Characterization and Variational Modeling of Ionic Polymer Transducers

2006 ◽  
Vol 129 (1) ◽  
pp. 113-120 ◽  
Author(s):  
Miles A. Buechler ◽  
Donald J. Leo
Keyword(s):  
Variational Approach ◽  
Electromechanical Coupling ◽  
Structural Model ◽  
A Priori ◽  
Effective Strain ◽  
Polymer Materials ◽  
Beam Model ◽  
Frequency Dependent ◽  
Ionic Polymer ◽  
Material Parameters

Ionomeric polymers are a promising class of intelligent material which exhibit electromechanical coupling similar to that of piezoelectric bimorphs. Ionomeric polymers are much more compliant than piezoelectric ceramics or polymers and have been shown to produce actuation strain on the order of 2% at operating voltages between 1V and 3V (Akle et al., 2004, Proceedings IMECE). Their high compliance is advantageous in low force sensing configurations because ionic polymers have a very little impact on the dynamics of the measured system. Here we present a variational approach to the dynamic modeling of structures which incorporate ionic polymer materials. To demonstrate the method a cantilever beam model is developed using this variational approach. The modeling approach requires a priori knowledge of three empirically determined material properties: elastic modulus, dielectric permittivity, and effective strain coefficient. Previous work by Newbury and Leo has demonstrated that these three parameters are strongly frequency dependent in the range between less than 1Hz to frequencies greater than 1kHz. Combining the frequency-dependent material parameters with the variational method produces a second-order matrix representation of the structure. The frequency dependence of the material parameters is incorporated using a complex-property approach similar to the techniques for modeling viscoelastic materials. A transducer is manufactured and the method of material characterization is applied to determine the mtaerial properties. Additional experiments are performed on this transducer and both the material and structural model are validated. Finally, the model is shown to predict sensing response very well in comparison to experimental results, which supports the use of an energy-based variational approach for modeling ionomeric polymer transducers.

Investigation of Extensional Actuation Strain in Ionomeric Polymer Transducers

Aerospace ◽  
2005 ◽  
Author(s):  
Barbar J. Akle ◽  
Donald J. Leo
Keyword(s):  
Electromechanical Coupling ◽  
Active Material ◽  
Bending Moment ◽  
Sine Wave ◽  
Polymer Materials ◽  
Quadratic Term ◽  
Beam Shape ◽  
Ionic Polymer ◽  
Assembly Method ◽  
Direct Assembly

Ionomeric polymer transducers have received considerable attention in the past ten years due to their ability to generate large bending strain and moderate stress at low applied voltages. Bending transducers made of an ionomeric polymer membrane sandwiched between two flexible electrodes deform through the expansion of one electrode and contraction of the opposite electrode due to cation displacement. This is similar to a bimorph type actuation. In this study we report actuation through the thickness of the membrane, leading to the potential of a new actuation mechanism for ionomeric polymer materials. Several experiments are performed to compare the bending actuation with the extensional actuation capability. The direct assembly method previously developed by the authors is used to fabricate ionic polymer transducers with controlled electrode dimensions and morphology. Electrodes with varying thickness are used to alter thickness of the active material. In the first experiment, the actuators are cut in beam shape and are allowed to bend in cantilever configuration. In the second configuration, bending is constrained by sandwiching the membranes between two solid metal plates and force is measured across the thickness of the actuator. A bimorph model is used to assess the effect of electrode thickness on the strain. An electromechanical coupling model presented by Leo et al. [1] determined the strain in the active areas as a function of the charge. This model is presented with a linear and a quadratic term that produces a 1st harmonic response for a sine wave actuation input. The quadratic term in the strain generates a zero net bending moment for ionic polymer transducers with symmetric electrodes. The linear term is also canceled in extensional actuation for symmetric electrodes. Experimental results demonstrates strain on the order of 110 μstrain in the thickness direction compared to 1700 μstrain peak to peak on the external fibers for the same transducer when it is allowed to bend under +/−2V potential at 0.5 Hz.

