scholarly journals Rubber Surface Change and Static Charging under Periodic Stress

2018 ◽  
Vol 2 (4) ◽  
pp. 55 ◽  
Author(s):  
Leandra Santos ◽  
Yan Campo ◽  
Douglas da Silva ◽  
Thiago Burgo ◽  
Fernando Galembeck
Keyword(s):  
Electric Field ◽  
Smart Materials ◽  
Complex Surface ◽  
Elastic Base ◽  
Linear Deformation ◽  
Rubber Surface ◽  
Dependent Potential ◽  
Symmetric Effect ◽  
Periodic Stress ◽  
Adsorptive Properties

Rubber materials play an important role in robotics, due to their sensing and actuating abilities, that are exploited in soft smart materials endowed with shape-adaptive and electroadhesive properties. The application of an electric field produces non-linear deformation that has been extensively modelled, but is not understood at the molecular level. The symmetric effect (the production of an electric field due to rubber deformation) was recently discovered and explained as follows: rubber surface chemical composition and adsorptive properties change during rubber deformation, allowing the surface to exchange charge with the atmosphere. The present work describes the complex surface morphology and microchemistry of tubing made from vulcanized natural rubber, showing that it is rough and made from two domain types: stiffer elevations containing Br or Al (depending on the sample used) and O, that rise above an elastic base that is exempt of elements other than C and H. The surface area fraction occupied by the elastic base is higher in the strained rubber than when it is relaxed. Electrostatic potential on rubber surfaces was measured as a function of the stretching frequency, using Kelvin electrodes and showing frequency-dependent potential variation. This is explained considering charge exchange between the atmosphere and rubber surface, mediated by water vapor adsorbed in the stretched rubber and trapped when it relaxes.

scholarly journals Electro-responsive polyelectrolyte-coated surfaces

2017 ◽  
Vol 199 ◽  
pp. 335-347 ◽  
Author(s):  
V. Sénéchal ◽  
H. Saadaoui ◽  
J. Rodriguez-Hernandez ◽  
C. Drummond
Keyword(s):  
Electric Field ◽  
Smart Materials ◽  
Electrical Stimulus ◽  
Colloidal Dispersions ◽  
Polymer Chains ◽  
Molecular Response ◽  
Coated Surfaces ◽  
The Stability ◽  
Induced Changes ◽  
Applied Fields

The anchoring of polymer chains at solid surfaces is an efficient way to modify interfacial properties like the stability and rheology of colloidal dispersions, lubrication and biocompatibility. Polyelectrolytes are good candidates for the building of smart materials, as the polyion chain conformation can often be tuned by manipulation of different physico-chemical variables. However, achieving efficient and reversible control of this process represents an important technological challenge. In this regard, the application of an external electrical stimulus on polyelectrolytes seems to be a convenient control strategy, for several reasons. First, it is relatively easy to apply an electric field to the material with adequate spatiotemporal control. In addition, in contrast to chemically induced changes, the molecular response to a changing electric field occurs relatively quickly. If the system is properly designed, this response can then be used to control the magnitude of surface properties. In this work we discuss the effect of an external electric field on the adhesion and lubrication properties of several polyelectrolyte-coated surfaces. The influence of the applied field is investigated at different pH and salt conditions, as the polyelectrolyte conformation is sensitive to these variables. We show that it is possible to fine tune friction and adhesion using relatively low applied fields.

The time-dependent electric current from a flame

1984 ◽  
Vol 393 (1805) ◽  
pp. 297-308 ◽  
Keyword(s):  
Differential Equation ◽  
Electric Field ◽  
Electric Current ◽  
Diffusion Flame ◽  
Time Dependent ◽  
Two Dimensional ◽  
Ionization Detector ◽  
Flame Ionization ◽  
Dependent Potential ◽  
Ionization Detectors

An earlier static treatment of the electric current from the diffusion flame in a flame ionization detector has been extended to include time-dependent currents. The nonlinear differential equation describing the electric field in the space outside the flame has been solved analytically for a class of problems in which a time-dependent potential difference is switched on after a static current has been established. Both one- and two-dimensional geometrical configurations are considered. The results could be useful in suggesting new experiments on flame ionization detectors.

