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Inductance calculations for coaxial iron-core coils shielded by cylindrical screens of high permeability

IET ELECTRIC POWER APPLICATIONS 2019年第6期13卷 802-811页

作者： Zhu, Yuanzhe Chen, Baichao Luo, Yao Zhu, Runhang Wuhan Univ Sch Elect Engn & Automat Wuhan Hubei Peoples R China

Coaxial iron-core coil system shielded by a magnetic screen is a complex model for analytical calculation, because a complicated boundary value problem must be tackled for obtaining inductances of the coils in this situation. Truncated region eigenfunction expansion method is a suitable way to work out such a problem containing complex boundary conditions. Three different models are taken into consideration in this study. Starting with coil system shielded by two infinitely large plates, the basic steps of the proposed method are introduced carefully. Then the relevant techniques and conclusions are applied to the iron-core coils shielded by a fully enclosed cylindrical screen of high permeability and a lidless one. The effectiveness of the proposed method is verified by comparing with finite element method software and experiments. From relevant data, it is evident that the proposed method is much faster and can be easily used for forecast and evaluation of new schemes in device design process.

关键词： finite element analysis eigenvalues and eigenfunctions boundary-value problems coils complex boundary conditions relevant techniques fully enclosed cylindrical screen high permeability finite element method software inductance calculations coaxial iron-core coils cylindrical screens coaxial iron-core coil system magnetic screen complex model analytical calculation complicated boundary value problem truncated region eigenfunction expansion method

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A dielectric frequency response model to evaluate the moisture content within an oil impregnated paper condenser bushing

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IET SCIENCE MEASUREMENT & TECHNOLOGY 2013年第4期7卷 223-231页

作者： Smith, David J. McMeekin, Scott G. Stewart, Brian G. Wallace, Peter A. Glasgow Caledonian Univ Sch Engn & Built Environm Glasgow G4 0BA Lanark Scotland

Increased moisture content within an oil-paper insulation system can significantly reduce its life expectancy, and for oil impregnated paper condenser type bushings, it is the most common cause of failure. Distinction between moisture contents using traditional power frequency tests of dissipation factor and capacitance can be difficult, particularly at ambient temperatures. Dielectric frequency response is becoming an established technique to measure the dissipation factor and capacitance of a bushing, but to date an accurate model to evaluate the condenser moisture content has not been presented using this technique. In this study, a dielectric frequency response bushing model is proposed and finite element method software is used to simulate the variation in dissipation factor and capacitance of a bushing with varying moisture content, as a function of frequency and temperature. The modelled results are compared with measurements reported in the literature and from the authors' own field measurements, where a good agreement is demonstrated. It is shown that the distinction in dissipation factor between moisture contents at frequencies <0.1 Hz is in excess of ten times greater than at 50 Hz. The proposed model can be used by practitioners to evaluate moisture content within the condenser insulation and distinguish between moisture contents ranging from 0.2 to 4.0%.

关键词： Dielectric materials and properties life expectancy reduction power transformer insulation finite element analysis Computerised instrumentation Transformers and reactors Humidity measurement dielectric frequency response model Organic insulation moisture measurement Impedance and admittance measurement condenser moisture content evaluation dissipation factor measurement impregnated insulation computerised instrumentation condenser insulation Power line supports, insulators and connectors frequency response paper bushings finite element method software condensers (steam plant) oil-paper insulation system oil impregnated paper condenser bushing life testing capacitance measurement insulating oils finite element analysis

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Inductance calculations for non-coaxial Bitter coils with rectangular cross-section using inverse Mellin transform

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IET ELECTRIC POWER APPLICATIONS 2019年第1期13卷 119-125页

作者： Yu, Yue Luo, Yao Tsinghua Univ Dept Elect Engn Beijing Peoples R China Wuhan Univ Sch Elect Engn & Automat Wuhan Hubei Peoples R China

Recently, the mutual inductance between Bitter coils with rectangular cross-section has been calculated through Bessel function approach or figured out with analytical and semi-analytical formulas. In this study, using the inverse Mellin transform, relevant Bessel integrals will be continued analytically to the complex plane, and then by virtue of contour deformation and residue theorem, they can be expanded to the series containing the hypergeometric functions. In addition, the results obtained by this method are compared with those by finite element method software. Also, the presented approach shows great advantages of high accuracy and very short computational time.

