共查询到20条相似文献,搜索用时 62 毫秒
1.
Hui Li Sunil Saigal Ashraf Ali Timothy P. Pawlak 《International journal for numerical methods in engineering》1994,37(2):343-356
Numerous engineering problems, especially those in electromagnetics, often require the treatment of the unbounded continua. Mapped infinite elements have been developed for the solution of 3-D magnetic vector potential equations in infinite domain that may be used in conjunction with the standard finite elements. The electromagnetic field equations are written in terms of the magnetic vector potential for the infinite domain, and 3-D mapped infinite eiement formulation based on these equations is presented in detail. A series of magnetostatics and eddy current problems are solved to demonstrate the validity and efficiency of the procedure. These numerical results indicate that the combined finite–infinite element procedure is computationally much more economical for the solution of unbounded electromagnetic problems, especially when using the vector potential formulation, as the number of system equations decreases substantially compared to the finite element only procedure. The present procedure shows promise for the treatment of large practical industrial 3-D eddy current problems with manageable computer resources. 相似文献
2.
Rucker W.M. Magele C. Schlemmer E. Richter K.R. 《IEEE transactions on magnetics》1992,28(2):1099-1102
A boundary element formulation for 3-D nonlinear magnetostatic field problems using the total scalar potential and its normal derivative as unknowns is described. The boundary integral equation is derived from a differential equation for the total scalar potential where a nonlinear operator term can be separated from a linear term. The nonlinear term leads to a volume integral which can be treated as a known forcing function within an iterative solution process. An additional forcing term results from the magnetic excitation coil system. It is shown that the line integral of the magnetic source field which can be defined outside of the current-carrying regions as a gradient of a scalar potential acts as an excitation term. The proposed method is applied to a test problem where an iron cube immersed in the magnetic field of a cylindrical coil is investigated. The numerical results for different saturation stages are compared with finite element method (FEM) calculations. The comparison with FEM calculations shows a good agreement only in highly saturated iron parts 相似文献
3.
T. S. Saitoh M. Nakamura T. Gomi 《International journal for numerical methods in engineering》1994,37(11):1793-1805
In this paper, the time–space method (TSM) for multidimensional melting and solidification problems is proposed. In the proposed TSM, the timewise co-ordinate is incorporated into one of the spatial co-ordinates, thereby transforming the usual transient 2-D (or 3-D) problems into steady 3D (or 4-D) boundary-value problems. Since time integration is not necessary, the TSM has a feature that eliminates the so-called numerical instability which has been a great concern in the principal numerical methodologies in the past. That is, no error propagation in the timewise direction occurs in the TSM calculation. The TSM is applicable to almost all transient heat transfer and flow problems. The computer running time will be reduced to only 1/100th–1/1000th of the existing schemes for 2-D or 3-D problems. The sample calculations are presented for a 2-D melting problem in a square cavity and the validity of the present method is examined. 相似文献
4.
A meshless method based on the local Petrov–Galerkin approach is proposed for crack analysis in two-dimensional (2-D) and
three-dimensional (3-D) axisymmetric magneto-electric-elastic solids with continuously varying material properties. Axial
symmetry of geometry and boundary conditions reduces the original 3-D boundary value problem into a 2-D problem in axial cross
section. Stationary and transient dynamic problems are considered in this paper. The local weak formulation is employed on
circular subdomains where surrounding nodes randomly spread over the analyzed domain. The test functions are taken as unit
step functions in derivation of the local integral equations (LIEs). The moving least-squares (MLS) method is adopted for
the approximation of the physical quantities in the LIEs. The accuracy of the present method for computing the stress intensity
factors (SIF), electrical displacement intensity factors (EDIF) and magnetic induction intensity factors (MIIF) are discussed
by comparison with numerical solutions for homogeneous materials. 相似文献
5.
A boundary-element method using a magnetic vector potential for eddy-current analysis is described. For three-dimensional (3-D) problems, the tangential and normal components of the vector potential, tangential components of the magnetic flux density, and an electric scalar potential on conductor surfaces are chosen as unknown variables. When the approximation is introduced so that the conductivity of the conductor is very large in comparison with the conductivity of air, the number of unknowns can be reduced; also, for axisymmetric models the scalar potential can be eliminated from the unknown variables. The formulation of the boundary-element method using the vector potential, and computation results by the proposed method, are presented 相似文献
6.
Integral analysis of a magnetic field for an arbitrary geometry coil with rectangular cross section 总被引:1,自引:0,他引:1
Hong Lei Lian-Ze Wang Zi-Niu Wu 《IEEE transactions on magnetics》2002,38(6):3589-3593
The integral method can effectively analyze magnetic fields, but the traditional integral method can analyze only coils with regular geometries. Therefore, a new integral method was developed to calculate the three-dimensional (3-D) magnetic field created by an arbitrary geometry coil with a rectangular cross section using the local coordinate method and a 3-D coordinate transformation. However, when the field points are on the surface of the coil or the basic segment is the right angle trapezoidal prism, singularities occur that make the numerical analysis of the magnetic field more difficult. Thus, we present here some mathematical methods to eliminate the singularities to allow accurate numerical analysis of the magnetic field. We validate the integral method by comparing it with the analytical solutions for regular geometry coils. 相似文献
7.
