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  • Open Access


    Modeling of Electric Double Layer Effects through Pressure-driven Microchannel Flows

    E.Y.K. Ng1, S.T. Poh 2

    CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.3, pp. 351-366, 2002, DOI:10.3970/cmes.2002.003.351

    Abstract Advances in microfabrication technology have allowed the use of microchannels in ultra compact, very efficient heat exchangers, which capitalize on the channels large surface area to volume ratio, to transport high heat fluxes with small thermal resistances. One example is the cooling of microchips. However, research into microscale flow and heat transfer phenomena conducted by various researchers provided substantial experimental data and considerable evidence that the behaviour of fluid flow and heat transfer in microchannels without phase change may be different than that which normally occurs in larger more conventional sized channels.
    This paper describes a numerical analysis with… More >

  • Open Access


    Laminated Elastic Plates with Piezoelectric Sensors and Actuators

    J. Sladek1, V. Sladek1, P. Stanak1, P.H. Wen2, S.N. Atluri3

    CMES-Computer Modeling in Engineering & Sciences, Vol.85, No.6, pp. 543-572, 2012, DOI:10.3970/cmes.2012.085.543

    Abstract A meshless local Petrov-Galerkin (MLPG) method is applied to solve laminate piezoelectric plates described by the Reissner-Mindlin theory. The piezoelectric layer can be used as a sensor or actuator. A pure mechanical load or electric potential are prescribed on the top of the laminated plate. Both stationary and transient dynamic loads are analyzed here. The bending moment, the shear force and normal force expressions are obtained by integration through the laminated plate for the considered constitutive equations in each lamina. Then, the original three-dimensional (3-D) thick plate problem is reduced to a two-dimensional (2-D) problem. Nodal points are randomly distributed… More >

  • Open Access


    A Four-Node Reissner-Mindlin Shell with Assumed Displacement Quasi-Conforming Method

    Ping Hu1, Yang Xia1, Limin Tang2

    CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.2, pp. 103-136, 2011, DOI:10.3970/cmes.2011.073.103

    Abstract In this paper, an assumed displacement quasi-conforming finite element method with truncated polynomial expansions of in-domain displacements and derived expansions of strains is introduced. Based on the method a four-node quadrilateral flat shell element with complete quadratic polynomials for membrane and bending displacement fields is developed. Numerical tests are carried out for validation of the present element. The results show that the present element preserves all the advantages of the quasi-conforming i.e., explicit stiffness matrix, convenient post processing and free from membrane locking and shear locking. The tests also prove that the present element gives excellent results, especially for the… More >

  • Open Access


    A Nonlinear Dynamic Model for Periodic Motion of Slender Threadline Structures

    Jinling Long1,2, Bingang Xu1,3, Xiaoming Tao1

    CMES-Computer Modeling in Engineering & Sciences, Vol.72, No.4, pp. 273-298, 2011, DOI:10.3970/cmes.2011.072.273

    Abstract Moving slender threadline structures are widely used in various engineering fields. The dynamics of these systems is sometimes time dependent but in most cases follows a periodic pattern, and slender yarn motion in textile engineering is a typical problem of this category. In the present paper, we propose a nonlinear approach to model the dynamic behavior of slender threadline structures with a real example in the analysis of slender yarn motion in spinning. Moving boundary conditions of yarn are derived and a consequence of the perturbation analysis for the dimensionless governing equations provides the zero order approximate equation of motion… More >

  • Open Access


    A Topology Optimization of Moderately Thick Plates Based on the Meshless Numerical Method

    S.L. Li1,2, S.Y. Long1, G.Y. Li1

    CMES-Computer Modeling in Engineering & Sciences, Vol.60, No.1, pp. 73-94, 2010, DOI:10.3970/cmes.2010.060.073

    Abstract A new implementation of topology optimization for the plate described by the Reissner-Mindlin theory based on the meshless natural neighbour Petrov-Galerkin method (NNPG) is proposed in this work. The objective is to produce the stiffest plate for a given volume by redistributing the material throughout the plate. We try to couple the advantages of the meshless numerical method with the topology optimization of moderately thick plate. The numerical approach presented here is based on the solid isotropic material with penalization (SIMP) formulation of the topology optimization problem. The natural neighbour interpolation shape function is employed to discretize both displacement and… More >

