• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.7
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• pp.276-282
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• 1985

This study is concerned with the analysis of two-dimensional steady magnetic fields by the coupling of FEM and BEM. FEM(Finite Element Method)is most widely used as a method of numerical analysis and BEM (Boundary Element Method)is a newest method for it. And the results from this coupling method are compared and discussed with those of FEM only. Consequently, it is shown that to obtain the same accuracy of results the coupling method requires less calculating time and dimension than the FEM.

• Structural Engineering and Mechanics
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• v.67 no.4
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• pp.317-326
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• 2018

The iterative decomposition coupling formulation of the precise integration finite element method (FEM) and the time domain boundary element method (TD-BEM) is presented for elstodynamic problems. In the formulation, the FEM node and the BEM node are not required to be coincident on the common interface between FEM and BEM sub-domains, therefore, the FEM and BEM are independently discretized. The force and displacement converting matrices are used to transfer data between FEM and BEM nodes on the common interface between the FEM and BEM sub-domains, to renew the nodal variables in the process of the iterations for the un-coincident FEM node and BEM node. The iterative coupling formulation for elastodynamics in current paper is of high modeling accuracy, due to the semi-analytical solution incorporated in the precise integration finite element method. The decomposition coupling formulation for elastodynamics is verified by examples of a cantilever bar under a Heaviside-type force and a harmonic load.

• Coupled systems mechanics
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• v.4 no.3
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• pp.263-277
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• 2015

This paper presents a coupled FEM-BEM strategy for the numerical analysis of elastodynamic problems where infinite-domain models and complex heterogeneous media are involved, rendering a configuration in which neither the Finite Element Method (FEM) nor the Boundary Element Method (BEM) is most appropriate for the numerical analysis. In this case, the coupling of these methodologies is recommended, allowing exploring their respective advantages. Here, frequency domain analyses are focused and an iterative FEM-BEM coupling technique is considered. In this iterative coupling, each sub-domain of the model is solved separately, and the variables at the common interfaces are iteratively updated, until convergence is achieved. A relaxation parameter is introduced into the coupling algorithm and an expression for its optimal value is deduced. The iterative FEM-BEM coupling technique allows independent discretizations to be efficiently employed for both finite and boundary element methods, without any requirement of matching nodes at the common interfaces. In addition, it leads to smaller and better-conditioned systems of equations (different solvers, suitable for each sub-domain, may be employed), which do not need to be treated (inverted, triangularized etc.) at each iterative step, providing an accurate and efficient methodology.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.318-321
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• 2005

In vibro-acoustic analysis, the commercial CAE tools, such as SYSNOISE, is usually used to take into account of the coupled effects of fluid acoustics and structural vibration. The acoustic field can be solved by either FEM or BEM, while the vibration field is usually solved by FEM. The interior or exterior acoustic problems with the coupled effects of the structural boundary could be solved by the commercial tools. The commercial tools, however, could not solve the problems in case that both the interior and exterior acoustic field is coupled with the structural boundary. In this paper, a realistic method based on FEM/BEM coupling scheme is presented to analyze the acoustic radiation from the internal source in a chamber to external acoustic field through elastic structural boundary. Several numerical examples are implemented to validate the developed program.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.17 no.3
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• pp.139-170
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• 2013

We extend a p-hierarchical decomposition of the second degree finite element space of N$\acute{e}$d$\acute{e}$lec for tetrahedral meshes in three dimensions given in [1] to meshes with hexahedral elements, and derive p-hierarchical decompositions of the second degree finite element space of Raviart-Thomas in two dimensions for triangular and quadrilateral meshes. After having proved stability of these subspace decompositions and requiring certain saturation assumptions to hold, we construct a local a posteriori error estimator for fem and bem coupling of a time-harmonic electromagnetic eddy current problem in $\mathbb{R}^3$. We perform some numerical tests to underline reliability and efficiency of the estimator and test its usefulness in an adaptive refinement scheme.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.135-141
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• 1996

Numerical analysis techniques have been applied to obtain the vibroacoustic characteristics of the simplified model of a passenger-car cabin. Two kinds of coupled vibration-acoustic analysis, such as one-way coupling and full coupling, have been carried out via the interface between the results of vibration analysis by FEM and acoustic analysis by BEM. The comparison of two coupled analysis results show the fluid-structure interaction in terms of the coupled effect of the vibration and noise.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1383-1391
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• 1996

The steady-state response for a coupled structure-acoustic-cavity systme has been investigated by numerical technique using a directly coupled finite element method(FEM) and Boundary Element Method(BEM) model. The Laplace tranformed matrix equations for the structure and the acoustic cavity are coupled directly satisfying the necessary equilibrium and compatibility conditions. The coupled FEM-BEM code is verified by comparing its prediction for an example with known analytical, numerical and experimental results. The example involves a coupled structure-acoustic-cavity system which is a box-type cavity with one end as experimentally excited pinned-pinned plate.

• Coupled systems mechanics
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• v.1 no.1
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• pp.19-37
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• 2012

In this work, the iterative coupling of finite element and boundary element methods for the investigation of coupled fluid-fluid, solid-solid and fluid-solid wave propagation models is reviewed. In order to perform the coupling of the two numerical methods, a successive renewal of the variables on the common interface between the two sub-domains is performed through an iterative procedure until convergence is achieved. In the case of local nonlinearities within the finite element sub-domain, it is straightforward to perform the iterative coupling together with the iterations needed to solve the nonlinear system. In particular, a more efficient and stable performance of the coupling procedure is achieved by a special formulation that allows to use different time steps in each sub-domain. Optimized relaxation parameters are also considered in the analyses, in order to speed up and/or to ensure the convergence of the iterative process.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.10a
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• pp.132-132
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• 1997

The influence of the dam-reservoir interaction on the seismic response of concrete dam is studied. The dam body is assumed to behave elastically and modeled by FEM. The impounded water is assumed to be inviscid and compressible fluid and modeled by BEM. The seismic response of dam-reservoir system is analyzed by coupling two regions : the dam body and reservoir.

• Journal of Mechanical Science and Technology
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• v.15 no.5
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• pp.555-561
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• 2001

A new approach to analyze the multi-domain acoustic system divided and enclosed by flexible structures is presented in this paper. The boundary element formulation of the Helmholtz integral equation is used for the internal fields and the finite element formulation for the structures surrounding the fields. We developed a numerical analysis program for the structural-acoustic coupling problems of the multi-domain system, in which boundary conditions such as the continuity of normal particle velocity and sound pressure in the structural interfaces between Field 1 and Field 2 are not needed. The validity of the numerical analysis program is verified by comparing the numerical results with the experimental ones. Example problems are included to investigate the characteristics of the coupled multi-domain system.