Electric Fields in Composite Dielectrics and their Applications

This paper proposes a 3D finite element method procedure to study the electrostrictive property of the single-walled carbon nanotube (SWCNT)-based composite. The numerical model in nanoscale is developed to investigate the electrostrictive behavior of the SWCNT and the polyvinylidene fluoride and trifluoroethylene P(VDF-TrFE) composite. A bond electrical contact model is adopted to reproduce the coupled electromechanical effects of the interface between SWCNT and P(VDP-TrFE). According to the model proposed, the mechanism of the enhanced electrostriction in SWCNT/P(VDP-TrFE) composite is intuitively demonstrated. Numerical results show that aside from the variation of electric field, the electrostriction of the SWCNT/P(VDP-TrFE) composite is greatly depend on the volume fraction of SWCNT and the difference of dielectric constant between SWCNT and P(VDP-TrFE) copolymer. While the dielectric constant of SWCNT is mainly depend on the chirality of SWCNT, which means that the electrostriction of the SWCNT/P (VDP-TrFE) composite is also largely depend on the chirality of SWCNT.

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“…According to the Laplace's equation for the electric potential (£), the governing equation for £ in each media is [17]:…”

Section: Finite Element Model Of Swcnt/p(vdf-trfe) Compositementioning

confidence: 99%

Electrostriction study for single-walled carbon nanotubes-based composite

Tang

Hami

2014

Advanced Composite Materials

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“…Generally two approaches are used to derive the BIE: one is the surface integral equation approach (SIEA) and the other one is the volume integral equation approach (VIEA) [3]. The existing BIEs have been reviewed in the reference [4].…”

Section: Introductionmentioning

confidence: 99%

“…As the boundary conditions are fully satisfied, the BIEs for the electrostatic analysis are derived. This approach is known as the Boundary Element Method (BEM) and is conventionally employed to solve electrostatic problems [2,4].…”

Section: Introductionmentioning

confidence: 99%

“…From the potential � P due to � s , we derive a BIE for the electrostatic analysis. The approach using the BIE with � s as unknown is usually called 'Surface Charge Method (SCM)' and employed as well as the BEM [4,5]. Further, P is related to the double layer charge � d , which is equivalent to loop magnetic currents K l on the airmaterial interface [6].…”

Section: Introductionmentioning

confidence: 99%

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Electrostatic Analysis by Boundary Integral Equation with Loop Current and Surface Charge as Unknowns

Andjelic

Ishibashi

2013

Journal of the Japan Society of Applied Electromagnetics and Me

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In the electrostatic analysis, we usually treat the effect of polarization charges on dielectric surface and true charges on conductor surface. When we solve problems with high permittivity using the surface charge method, we cannot get accurate solutions due to cancellation errors. In this paper we propose a novel approach to solve the problems with high permittivity. The boundary integral equation in the proposed method is derived by replacing the polarization charges by loop currents instead of surface charges used in the surface charge method. The proposed method is effectively applicable because it contains only one unknown. Besides, even though the loop current gives originally scalar potentials, Biot-Savart law gives directly the electric flux density. Finally, we have compared the proposed method and surface charge method by solving some typical examples.

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“…On the other hand, due to the use of solid insulators, surface discharge may occur where solid insulators, electrodes and insulation gases touch the boundary (i.e., triple junction) [6]. It is known that surface dielectric strength is reduced near this triple junction [7]. Therefore, the surface discharge at the triple junction is important in the design of electric power devices.…”

Section: Introductionmentioning

confidence: 99%

Surface Discharge Characteristics Study on the Laminated Solid Insulator in Quasi-Uniform Electric Field with Dry Air

Min¹,

Bae²,

Kang³

et al. 2015

Journal of Electrical Engineering and Technology

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-Dry air is an excellent alternative to SF 6 gas and is used as an insulation gas in Ecofriendly Gas Insulated Switchgears (EGISs), which has gained popularity in industry. Solid insulators in EGIS play an important role in electrical insulation. On the other hand, surface discharge can occur easily when solid insulators are used. This paper explored the surface discharge characteristics on the structure of three-layered laminated solid insulators to elevate the flashover voltage. A laminated solid insulator was inserted after the quasi-uniform electric field was formed in the test chamber. Dry air was then injected to set the internal pressure to 1 ~ 6 atm, and the AC voltage was applied. When identical solid insulators were stacked, the surface discharge characteristics were similar to those of a single solid insulator. On the other hand, the flashover voltage rose when the middle part was thicker and had lower permittivity than the top and bottom parts in the laminated solid insulator. Based on experimental results, when stacking a solid insulator in three layers, the middle part of the solid insulator should be at least four times as thick as the top and bottom parts and have lower permittivity than the others. In addition, the flashover voltage increased with increasing gas pressure on the surface of the laminated solid insulator due to the gas effect. This study may allow insulation design engineers to have useful information when using dry air for the insulation gas where the surface discharge can occur.

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Electric Fields in Composite Dielectrics and their Applications

Cited by 32 publications

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Electrostriction study for single-walled carbon nanotubes-based composite

Electrostriction study for single-walled carbon nanotubes-based composite

Electrostatic Analysis by Boundary Integral Equation with Loop Current and Surface Charge as Unknowns

Surface Discharge Characteristics Study on the Laminated Solid Insulator in Quasi-Uniform Electric Field with Dry Air

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