Langru Li Youqin Xiang 《IEEE transactions on magnetics》1990,26(2):371-374
The basic equations of two scalar potentials and their finite-element discretized formulations are discussed. In order to compute the 3-D magnetic field in a complex solution domain, a method of hybrid elements consisting of tetrahedron, triangular prism, and arbitrary hexahedron is used, and its feasibility is justified by theoretical analysis and numerical examples. This method is successfully used to calculate the 3-D nonlinear magnetic field in a claw-pole electric machine with a power rating of 500 W 相似文献
8.
Do-Wan Kim Hyun-Kyo Jung Song-Yop Hahn Cheol-Gyun Lee 《IEEE transactions on magnetics》2000,36(6):3932-3938
Among the components of induction motors, the end ring is needed to connect rotor bars electrically. Some approaches to calculating its resistance employ equivalent circuit methods, but they are not accurate because they assume ideal sinusoidal current distribution. This paper presents a method to calculate the current distribution in the end ring by the finite-element method (FEM). This paper uses both two-dimensional (2-D) A-Φ FEM analysis and three-dimensional (3-D) T-Ω FEM analysis. The magnetic flux density is obtained from 2-D analysis, and the electric vector potential is obtained from 3-D analysis. With these results, the current distribution in the end ring is calculated and the proper size of the end ring is selected by solving some case problems 相似文献
9.
Summary In this paper, an analytical method is presented for 3-D (three-dimensional) researches of laminated composite plates. Using this method, the linear and nonlinear analytical 3-D solutions of high accuracy are obtained for circular laminated composite plates with rigidly clamped edges and under uniform transverse loading. Galerkin's method and the perturbation technique are used to obtained the solutions which satisfy the basic differential equations of linear and nonlinear 3-D problems. The geometric nonlinearity from a moderately large deflection is considered. Many numerical results of displacements and stresses are shown in figures. In the analytical method, there are not any restrictions regrading the stacking sequence of laminated composite plates, so the method may be used to analyze the 3-D problems of unsymmetrical laminated plates. 相似文献
10.
Finite element analysis of 3-D eddy currents 总被引:8,自引:0,他引:8
The authors review formulations of three-dimensional (3-D) eddy current problems in terms of various magnetic and electric potentials. The differential equations and boundary conditions are formulated to include the necessary gauging conditions and thus to ensure the uniqueness of the potentials. Different sets of potentials can be used in distinct subregions, thus facilitating an economic treatment of various types of problems. A novel technique for interfacing conducting regions with an electric vector and a magnetic scalar potential to eddy-current-free regions with a magnetic vector potential is described. Finite-element solutions to several large eddy-current problems are presented 相似文献
11.
A package named VECTOR for solving 3-D eddy current problems is presented. The package is a developmental version of the commercial package CARMEN and in the same way solves the vector diffusion equation, involving a modified vector potential, within conductors and the scalar Poisson equation, using a magnetic scalar potential, in non-eddy-current regions. It has been shown that this set of equations yields a unique solution for both the magnetic vector potential (and hence the currents) and the fields (which are derived from the magnetic potentials by differentiation). This package has recently been extended to solve transient problems, using simple time-stepping techniques. Some results using the package for problems with analytic solutions are given 相似文献
12.
13.
A Boundary Integral Formulation on Unstructured Dual Grids for Eddy-Current Analysis in Thin Shields
A 3-D boundary integral method (3-D BIM) capable of analyzing eddy currents in thin shields is presented. This novel approach is formulated in terms of loop currents in order to implicitly fulfill the div-free condition for quasi-magnetostatic problems. Using nonorthogonal dual grids unknowns are defined on nodes, resulting in a very efficient formulation with limited memory requirements. The proposed method is tested on an axisymmetric model showing a good agreement with the analytical solution. 3-D BIM is then applied to analyze a real case of low-frequency magnetic shielding 相似文献
14.
Biro O. Preis K. Renhart W. Richter K.R. Vrisk G. 《IEEE transactions on magnetics》1990,26(2):438-441
The authors describe their numerical experiences in applying FEM (finite-element method) solution techniques to a 3-D (three-dimensional) eddy-current problem with a coil-driven multiply connected conductor, the benchmark problem No.7 of the International TEAM Workshops. Several formulations have been tried using a magnetic vector and electric scalar potential or an electric vector and a magnetic scalar in the conductor and a magnetic vector or scalar potential outside. The problem has been solved at two frequencies. The authors briefly describe the formulations used and compare the performance. Magnetic field and current density plots are also compared. The advantages and disadvantages of the various versions are pointed out. The use of a magnetic scalar potential H rather than a magnetic vector potential A outside the conductor and the hole substantially reduces the number of degrees of freedom and thus the computational effort. The versions using it in the conductor yield relatively ill-conditioned systems. Also, at the higher frequency, the conditioning deteriorates considerably 相似文献
15.