Numerical simulation of hybrid composite shape-memory alloy wire-embedded structures

2011 ◽  
Vol 22 (17) ◽  
pp. 1941-1948 ◽  
Author(s):  
Junghyun Ryu ◽  
Beom-Seok Jung ◽  
Min-Saeng Kim ◽  
JungPyo Kong ◽  
MaengHyo Cho ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Shape Memory ◽  
Smart Materials ◽  
Hybrid Composite ◽  
Hybrid Composites ◽  
Deformation Behaviour ◽  
Simulation Method ◽  
Linear Deformation ◽  
Reinforced Plastics ◽  
The Matrix

The large recovery force and non-linear deformation behaviour resulting from a change in the temperature in shape-memory alloys (SMAs) make them attractive materials for applications in smart materials and structures, as well as actuators. However, SMAs are limited in their application because they cannot support general loads such as bending or compression. SMA wire-embedded composite materials, where materials such as glass fibre reinforced plastics (GFRPs) are combined with SMAs, are proposed to overcome these limitations. However, the increased stiffness of GFRPs limits the deformation that can be achieved. The inclusion of more compliant materials, such as silicon rubber, into the matrix can improve the achievable deformation, and the characteristics of the resulting hybrid composite can be controlled by varying the conformation of the material. In this study, a numerical simulation method was developed to predict the deformation behaviour of SMA wire-embedded hybrid composites. To verify the simulation procedure, several conformations of SMA wire-embedded hybrid composites were fabricated, and their deformation behaviours were compared with the simulation results. The simulation was then used to achieve a favourable trade-off between the stiffness and the achievable deformation of the structure.

Tailoring and Characterization of the Liquid Crystalline Structure of Cellulose Nanocrystals for Opto-Electro-Mechanical Multifunctional Applications

2018 ◽  
Author(s):  
Inseok Chae ◽  
Amira Meddeb ◽  
Zoubeida Ounaies ◽  
Seong H. Kim
Keyword(s):  
Mechanical Properties ◽  
Electric Field ◽  
Smart Materials ◽  
Self Assembly ◽  
Liquid Crystalline ◽  
Functional Materials ◽  
Mechanical Force ◽  
Sum Frequency ◽  
Optical Process

Liquid crystalline (LC) behaviors of cellulose nanocrystal (CNC), derived from wood, cotton or other cellulose-based biopolymers, have been actively investigated due to their unique optical properties and their superb mechanical properties, which open up potential applications in bioelectronics and biomedical engineering. In particular, many attempts have been made to control phase and orientation of LC-CNCs because they are critical factors deciding optical and mechanical properties, and electromechanical performances. Through the applications of mechanical force, electric field and magnetic field, some degree of success has been achieved; however, realizing homogeneous arrangements of CNCs that can be exploited at the macroscale is still elusive, owing to a variety of intermolecular interactions. The characterizations of the LC phase and orientation of CNCs are also challenging due to their complex biological structures. In this report, we introduce approaches to control the phase and orientation of LC-CNCs through the self-assembly, mechanical force and electric field. The liquid crystalline behaviors of CNCs in polar solvents and at the air/water interface are discussed. Translational and rotational behaviors of CNCs under DC electric field are also investigated as a function of their surface charge and dipole moment. In addition, we introduce a nonlinear optical process, namely, sum frequency generation (SFG) spectroscopy, for the structural characterization of LC-CNCs. Using SFG, we can analyze not only crystal phase and structure, but also polar ordering of CNCs which plays a key role in determining their electromechanical performances. Development of cellulose-based smart materials will expand the spectrum of available functional materials that are lightweight, flexible, mechanically tough, and thermally stable at moderately high temperatures (up to 300°C).