关键词： electrical engineering computing finite element method software noncoaxial Bitter coils finite element analysis Electrical engineering computing Integral transforms inductance calculations Superconducting coils and magnets Bessel functions rectangular cross-section Bessel function inverse transforms inductance superconducting coils hypergeometric functions integration inverse Mellin transform Mathematical analysis mathematical operators finite element analysis Bessel integrals

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Leakage current analysis of polymeric insulators under uniform and non-uniform pollution conditions

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IET GENERATION TRANSMISSION & DISTRIBUTION 2017年第11期11卷 2947-2957页

作者： Ahmadi-Joneidi, Iman Shayegani-Akmal, Amir Abbas Mohseni, Hossein Univ Tehran Dept High Voltage Lab North Kargar Ave IR-14395 Tehran Iran

This study presents two different methods under uniform and non-uniform pollution layer in order to measure and calculate the leakage current (LC) of silicone rubber insulators. Experimental test for evaluating the LC analysis of polluted insulator have been done in a laboratory clean fog chamber. The electric field and potential distributions were obtained from finite element method software for 3D models. The mathematical background and circuit theory are described in details by a section of insulator and using the extended form factor formula. The surface conductivity used in the calculations was extracted from the measured LC after wetting rate. LC characteristics under 1:1, 1:2, 1:5 and 1:10 ratios of top to bottom surface salt deposit density on polymeric insulators are studied. To verify the proposed models of this study, the results of experimental data and two other approaches are compared with together before dry-band formation. Moreover, a dynamic LC model under uniform pollution layer has been introduced and extended in order to calculate the LC when the formation of dry-bands along the insulator surface occurs. The dynamic model is drawn from experimental data and measured surface conductivity.

关键词： insulator contamination leakage currents silicone rubber insulators fog electric fields finite element analysis surface conductivity wetting polymer insulators polymeric insulator leakage current analysis uniform pollution conditions nonuniform pollution conditions silicone rubber insulators polluted insulator LC analysis laboratory clean fog chamber electric field potential distributions finite element method software 3D models circuit theory extended form factor formula surface conductivity wetting rate bottom surface salt deposit density dry-band formation dynamic LC model

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Dynamic Mechanical Behaviour of Innovative Structures Incorporating Cork

Dynamic Mechanical Behaviour of Innovative Structures Incorp...

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13th Conference of the Sociedade-Portuguesa-de-Materiais/4th International Materials Symposium

作者： Gameiro, C. P. Cirne, J. Univ Coimbra Dept Mech Engn CEMUC P-3030788 Coimbra Portugal

ISBN: (纸本)9780878493739

Cork is a natural cellular material which has been used for centuries, in natural and agglomerate forms, mainly for applications related to the wine, the automotive and the construction industries. It is a very durable and ecological material, used for thermal, acoustic and vibrating insulation as well as packaging, among others. This paper highlights some of the aspects of a topic of great interest, not much explored yet, which consists of the study of the dynamic mechanical behaviour of innovative structures incorporating cork, dedicated to energy-absorption. Experimental and numerical tests, using the finite element method software LS-DYNA(TM), were performed in order to evaluate the effects of filling agglomerate cork inside thin-walled metallic tubes, with variable geometries and thicknesses, impacted uniaxially at quasi-static and high strain rates. Sonic relevant comparisons were carried out and the results obtained allowed concluding that cork might be a viable energy-absorbing material for application in some metallic structures subjected to impact loadings.