  • Open Access


    BEM Solutions for 2D and 3D Dynamic Problems in Mindlin's Strain Gradient Theory of Elasticity

    A. Papacharalampopoulos2, G. F. Karlis2, A. Charalambopoulos3, D. Polyzos4

    CMES-Computer Modeling in Engineering & Sciences, Vol.58, No.1, pp. 45-74, 2010, DOI:10.3970/cmes.2010.058.045

    Abstract A Boundary Element Method (BEM) for solving two (2D) and three dimensional (3D) dynamic problems in materials with microstructural effects is presented. The analysis is performed in the frequency domain and in the context of Mindlin's Form II gradient elastic theory. The fundamental solution of the differential equation of motion is explicitly derived for both 2D and 3D problems. The integral representation of the problem, consisting of two boundary integral equations, one for displacements and the other for its normal derivative is exploited for the proposed BEM formulation. The global boundary of the analyzed domain is discretized into quadratic line… More >

  • Open Access


    Numerical Phenomenology: Virtual Testing of the Hierarchical Structure of a Bundle of Strands

    D.P. Boso1, M. Lefik2

    CMES-Computer Modeling in Engineering & Sciences, Vol.55, No.3, pp. 319-338, 2010, DOI:10.3970/cmes.2010.055.319

    Abstract In this paper we study numerically the mechanical behaviour of wire ropes, particularly the influence of the geometrical configuration on the overall stiffness of the cables. Modelling the behaviour of a cable is a difficult problem, given the complexity of the geometrical layout, contact phenomena occurring among wires and possible yielding of the material. For this reason we pursue a "hierarchical beam approach", to substitute recursively, at each cabling stage, the bundle of wires with an equivalent single strand, having the characteristics computed from the previous level. We consider the first two levels of the bundle hierarchy and investigate the… More >

  • Open Access


    Stable Manifolds of Saddles in Piecewise Smooth Systems

    A. Colombo1, U. Galvanetto2

    CMES-Computer Modeling in Engineering & Sciences, Vol.53, No.3, pp. 235-254, 2009, DOI:10.3970/cmes.2009.053.235

    Abstract The paper addresses the problem of computing the stable manifolds of equilibria and limit cycles of saddle type in piecewise smooth dynamical systems. All singular points that are generically present along one-dimensional or two-dimensional manifolds are classified and such a classification is then used to define a method for the numerical computation of the stable manifolds. Finally the proposed method is applied to the case of a stick-slip oscillator. More >

  • Open Access


    Structural Integrity of Functionally Graded Composite Structure using Mindlin-type Element

    O.O. Oyekoya, D.U. Mba1, A.M. El-Zafrany

    CMES-Computer Modeling in Engineering & Sciences, Vol.34, No.1, pp. 55-86, 2008, DOI:10.3970/cmes.2008.034.055

    Abstract In this paper, two new Mindlin-type plate bending elements have been derived for the modelling of functionally graded plate subjected to various loading conditions such as tensile loading, in-plane bending and out-of-plane bending. The properties of the first Mindlin-type element (i.e. Average Mindlin-type element) are computed by using an average fibre distribution technique which averages the macro-mechanical properties over each element. The properties of the second Mindlin-type element (i.e. Smooth Mindlin-type element) are computed by using a smooth fibre distribution technique, which directly uses the macro-mechanical properties at Gaussian quadrature points of each element. There were two types of non-linearity… More >

  • Open Access


    Thermal Analysis of Reissner-Mindlin Shallow Shells with FGM Properties by the MLPG

    J. Sladek1, V. Sladek1, P. Solek2, P.H. Wen3, S.N. Atluri4

    CMES-Computer Modeling in Engineering & Sciences, Vol.30, No.2, pp. 77-98, 2008, DOI:10.3970/cmes.2008.030.077

    Abstract A meshless local Petrov-Galerkin (MLPG) method is applied to solve problems of Reissner-Mindlin shells under thermal loading. Both stationary and thermal shock loads are analyzed here. Functionally graded materials with a continuous variation of properties in the shell thickness direction are considered here. A weak formulation for the set of governing equations in the Reissner-Mindlin theory is transformed into local integral equations on local subdomains in the base plane of the shell by using a unit test function. Nodal points are randomly spread on the surface of the plate and each node is surrounded by a circular subdomain to which… More >

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