scholarly journals Envelope solitons at a plasma–vacuum interface

2008 ◽  
Vol 74 (2) ◽  
pp. 151-154 ◽  
Author(s):  
P. K. SHUKLA ◽  
L. STENFLO
Keyword(s):  
Surface Wave ◽  
Electric Field ◽  
Plasma Wave ◽  
Complex Surface ◽  
Surface Plasma ◽  
Envelope Soliton ◽  
Envelope Solitons ◽  
Vacuum Interface ◽  
Nonlinear Surface

AbstractIt is shown that a nonlinear surface plasma wave at a plasma–vacuum interface can propagate in the form of a dark/grey envelope soliton. The latter is associated with a subsonic density cavity, which traps the complex surface wave electric field.

Investigation of a VLF airborne resistivity survey conducted in northern Maine

Geophysics ◽  
1978 ◽  
Vol 43 (7) ◽  
pp. 1399-1417 ◽  
Author(s):  
Steven A. Arcone
Keyword(s):  
Electric Field ◽  
Vertical Component ◽  
Complex Surface ◽  
Antenna System ◽  
Relative Strength ◽  
Mountainous Area ◽  
Topographic Effects ◽  
Flight Altitude ◽  
Rock Types ◽  
The Individual

Airborne wavetilt resistivity surveys and profiles at VLF have been analyzed for the effects of topography, altitude, and wavetilt phase and amplitude. Topographic relief is known to affect at least one electric field component, flight altitude often varies over relief, and phase, upon which the airborne measurement depends and which cannot be separated from amplitude by an airborne antenna system, depends on the earth’s resistivity stratification and the relative strength of displacement to conduction current. A mountainous area in northern Maine of predominantly slate, but containing an igneous stock, was surveyed at 150 m mean flight altitude. The 150-m survey was repeated at 300 m, and two of the 150-m flight lines were repeated at a total of three other altitudes. A comparison of the 150-m survey with the topography and with the 300-m survey revealed that although most of the resistivity information of the 150-m survey was retained at 300 m, serious differences arose due to topographic influences. Profiles of the individual electric field components at the various altitudes then revealed that topography was distorting resistivity values through its effect upon only the vertical component of the electric field. The separate influences of phase and amplitude were analyzed using the results of a ground survey of the total, complex surface impedance. The phase of the tilt proved to be important in the airborne differentiation of the rock types. The entire 150-m survey was reevaluated with topographic effects removed from the vertical electric field. The resolution of the igneous geology improved and several of these improvements were verified by the ground measurements. In addition, it is concluded from a comparison of the 300-m survey with both the topographically corrected and uncorrected 150-m surveys that wavetilt is not preserved with altitude over ground resistivity anomalies.

The symmetry group of the quantum harmonic oscillator in an electric field

Open Physics ◽  
2008 ◽  
Vol 6 (3) ◽  
Author(s):  
Juan Lejarreta ◽  
Jose Cerveró
Keyword(s):  
Schrödinger Equation ◽  
Electric Field ◽  
Harmonic Oscillator ◽  
Schrodinger Equation ◽  
Group Structure ◽  
Time Dependent ◽  
Frequency Function ◽  
General Group ◽  
Dependent Potential ◽  
The Relationship

AbstractIn this paper we present two results. First, we derive the most general group of infinitesimal transformations for the Schrödinger Equation of the general time-dependent Harmonic Oscillator in an electric field. The infinitesimal generators and the commutation rules of this group are presented and the group structure is identified. From here it is easy to construct a set of unitary operators that transform the general Hamiltonian to a much simpler form. The relationship between squeezing and dynamical symmetries is also stressed. The second result concerns the application of these group transformations to obtain solutions of the Schrödinger equation in a time-dependent potential. These solutions are believed to be useful for describing particles confined in boxes with moving boundaries. The motion of the walls is indeed governed by the time-dependent frequency function. The applications of these results to non-rigid quantum dots and tunnelling through fluctuating barriers is also discussed, both in the presence and in the absence of a time-dependent electric field. The differences and similarities between both cases are pointed out.

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