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  • Open Access

    ARTICLE

    Application of Meshless Local Petrov-Galerkin (MLPG) to Problems with Singularities, and Material Discontinuities, in 3-D Elasticity

    Q. Li1, S. Shen1, Z. D. Han1, S. N. Atluri1

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.5, pp. 571-586, 2003, DOI:10.3970/cmes.2003.004.571

    Abstract In this paper, a truly meshless method, the Meshless Local Petrov-Galerkin (MLPG) Method, is developed for three-dimensional elasto-statics. The two simplest members of MLPG family of methods, the MLPG type 5 and MLPG type 2, are combined, in order to reduce the computational requirements and to obtain high efficiency. The MLPG5 method is applied at the nodes inside the 3-D domain, so that any domain integration is eliminated altogether, if no body forces are involved. The MLPG 2 method is applied at the nodes that are on the boundaries, and on the interfaces of material More >

  • Open Access

    ARTICLE

    Molecular-Dynamics Analysis of Grain-Boundary Grooving in Interconnect Films with Underlayers

    T. Iwasaki1 and H. Miura1

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.5, pp. 551-558, 2003, DOI:10.3970/cmes.2003.004.551

    Abstract We have developed a molecular-dynamics technique for investigating migration-induced failures in interconnect films for ULSIs. This technique was used to simulate grain-boundary grooving in Al and Cu films. The simulations showed that the grain-boundary grooves are formed by atomic diffusion at the grain boundary. To clarify what kind of underlay material is effective in suppressing this diffusion, we calculated the dependence of groove depth on the kind of underlay material. The calculation showed that the groove depth of the Al film decreases in the order: Al/Ta, Al/W, and Al/TiN while that of the Cu film More >

  • Open Access

    ARTICLE

    A Conservative Time Integration Scheme for Dynamics of Elasto-damaged Thin Shells

    L. Briseghella1, C. Majorana1, P. Pavan1

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.2, pp. 273-286, 2003, DOI:10.3970/cmes.2003.004.273

    Abstract Some aspects of the application of a conservative time integration scheme to the non-linear dynamics of elasto-damaged thin shells are presented. The main characteristic of the scheme is to be conservative, in the sense that it allows the time-discrete system to preserve the basic laws of continuum, namely the balance of the linear and angular momenta as well as the fulfilment of the second law of thermodynamic. Here the method is applied to thin shells under large displacements and rotations. The constitutive model adopted is built coupling the linear elastic model of De Saint Venant-Kirchhoff More >

  • Open Access

    ARTICLE

    A Buckling and Postbuckling Analysis of Rods Under End Torque and Compressive Load

    Wen Yi Lin1, Kuo Mo Hsiao2

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.2, pp. 259-272, 2003, DOI:10.3970/cmes.2003.004.259

    Abstract The buckling and postbuckling behavior of spatial rods under different types of end torque and compressive axial force is investigated using finite element method. All coupling among bending, twisting, and stretching deformations for beam element is considered by consistent second-order linearization of the fully geometrically nonlinear beam theory. However, the third order term of the twist rate is also considered. An incremental-iterative method based on the Newton-Raphson method combined with constant arc length of incremental displacement vector is employed for the solution of nonlinear equilibrium equations. The zero value of the tangent stiffness matrix determinant More >

  • Open Access

    ARTICLE

    Accuracy of Co-rotational Formulation for 3-D Timoshenko's Beam

    M. Iura1, Y. Suetake2, S. N. Atluri3

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.2, pp. 249-258, 2003, DOI:10.3970/cmes.2003.004.249

    Abstract An accuracy of finite element solutions for 3-D Timoshenko's beams, obtained using a co-rotational formulation, is discussed. The co-rotational formulation has often been used with an assumption that the relative deformations are small. A fundamental question, therefore, has been raised as to whether or not the numerical solutions obtained approach the solutions of the exact theory. In this paper, from theoretical point of view, we investigate the accuracy of the co-rotational formulation for 3-D Timoshenko's beam undergoing finite strains and finite rotations. It is shown that the use of the conventional secant coordinates fails to More >