关键词： Cork Impact Metallic Tubes Energy-Absorption Experimental finite element method software

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The Coupled-Channel method for Modelling Quantum Transmission of Composite Systems 19th

The Coupled-Channel Method for Modelling Quantum Transmissio...

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19th International Conference on Distributed Computer and Communication Networks (DCCN)

作者： Vinitsky, S. I. Gusev, A. A. Chuluunbaatar, O. Gozdz, A. Derbov, V. L. Joint Inst Nucl Res Dubna Russia RUDN Univ Peoples Friendship Univ Russia 6 Miklukho Maklaya St Moscow 117198 Russia Univ Maria Curie Sklodowska Inst Phys Lublin Poland Saratov NG Chernyshevskii State Univ Saratov Russia Natl Univ Mongolia Inst Math Univ St Ulaanbaatar Mongolia

ISBN: (纸本)9783319519173;9783319519166

The description of quantum transmission of composite systems of barriers or wells using the coupled-channel method is presented. In this approach the multichannel scattering problem for the Schrodinger equation is reduced to a set of coupled second-order ordinary differential equations with the boundary conditions of the third type and solved using the finite element method. The efficiency of the proposed approach is demonstrated by the example of analyzing metastable states that appear in composite quantum systems tunnelling through barriers and wells and give rise to the quantum transparency and total reflection effects.

关键词： Coupled-channel method Quantum tunnelling Second-order ordinary differential equations finite element method software

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Numerical implementation of an impedance boundary condition considering a finite boundary layer

Numerical implementation of an impedance boundary condition ...

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AIAA Aviation Forum and Exposition

作者： Seki, Leonardo A. Spillere, Andre M. N. Cordioli, Julio A. Univ Fed Santa Catarina BR-88040900 Florianopolis SC Brazil

ISBN: (数字)9781624106101

ISBN: (纸本)9781624106101

The so-called Ingard-Myers boundary condition is commonly used to represent an acoustic impedance in the presence of flow. However, recent studies have shown that may be inadequate in different conditions. Its main problem has been identified as the assumption of a boundary layer of infinitesimal thickness, and several alternative boundary conditions that address this shortcoming have been proposed. In general, the new boundary conditions performed better than the widely used Ingard-Myers condition, but these studies are somewhat limited to simpler geometries. The final goal of the work is to evaluate the impact of a finite boundary layer on the attenuation provided by acoustic liners in turbofan engines. The procedure to obtain an adequate finite element formulation of the chosen boundary condition is described. The implementation is validated by comparison with a simple circular duct analytical model, and used to predict liner attenuation on a realistic turbofan engine geometry and operating conditions, and on a scaled-down fan rig.

关键词： Boundary Layer Thickness finite element Formulation Acoustic Propagation Turbofan Engines Numerical Modeling Blade Passing Frequency finite element method software Sound Pressure Level Irrotational Flow Velocity Profiles

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A Meta Model for Systems Engineering

A Meta Model for Systems Engineering

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Livingston, John W. Riverside Res Beavercreek OH 45431 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

This paper outlines the requirements and architecture of software suitable for supporting the development of a systems or system of systems by groups of distributed teams and stakeholders. A meta model is developed to guide such a development. This paper discusses the wide range of functionality needed. Team command and control structures are needed. Performance, Effectiveness, Risk Cost and Schedule (PERCS) needs are outlined. Complex system models need to be easily created navigated and modified. The ability to produce high quality CAD geometry is generally needed. Parametric models need to be built up quickly using pre-engineered parametric components driven by familiar engineering parameters. A library of pre-engineered parametric components is needed. The component library must be extensible by the user if different components are needed. Sensitivity analysis, uncertainty quantification and propagation are needed to support risk analysis. Unified model data storage and retrieval and automatic report generation are needed for a range different stakeholder.

