordinate formulation (ANCF) can be used to analyze the static and dynamic deformations of high aspect ratio wings. However, owing to the highly nonlinear elastic force, the statically deformed wing shape during steady flight cannot be efficiently obtained via static analyses. Therefore, an ANCF with a vector-strain transformation (ANCF-VST) was proposed in this work. Considering the slender geometry of high aspect ratio wings, the nodal vectors of an ANCF beam element were transformed to the strains. In this manner, a constant stiffness matrix and reduced degrees-of-freedom could be generated while capturing the highly flexible deformations accurately. The ANCF-VST exhibited superior convergence performance and accuracy compared to those of analytical approaches and other nonlinear beam formulations. Moreover, an aeroelastic analysis flow coupling the ANCF-VST and an aerodynamic model based on the unsteady vortex lattice method was proposed to perform the static and dynamic analyses successively. The proposed and existing aeroelastic frameworks exhibited a good agreement in the analyses, which demonstrated the feasibility of employing the proposed framework to analyze high aspect ratio wings.

Fast Ion Loss and Radial Electric Field in High-Aspect-Ratio Stellarator

1992 ◽  
Vol 61 (7) ◽  
pp. 2294-2303 ◽  
Author(s):  
Kimitaka Itoh ◽  
Heiji Sanuki ◽  
Sanae-I. Itoh
Keyword(s):  
Aspect Ratio ◽  
Electric Field ◽  
High Aspect Ratio ◽  
Radial Electric Field ◽  
Fast Ion

Synthesis of Seven-Link Mechanisms

1973 ◽  
Vol 95 (2) ◽  
pp. 533-540 ◽  
Author(s):  
D. Kohli ◽  
A. H. Soni
Keyword(s):  
Closed Form ◽  
Nonlinear Equations ◽  
Degrees Of Freedom ◽  
The Other ◽  
Linear Superposition ◽  
Two Degrees Of Freedom ◽  
Closed Form Solutions ◽  
Highly Nonlinear ◽  
Principle Of Linear Superposition

The mechanisms derived from the seven-link chains with five links in their two loops and having two degrees of freedom are examined for six synthesis problems. Using displacement matrices, closed form synthesis equations are derived. It is shown that three synthesis problems may be solved using the principle of linear superposition, and closed form solutions may be obtained. The other three synthesis problems involve highly nonlinear equations and must be solved numerically.

Electrochemical Influence of Collagen Piezoelectric Effect in Bone Healing

2007 ◽  
Vol 544-545 ◽  
pp. 981-984 ◽  
Author(s):  
Karem Noris-Suárez ◽  
Joaquín Lira-Olivares ◽  
Ana M. Ferreira ◽  
Armando Graterol ◽  
Jose L. Feijoo ◽  
...  
Keyword(s):  
Electric Field ◽  
Bone Healing ◽  
Bone Growth ◽  
Piezoelectric Effect ◽  
Osteoblastic Activity ◽  
Electrical Stimuli ◽  
Biomimetic Deposition

Bone healing and growth are controlled by the rate of deposition of hidroxiapatite (HA). This process have been so far accredited to the work of osteoblasts, which are attracted by the electrical dipoles produced either by piezoelectricity, due to deformation of the bone, specially the collagen in it, or due to outside electrical stimuli. The present work shows that even without osteoblasts present, the piezoelectric dipoles produced by deformed collagen, can produce the precipitation of HA by electrochemical means, without catalyzer as in biomimetic deposition. These findings could clarify the contribution of osteoblasts in bone growth as compared to the electrochemical action by itself. Further studies ascertaining the osteoblastic activity due to the electric field are being advanced.

Intelligent PID Control and the Bifucation Behavior of Hydrogenerator Set

2014 ◽  
Vol 494-495 ◽  
pp. 1702-1705
Author(s):  
Zhong Liao ◽  
Chun Dan Song
Keyword(s):  
Pid Control ◽  
Complex Dynamics ◽  
Intelligent System ◽  
Nonlinear Differential Equations ◽  
Nonlinear Dynamical ◽  
Supercritical Bifurcation ◽  
Set Systems ◽  
Highly Nonlinear ◽  
Intelligent Pid ◽  
Bifurcation Behavior

.Considering of the highly nonlinear, time-variable and complex dynamics and the easy variance of hydrogenerator set systems structure and parameters, a nonlinear dynamical model is presented, which can be analyzed by the bifurcation theory of nonlinear differential equations and simulated in computer. By using the genetic algorithm, the PID parameters of hydrogenerator set intelligent system are optimized and the control performances are improved. The algebra criterion about the existence of bifurcation is employed to study the bifurcation behavior of the nonlinear model which takes the PID parameters as the bifurcation ones. The simulations show that a supercritical bifurcation is likely to exist in hydrogenerator set system and the bifurcation will occur for the higher values of PID parameters. Theory and simulation results of this paper can be considered as good suggest for intelligent PID control system of hydrogenerator set system.

Analysis of nonlinear electric field of hvdc wall bushing with a finite element approach

Open Physics ◽  
2005 ◽  
Vol 3 (4) ◽  
Author(s):  
Liming Dai ◽  
Longfu Luo
Keyword(s):  
Finite Element ◽  
Electric Field ◽  
High Voltage ◽  
Element Analysis ◽  
Nonlinear Characteristics ◽  
High Voltage Direct Current ◽  
Numerical Iteration ◽  
Numerical Assessment ◽  
Highly Nonlinear ◽  
Element Approach

AbstractThe present research intends to establish a numerical model, on the basis of a theoretical analysis, for describing and analyzing the electric field of High Voltage Direct Current (HVDC) wall bushing that demonstrates highly nonlinear characteristics. The wall bushing is subjected high voltage with nonlinear electric field and the relationship between the electric field intensity and the resistance of the insulators of the wall bushing is highly nonlinear. With a parameter design language of a Finite Element Analysis software package for carrying out the numerical calculations, the effects of the nonlinearity on the electric field can be well taken into consideration in performing the numerical assessment. A technique utilizing the numerical iteration is developed for quantifying the electric intensity of the electric field. With the model and the iteration technique established, the nonlinear characteristics of the HVDC wall bushing can be investigated with efficiency.

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