Modeling of Electromechanical Transduction in Ionic Polymer Materials

2002 ◽  
Author(s):  
Kenneth Newbury ◽  
Donald J. Leo
Keyword(s):  
Electromechanical Coupling ◽  
Low Voltage ◽  
Linear Equations ◽  
Polymer Materials ◽  
System Level ◽  
Model Parameters ◽  
Symmetric Model ◽  
Sample Length ◽  
Ionic Polymer ◽  
Electromechanical Transduction

A coupled, linear electromechanical model is developed for ionic polymer transducers. The model is based on the linear equations for a piezoelectric material. Integrating the equations over the geometry of the transducer produces a model of the electromechanical coupling of the polymer transducers as a function of fundamental material parameters and geometry. Explicit modeling of electromechanical coupling produces a model that is useful for analyzing sensing or actuation using ionic polymer transducers. Experiments on polymer samples verify the scaling of the model parameters as a function of sample length and width. The results also demonstrate the reciprocity of the electromechanical coupling. The symmetric model is expressed as a linear transformer which can be incorporated into system-level models for design of devices that utilize ionic polymer materials. The model is limited to linear operation at low-voltage with constant levels of material hydration.

scholarly journals Torsional Characteristics of Carbon Nanotubes: Micropolar Elasticity Models and Molecular Dynamics Simulation

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 453
Author(s):  
Razie Izadi ◽  
Meral Tuna ◽  
Patrizia Trovalusci ◽  
Esmaeal Ghavanloo
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Scale Effects ◽  
Couple Stress Theory ◽  
Dynamics Simulation ◽  
Local Theory ◽  
Beam Model ◽  
Specific Class ◽  
Micropolar Theory ◽  
Material Parameters

Efficient application of carbon nanotubes (CNTs) in nano-devices and nano-materials requires comprehensive understanding of their mechanical properties. As observations suggest size dependent behaviour, non-classical theories preserving the memory of body’s internal structure via additional material parameters offer great potential when a continuum modelling is to be preferred. In the present study, micropolar theory of elasticity is adopted due to its peculiar character allowing for incorporation of scale effects through additional kinematic descriptors and work-conjugated stress measures. An optimisation approach is presented to provide unified material parameters for two specific class of single-walled carbon nanotubes (e.g., armchair and zigzag) by minimizing the difference between the apparent shear modulus obtained from molecular dynamics (MD) simulation and micropolar beam model considering both solid and tubular cross-sections. The results clearly reveal that micropolar theory is more suitable compared to internally constraint couple stress theory, due to the essentiality of having skew-symmetric stress and strain measures, as well as to the classical local theory (Cauchy of Grade 1), which cannot accounts for scale effects. To the best of authors’ knowledge, this is the first time that unified material parameters of CNTs are derived through a combined MD-micropolar continuum theory.

Influence of Anisotropic Yield Functions on Parameters of Yoshida-Uemori Model

2013 ◽  
Vol 554-557 ◽  
pp. 2440-2452 ◽  
Author(s):  
Hirotaka Kano ◽  
Jiro Hiramoto ◽  
Toru Inazumi ◽  
Takeshi Uemori ◽  
Fusahito Yoshida
Keyword(s):  
Effective Strain ◽  
Yield Function ◽  
Strain Response ◽  
Material Parameters ◽  
International Conference ◽  
Polynomial Type ◽  
Calculated Stress ◽  
Yield Functions ◽  
Order Polynomial ◽  
Von Mises

Yoshida-Uemori model (Y-U model) can be used with any types of yield functions. The calculated stress strain response will be, however, different depending on the chosen yield function if the yield function and the effective strain definition are inappropriate. Thus several modifications to Y-U model were proposed in the 10th International Conference on Technology of Plasticity. It was ascertained that in the modified Y-U model, the same set of material parameters can be used with von Mises, Hill’s 1948, and Hill’s 1990 yield function. In this study, Yld2000-2d and Yoshida’s 6th-order polynomial type 3D yield function were examined and it was clarified that the same set of Y-U parameters can be used with these yield functions.