关键词： Model Based System Engineering Sensitivity Analysis Data Storage Feedback Loop Graphical User Interface Surrogate Model Design for Manufacturing Space Exploration Computational Fluid Dynamics Code finite element method software

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Classical, Refined, and Component-Wise Analysis of Reinforced-Shell Wing Structures

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AIAA JOURNAL 2013年第5期51卷 1255-1268页

作者： Carrera, E. Pagani, A. Petrolo, M. Politecn Torino Dept Mech & Aerosp Engn I-10129 Turin Italy

This paper compares early and very recent approaches to the static analysis of reinforced-shell wing structures. Early approaches were those based on the pure semimonocoque theory along with the beam assumptions of the Euler Bernoulli and Timoshenko type. The recent approaches are based on a hierarchical, one-dimensional formulation. These are obtained by adopting various polynomial expansions of the displacement field above the cross-section of the structure according to the unified formulation which was recently proposed by the first author. Two classes were developed in the unified formulation framework. In the first class, Taylor expansion models were developed by exploiting N-order Taylor-like polynomials;classical beam theories (Euler-Bernoulli and Timoshenko) were obtained as special cases of Taylor expansion. In the second class, Lagrange expansion models were built by means of four- and nine-point Lagrange-type polynomials over the cross-section of the wing. The component-wise approach was obtained by using different four- and nine-point Langrangian descriptions for different wing components including panels, ribs, spar caps, stringers, and transverse ribs. The finite element method was used to develop numerical applications in the weak form. finite element matrices and vectors are expressed in terms of fundamental nuclei whose forms do not formally depend on the order and the expansion. A number of typical aeronautical structures were analyzed, and semimonocoque results were compared to classical (Euler-Bernoulli and Timoshenko), refined (Taylor expansion), and component-wise (Lagrange expansion) models. Stress and displacement fields of simple statically determinate, redundant, and open-section wing-box structures were analyzed. finite element models by a commercial software that make use of solid and shell elements were used for comparison purposes. Results have highlighted the enhanced capabilities of the present refined and component-wise formulations.

关键词： Aircraft Structures finite element Formulation Euler Bernoulli Beam Theory Poisson's Ratio Wing Box Structure finite element method software Stress Distribution Rectangular Wing Mathematical Models Computer Aided Design

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Vibration and Buckling Analysis of Curvilinearly Stiffened Plates Using finite element method

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AIAA JOURNAL 2015年第5期53卷 1319-1335页

作者： Shi, Peng Kapania, Rakesh K. Dong, C. Y. Beijing Inst Technol Sch Aerosp Engn Beijing 100081 Peoples R China Virginia Polytech Inst & State Univ Dept Aerosp & Ocean Engn Blacksburg VA 24060 USA

A finite element method based approach is developed for studying the static, vibration, and buckling behaviors of curvilinearly stiffened plates in the presence of in-plane compressive and tensile stresses. The first-order shear deformation theory is employed for both the plate and the Timoshenko beam modeling. Interpolation functions are used to build the displacement mapping between the stiffener and the plate nodes to allow the stiffener to be placed anywhere within the plate. One of the advantages of the present method is that the plate need not be remeshed while the stiffener configuration is changed;another advantage is that the results obtained by the present method with a much fewer number of elements match well with the results obtained by using a commercial finite element method software. Several numerical examples are solved to study both the static and dynamic behaviors of stiffened plates. The effects of boundary conditions, stiffener eccentricity, stiffener curvature, stiffener-plate geometry parameters, inplane load condition, stiffener-plate cross-section area ratio, and stiffness ratio on the static and dynamic behaviors of a curvilinearly stiffened plate are investigated. Results have shown that the behavior of the natural frequency parameter as a function of applied in-plane stress could be affected by the plate thickness, in-plane load condition, stiffener-plate cross-section area ratio, and stiffness ratio during compression only, but not when subjected to in-plane tension.

关键词： finite element Modeling Buckling Analysis finite element method software Tensile Stress Shear Deformation Free Vibrations Timoshenko Beam Theory Kinetic Energy Curved Beam Plate Theory

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