  • Open Access

    ARTICLE

    Element Coordinates and the Utility in Large Displacement Analysis of a Space Frame

    K. Ijima1, H. Obiya1, S. Iguchi2, S. Goto2

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.2, pp. 239-248, 2003, DOI:10.3970/cmes.2003.004.239

    Abstract Defining element coordinates in space frame, element end deformations become statically clear from the energy principle. Therefore, the deformations can be expressed by nodal displacement without any approximation. The paper indicates that the exact expressions of the deformations and the geometrical stiffness strictly based on the equations makes large displacement analysis of space frame possible with robustness on the computation. More >

  • Open Access

    ARTICLE

    On Deformation of an Euler-Bernolli Beam Under Terminal Force and Couple

    P.B. Béda1

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.2, pp. 231-238, 2003, DOI:10.3970/cmes.2003.004.231

    Abstract The paper studies the behavior of a spatial Euler-Bernoulli beam loaded by a terminal thrusting force and a couple. The classical Clebsch-Kirchhoff equilibrium equations are written by using appropriate angular coordinates describing the finite rotations of the local frames attached to each cross-sections of the beam with respect to a fixed system. When we have geometric boundary conditions at one end and dynamic boundary conditions (a force and a couple) at the other the set of equilibrium equations form and initial value probem which can easily be solved with standard Runge-Kutta method. More >

  • Open Access

    ARTICLE

    Finite Rotations and large Strains in Finite Element Shell Analysis

    Y. Başar, O. Kintzel1

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.2, pp. 217-230, 2003, DOI:10.3970/cmes.2003.004.217

    Abstract The objective of this contribution is the development of a finite element model for finite rotation and large strain analysis of thin walled shells involving geometry intersections. The shell configuration is described by a linear polynomial in the thickness coordinate. The director of the shell is multiplicatively decomposed into a stretching parameter and an inextensible unit vector whose rotation is accomplished by an updated-rotation formulation. A rotation vector with three independent components is used throughout the shell which permits advantageously to consider smooth shells and compound shells by a unified procedure. This formulation is introduced More >

  • Open Access

    ARTICLE

    A Boundary Element Method for Acoustic Scattering from Non-axisymmetric and Axisymmetric Elastic Shells

    J. P. Agnantiaris1, D. Polyzos1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.1, pp. 197-212, 2003, DOI:10.3970/cmes.2003.004.197

    Abstract A Boundary Element Method (BEM), for the three-dimensional solution of both non-axisymmetric and axisymmetric coupled acoustic-elastic problems in the frequency domain, is presented. The present BEM makes use of the Burton and Miller integral equation for infinite acoustic spaces, while elastic structures are dealt with the standard boundary integral equation of elastodynamics. The axisymmetric formulation involves the use of the fast Fourier transform algorithm. Highly accurate numerical algorithms are used for the evaluation of singular integrals, while nearly singular integrals are treated, also with high accuracy, through the use of practical numerical techniques, for both More >

  • Open Access

    ARTICLE

    A Mathematical Framework Towards a Unified Set of Discontinuous State-Phase Hierarchical Time Operators for Computational Dynamics

    R.Kanapady1, K.K.Tamma2

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.1, pp. 103-118, 2003, DOI:10.3970/cmes.2003.004.103

    Abstract Of general interest here is the time dimension aspect wherein discretized operators in time may be continuous or discontinuous; and of particular interest and focus here is the design of time discretized operators in the context of discontinuous state-phase for computational dynamics applications. Based on a generalized bi-discontinuous time weighted residual formulation, the design leading to a new unified set of hierarchical energy conserving and energy dissipating time discretized operators are developed for the first time that are fundamentally useful for time adaptive computations for dynamic problems. Unlike time discontinuous Galerkin approaches, the design is… More >

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