In this paper, an iterative boundary element method (IBEM) for both 2-D and 3-D cavitating hydrofoils moving steadily inside a numerical wave tank (NWT) is presented and some extensive numerical results are given. The cavitating hydrofoil part, the free surface part and the wall parts of NWT are solved separately, with the effects of one on the others being accounted for in an iterative manner. The cavitating hydrofoil surface, the free surface, the bottom surface and the side walls are modelled by a low-order potential based panel method using constant strength dipole and source panels. Second-order correction on the free surface in 2-D are included into the calculations by the method of small perturbation expansion both for potential and for wave elevation. The source strengths on the free surface are expressed in terms of perturbation potential by applying first-order (linearized) and second-order free surface conditions. The IBEM is applied to a 2-D (NACA16006 and NACA0012) and a 3-D rectangular cavitating hydrofoil and the effect of number of iterations, the effect of the depth of the hydrofoil from finite bottom and the effect of the walls of NWT, on the results are discussed. 相似文献
16.
L. R. Dupr R. Van Keer J. A. A. Melkebeek 《International journal for numerical methods in engineering》1998,42(6):1005-1023
The main purpose of this paper is to incorporate a refined hysteresis model, viz., a vector Preisach model, in 2-D magnetic field computations. Two complementary formulations, based either on the scalar or on the vector potential, are considered. The governing Maxwell equations are rewritten in a suitable way, that allows to take into account the proper magnetic material parameters and, moreover, to pass to a variational formulation. The variational problems are solved numerically by a Finite Element approximation, using a quadratic mesh, followed by a time discretization method based upon a modified Cranck–Nicholson algorithm. Finally, the effectiveness of the presented mathematical tools have been confirmed by several numerical experiments, comparing the complementarity of the two procedures. © 1998 John Wiley & Sons, Ltd. 相似文献
17.
YU XIE MUKHERJEE SUBRATA MUKHERJEE 《International journal for numerical methods in engineering》1997,40(5):797-815
The Element-Free Galerkin (EFG) method allows one to use a nodal data structure (usually with an underlying cell structure) within the domain of a body of arbitrary shape. The usual EFG combines Moving Least-Squares (MLS) interpolants with a variational principle (weak form) and has been used to solve two-dimensional (2-D) boundary value problems in mechanics such as in potential theory, elasticity and fracture. This paper proposes a combination of MLS interpolants with Boundary Integral Equations (BIE) in order to retain both the meshless attribute of the former and the dimensionality advantage of the latter! This new method, called the Boundary Node Method (BNM), only requires a nodal data structure on the bounding surface of a body whose dimension is one less than that of the domain itself. An underlying cell structure is again used for numerical integration. In principle, the BNM, for 3-D problems, should be extremely powerful since one would only need to put nodes (points) on the surface of a solid model for an object. Numerical results are presented in this paper for the solution of Laplace's equation in 2-D. Dirichlet, Neumann and mixed problems have been solved, some on bodies with piecewise straight and others with curved boundaries. Results from these numerical examples are extremely encouraging. © 1997 by John Wiley & Sons, Ltd. 相似文献
18.
Computation of the Three-Dimensional Magnetic Field From Solid Permanent-Magnet Bipolar Cylinders By Employing Toroidal Harmonics 总被引:1,自引:0,他引:1
We present an analytical method, employing toroidal harmonics, for computing the three-dimensional (3-D) magnetic field from a circular cylindrical bipolar permanent magnet. Bipolar magnets are those which are polarized perpendicular to the axis of the cylinder. We take a completely analytical approach in order to facilitate parametric studies of the external 3-D magnetic field produced by bipolar magnets. The results of our analysis are verified by comparing them to previously published results. The application of toroidal harmonics are ultimately shown to be well-suited for both parametric studies as well as numerical computation. 相似文献
19.
《IEEE transactions on magnetics》2009,45(4):1990-1998
20.
Finite element scheme for transient 3D eddy currents 总被引:1,自引:0,他引:1
A transient 3-D finite-element model is presented. The method is based on the solution of the magnetic scalar potential in nonconducting regions and the magnetic vector potential and an electric scalar potential in eddy-current regions. Multiply connected regions of magnetic scalar can be avoided by extending the region modeled by the magnetic vector potential to fill any holes in the conducting regions. The model was used to simulate the FELIX brick experiment 相似文献