António Tadeu¹, Julieta António and Nuno Simões

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.1, pp. 43-58, 2004, DOI:10.3970/cmes.2004.006.043

Abstract This Analytical Green's functions for the steady-state response of homogeneous three-dimensional unbounded, half-space, slab and layered solid media subjected to a spatially sinusoidal harmonic heat line source are presented. In the literature, this problem is frequently referred to as the two-and-a-half dimensional fundamental solution or 2.5D Green's functions.
The proposed equations are theoretically interesting in themselves and they are also useful as benchmark results for validating numerical applications. They are also of great practical use in the formulation of three dimensional heat transfer problems in layered solid formations using integral transform methods and/or boundary elements.… More >

W. J. Mansur¹, A. I. Abreu¹, J. A. M. Carrer¹

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.1, pp. 31-42, 2004, DOI:10.3970/cmes.2004.006.031

Abstract This work is concerned with the computation of the contribution of initial conditions in two-dimensional (2D) frequency-domain analysis of transient scalar wave propagation problems with the corresponding Boundary Element Method (BEM) formulation. The paper describes how pseudo-forces, represented by generalized functions, can replace the initial conditions, related to the potential and its time derivative. The generation of such pseudo-forces is the subject of a detailed discussion. The formulation presented here carries out Discrete Fourier Transform (Direct: DFT, and Inverse: IDFT) via FFT (Fast Fourier Transform) algorithms. At the end of the paper four examples are More >

J. H. Jackson¹, A. S. Kobayashi², S. N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.1, pp. 17-30, 2004, DOI:10.3970/cmes.2004.006.017

Abstract The T_ε^*  integral was calculated numerically along an extending, tunneling crack front in an 8 mm thick, aluminum three-point bend (3PB) specimen, using a numerical model driven by experimentally obtained surface displacements. The model provided input to a contour integration for the T_ε^*  integral, via the Equivalent Domain Integral (EDI) method with incremental plasticity. Validity of the analysis was ensured by the agreement of the T_ε^*  integral obtained on the surface (plane stress) and the plane stress values from previous studies. T_ε^*   was observed to decrease from the outer surface of the specimen to More >

Ch,ra S. Yerramalli¹, Anthony M. Waas²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.1, pp. 1-16, 2004, DOI:10.3970/cmes.2004.006.001

Abstract Results from a 3D finite element based study of the compression response of unidirectional fiber reinforced polymer matrix composites (FRPC) are presented in this paper. The micromechanics based study was used to simulate the compressive response of glass and carbon fiber reinforced polymer matrix composites, with a view to understanding the effect of fiber diameter on compression strength. Results from the modeling and simulation indicate the presence of a complex three dimensional stress state in the matrix of the FRPC. Results from the simulation highlight the role of fiber diameter on the compressive response of More >

Wan-Sul Lee, Kie-Chan Kwon, Bong-Kyu Kim, Ji-Hyon Cho, Sung-Kie Youn¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.3, pp. 279-286, 2004, DOI:10.3970/cmes.2004.005.279

Abstract A numerical approach for eigenvalue analysis of the electrostatically tunable micro-mechanical actuators is presented. An efficient algorithm for calculating the natural frequency shifting in the micro-mechanical actuators due to applied DC turning voltage is proposed. In the calculations of the coupled field problem, the three-dimensional FEM/BEM approaches and iterative staggered algorithm are employed. The numerical examples for actually fabricated actuators are presented and the numerical analysis results are compared with experimental data. More >

W. Uddin¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.3, pp. 269-278, 2004, DOI:10.3970/cmes.2004.005.269

Abstract This paper presents the results of a three-dimensional finite element study to simulate impacts of the models of a car and a pickup truck against a model of modified thrie-beam guardrail and to analyze the crashworthiness of the roadside guardrail. Nonlinear springs were used to simulate the rotation of the post below ground level. The simulation results of an event of a pickup truck impacting the modified thrie-beam guardrail model are presented. The ``reduced'' version of the pickup truck model is redirected after impact and leaves the guardrail without any significant problem. These results compare More >

gping Shen¹, S. N. Atluri¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.3, pp. 235-256, 2004, DOI:10.3970/cmes.2004.005.235

Abstract A multiscale simulation technique based on the MLPG methods, and finite deformation mechanics, is developed, implemented, and tested. Several alternate time-dependent interfacial conditions, between the atomistic and continuum regions, are systematically studied, for the seamless multiscale simulation, by decomposing the displacement of atoms in the equivalent-continuum region into long and short wave-length components. All of these methods for enforcing the interface conditions can ensure the passage of information accurately between the atomistic and continuum regions, while they lead to different performances at short wavelengths. The presently proposed Solution Method 2 reduces the phonon reflections at More >

A. Rama Mohan Rao¹, T.V.S.R. Appa Rao², B. Dattaguru³

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.3, pp. 213-234, 2004, DOI:10.3970/cmes.2004.005.213

Abstract This paper presents an algorithm for automatic partitioning of unstructured meshes for parallel finite element computations employing float-encoded genetic algorithms (FEGA). The problem of mesh partitioning is represented in such a way that the number of variables considered in the genome (chromosome) construction is constant irrespective of the size of the problem. In order to accelerate the computational process, several acceleration techniques like constraining the search space, local improvement after initial global partitioning have been attempted. Finally, micro float-encoded genetic algorithms have been developed to accelerate the computational process. More >

S. Choi¹, M.D. Marcozzi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.3, pp. 201-212, 2004, DOI:10.3970/cmes.2004.005.201

Abstract The general intractability of derivative security pricing models to numerical techniques arguably remains one of the preeminant problems of mathematical finance. In particular, the valuations of such models may be represented as solutions of variational inequalities of evolutionary type typically characterized by their high number of degrees of freedom, unbounded domains, and asymptotic behavior. We consider the application of Multi-Quadratic Radial Basis Functions (MQ-RBF) to the problem of option pricing. More >

W.M.G.. So¹, K.J. Lau¹, S.W. Ng¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.3, pp. 189-200, 2004, DOI:10.3970/cmes.2004.005.189

Abstract A new finite element analysis procedure is implemented for the determination of complex stress intensity factors in interfacial cracks. Only nodal displacements and strain energies of the near-crack-tip elements are involved in this procedure so that element stiffness matrices need not be made available. The method is first tested using a closed form solution for infinite media to obtain a suitable finite element mesh. It is then applied to finite plates and four-point bending specimens containing interfacial cracks. In cases where reference values are available for comparison, good agreement of results can be obtained with More >