J. Herrmann¹, M. Junge¹, L. Gaul¹

CMES-Computer Modeling in Engineering & Sciences, Vol.86, No.6, pp. 487-504, 2012, DOI:10.3970/cmes.2012.086.487

Abstract The influence of an acoustic field on the dynamic behavior of a flexible structure is a common issue in automotive applications. An example is the pressure-induced structure-borne sound of piping and exhaust systems. Efficient model order reduction and substructuring techniques accelerate the finite element analysis and enable the vibroacoustic optimization of such complex systems with acoustic fluid-structure interaction. This research reviews the application of the Craig-Bampton and the Rubin method to fluid-structure coupled systems and presents two automotive applications. First, a fluid-filled piping system is assembled by substructures or superelements according to the Craig-Bampton method. Fluid and structural partitions are… More >

Min Ki Kim¹, Seung Jo Kim²

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.4, pp. 297-332, 2012, DOI:10.3970/cmes.2012.084.297

Abstract Hybrid parallelization of multifrontal solution method and its parallel performances in a multicore distributed parallel computing architecture are represented in this paper. To utilize a state-of-the-art multicore computing architecture, parallelization of the multifrontal method for a symmetric multiprocessor machine is required. Multifrontal method is easier to parallelize than other direct solution methods because the solution procedure implies that the elimination of unknowns can be executed simultaneously. This paper focuses on the multithreaded parallelism and mixing distributed algorithm and multithreaded algorithm together in a unified software. To implement the hybrid parallelized algorithm in a distributed shared memory environment, two innovative ideas… More >

Ryuta Imai¹, Masatoshi Nakagawa²

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.3, pp. 253-282, 2012, DOI:10.3970/cmes.2012.084.253

Abstract In order to evaluate seismic response of fast breeder reactors, finite element analysis for core vibration with contact/impact is performed so far. However a full model analysis of whole core vibration requires huge calculation times and memory sizes. In this research, we propose an acceleration method of reducing the number of degrees of freedom to be solved until converged for nonlinear contact problems. Furthermore we show a sufficient condition for the algorithm to work well and discuss its efficiency and a generalization of the algorithm. In particular we carry out the full model analysis to show that our method can… More >

Dan Ma, Xianbiao Mao, Chong Li, Feng Du

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.6, pp. 561-574, 2012, DOI:10.3970/cmes.2012.083.561

Abstract Water resisting key strata (WRKS) is one of the most important structures in green coal mining engineering, which has the functions of water-preserved mining and disaster prevention of water inrush, while elastic WRKS is treated as one of the problems for elastic plates in this paper. The existing literatures on elastic plates have largely restricted to different engineering but minority in coal mining engineering. Based on the mechanical models of clamped circular plate with sub-uniform load and simply supported by a concentrated force for elastic WRKS, using the boundary integral equations which is obtained by the natural boundary reduction, this… More >

Ju’e Yang¹, Dehao Yu²

CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.3, pp. 311-330, 2011, DOI:10.3970/cmes.2011.073.311

Abstract In this paper, we introduce a domain decomposition method with non-matching grids for a certain nonlinear interface problem in unbounded domains. To solve this problem, we discuss a new coupling of finite element method(FE) and natural boundary element(NBE). We first derive the optimal energy error estimate of finite element approximation to the coupled FEM-NBEM problem. Then we use a dual basis multipier on the interface to provide the numerical analysis with non-matching grids.Finally, we give some numerical examples further to confirm our theoretical results. More >

Quan Zheng², Jing Wang², Jing-ya Li²

CMES-Computer Modeling in Engineering & Sciences, Vol.72, No.2, pp. 103-114, 2011, DOI:10.3970/cmes.2011.072.103

Abstract This paper investigates the coupling method of the finite element and the natural boundary element using an elliptic artificial boundary for solving exterior anisotropic problems, and obtains a new error estimate that depends on the mesh size, the location of the elliptic artificial boundary, the number of terms after truncating from the infinite series in the integral. Numerical examples are presented to demonstrate the effectiveness and the properties of this method. More >

Paweł Dłotko¹, Ruben Specogna²

CMES-Computer Modeling in Engineering & Sciences, Vol.60, No.3, pp. 247-278, 2010, DOI:10.3970/cmes.2010.060.247

Abstract The systematic potential design is of high importance in computational electromagnetics. For example, it is well known that when the efficient eddy-current formulations based on a magnetic scalar potential are employed in problems which involve conductive regions with holes, the so-calledthick cutsare needed to make the boundary value problem well defined. Therefore, a considerable effort has been invested over the past twenty-five years to develop fast and general algorithms to compute thick cuts automatically. Nevertheless, none of the approaches proposed in literature meet all the requirements of being automatic, computationally efficient and general. In this paper, an automatic, computationally efficient… More >

M. A. Kelmanson¹ and M. C. Tenwick¹

CMES-Computer Modeling in Engineering & Sciences, Vol.55, No.2, pp. 191-210, 2010, DOI:10.3970/cmes.2010.055.191

Abstract A method is presented for improving the accuracy of the widely used Gauss-Legendre Nyström method for determining approximate solutions of Fredholm integral equations of the second kind on finite intervals. The authors' recent continuous-kernel approach is generalised in order to accommodate kernels that are either singular or of limited continuous differentiability at a finite number of points within the interval of integration. This is achieved by developing a Gauss-Jacobi Nyström method that moreover includes a mean-value estimate of the truncation error of the Hermite interpolation on which the quadrature rule is based, making it particularly accurate at low orders. A… More >

E. Brusa¹, E. Franceschinis², S. Morsut²

CMES-Computer Modeling in Engineering & Sciences, Vol.42, No.2, pp. 75-106, 2009, DOI:10.3970/cmes.2009.042.075

Abstract Electrodes motion and positioning are critical issues of the Electric Arc Furnace (EAF) operation in steelmaking process. During the melting process electrode is exposed to some impulsive and harmonic forces, superimposing to the structure's static loading. Unfortunately, structural vibration may interact with the electric arc regulation, because of the dynamic resonance. Instability in the furnace power supplying and dangerous electrode breakage may occur as a consequence of those dynamic effects. In this paper the dynamic behaviour of a real EAF structure is discussed and some numerical models are proposed. Available experimental data, collected by a monitoring system on a real… More >

Olivier Ricou¹, Michel Bercovier²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.1, pp. 87-102, 2002, DOI:10.3970/cmes.2002.003.087

Abstract In this article, we present a method of reduction of the dimension of the Stokes equations by one in a quasi-cylindrical domain. It takes the special shape of the domain into account by the use of a projection onto a space of polynomials defined over the thickness. The polynomials are defined to fit as well as possible with the variables they approximate. Hence, this method restricted to the first polynomial, recovers the Hele-Shaw approximation.
The convergence of the approximate solution to the continuous one is shown. Under a regularity hypothesis, we also obtain error estimates.
A description of… More >