Hybrid Actuation in Coupled Ionic / Conducting Polymer Devices

2003 ◽  
Vol 785 ◽  
Author(s):  
Matthew D. Bennett ◽  
Donald J. Leo
Keyword(s):  
Conducting Polymer ◽  
Smart Materials ◽  
Electromechanical Coupling ◽  
Performance Metrics ◽  
Polymer Membrane ◽  
Low Frequencies ◽  
Ionic Polymer ◽  
Polymer Actuators ◽  
Ionic Conducting ◽  
Initial Results

ABSTRACTIonic polymer membrane actuators represent a relatively new and exciting entry into the field of smart materials. Several key limitations of these transducers have prevented them from experiencing widespread use, however. For example, the bandwidth of these devices is limited at very low frequencies by characteristic relaxation and at high frequencies by the low elastic modulus of the polymer. In this paper, an overview of the initial results of work with hybrid ionic / conducting polymer actuators is presented. These hybrid actuators are devices that combine the electromechanical coupling of ionic polymer actuators and conducting polymer actuators into one coupled device. Initial results show that these hybrid devices have the potential to offer marked advantages over traditional ionic polymer membrane transducers, including increased stress and strain generation and higher actuation bandwidth. Details of the preparation of these devices and performance metrics are presented and comparisons to baseline materials are made.

scholarly journals On dynamic interaction between mechanical systems and selected electric motors

2019 ◽  
Vol 285 ◽  
pp. 00018
Author(s):  
Tomasz Szolc ◽  
Robert Konowrocki ◽  
Andrzej Pochanke
Keyword(s):  
Electromechanical Coupling ◽  
Structural Model ◽  
Mechanical Systems ◽  
Dynamic Interaction ◽  
Torsional Vibrations ◽  
Electric Motors ◽  
Operational Conditions ◽  
Asynchronous Motors ◽  
Drive Trains ◽  
Transient And Steady State

In the paper there is presented a reliable structural model of the rotating mechanical systems as well as mathematical models of the stepping, synchronous and asynchronous motors, by means of which electromechanical coupling effects can be thoroughly investigated. An importance and severity of these phenomena, not sufficiently explored till present, have been demonstrated by results obtained for transient and steady-state operational conditions in the computational examples concerning torsional vibrations of drive trains with various electric motors.

scholarly journals Misspecification in Simultaneous Systems: An Alternative Test and Its Application to a Model of the Shrimp Market

1988 ◽  
Vol 20 (2) ◽  
pp. 65-72 ◽  
Author(s):  
J. D. Lea ◽  
J. S. Shonkwiler
Keyword(s):  
Null Hypothesis ◽  
Structural Model ◽  
A Priori ◽  
Econometric Models ◽  
Specification Test ◽  
Alternative Test ◽  
Three Stage Least Squares ◽  
Simultaneous Systems ◽  
Reduced Forms ◽  
The U.S

AbstractConcern over the effects of public policies based on misspecified econometric models motivates interest in a procedure to test, diagnose, and improve the specification of models that have been estimated with three-stage least squares. A test of system-wide specification based on Hausman's specification test is employed in a test of the a priori restrictions placed on the parameters of a structural model of the U.S. shrimp market. The null hypothesis of proper specification is rejected. After diagnosis via a comparison of unrestricted and restricted reduced forms and respecification, the null hypothesis cannot be rejected.

Sound Field Distribution Research of Polymer Materials Ultrasonic Probe Chip Polymer Materials

2012 ◽  
Vol 466-467 ◽  
pp. 523-527
Author(s):  
Qi Zhang ◽  
Rong Bao Chen ◽  
Xuan Yu Li ◽  
Chang Hua Chen
Keyword(s):  
Field Distribution ◽  
High Performance ◽  
Electromechanical Coupling ◽  
Sound Field ◽  
Thickness Measurement ◽  
Polymer Materials ◽  
Coarse Grained ◽  
Electromechanical Coupling Coefficient ◽  
Materials Testing ◽  
Ultrasonic Probe

Compared to the probe based on conventional piezoelectric ceramic, the high-performance ultrasonic probe made from polymer composite materials is much better, which has characteristics such as high sensitivity, wide bandwidth and good directional. And probe’s thickness electromechanical coupling coefficient KT value is up to 68%, which means it can reduce the crosstalk effectively to the phased array probe. In industrial, due to its high bandwidth, it has obvious advantages when used in coarse-grained materials testing and high-precision thickness measurement. In the medical field, ultrasound will reflex significantly at the impurities or the interfaces, and produce the Doppler effect in the flow of blood. Based on the sound field distribution comparative study of polymer materials ultrasonic probe chip, this paper proposed some polymer new applications in ultrasonic testing field.

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