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  • Open Access


    Accurate MLPG Solution of 3D Potential Problems

    Giorgio Pini1, Annamaria Mazzia1, Flavio Sartoretto2,

    CMES-Computer Modeling in Engineering & Sciences, Vol.36, No.1, pp. 43-64, 2008, DOI:10.3970/cmes.2008.036.043

    Abstract Meshless methods have been explored in many 2D problems and they have been shown to be as accurate as Finite Element Methods (FEM). Compared to the extensive literature on 2D applications, papers on solving 3D problems by meshless methods are surprisingly few. Indeed, a main drawback of these methods is the requirement for accurate cubature rules. This paper focuses on the so called Meshless Local Petrov Galerkin (MLPG) methods. We show that accurate solutions of 3D potential problems can be attained, provided suitable cubature rules are identified, sparse data structures are efficiently stored, and strategies More >

  • Open Access


    Global/Local FEM-BEM Stress Analysis of Damaged Aircraft Structures

    A. Alaimo1, A. Milazzo2, C. Orlando3

    CMES-Computer Modeling in Engineering & Sciences, Vol.36, No.1, pp. 23-42, 2008, DOI:10.3970/cmes.2008.036.023

    Abstract In this paper a Hierarchical approach for the analysis of advanced aerospace structures is presented. The proposed Global/Local model uses two kind of numerical methods. The first step of the Hierarchical procedure is performed by the Finite Element code Patran/Nastran\texttrademark , using a coarse mesh to study the global structure, then the local region is analyzed by using a Boundary Element code based on the multidomain anisotropic technique. This code accurately predicts stress concentrations at crack tips with a reduction of the modeling efforts and of the computational time. The Global/Local interface code implemented allows More >

  • Open Access


    The Shape Identification Problem in Estimating the Geometry of A Three-Dimensional Irregular Internal Cavity

    Cheng-Hung Huang1, Chi-An Chen1

    CMES-Computer Modeling in Engineering & Sciences, Vol.36, No.1, pp. 1-22, 2008, DOI:10.3970/cmes.2008.036.001

    Abstract A three-dimensional shape identification problem (or inverse geometry problem) in estimating the unknown irregular shape of internal cavity by using the steepest descent method (SDM) and a general purpose commercial code CFD-RC is examined in this study based on the simulated measured temperature distributions on the outer surface by infrared thermography. The advantage of calling CFD-RC as a subroutine in the present shape identification problem lies in its characteristics of easily-handling the problem considered here since the auto mesh function of CFD-RC enables the handling of this moving boundary problem. \newline Three test cases are More >

  • Open Access


    Analysis of Dynamic Fracture with Cohesive Crack Segment Method

    H.X. Wang, S.X. Wang

    CMES-Computer Modeling in Engineering & Sciences, Vol.35, No.3, pp. 253-274, 2008, DOI:10.3970/cmes.2008.035.253

    Abstract In the meshfree cohesive crack method, the discrete crack is modeled by a set of cohesive crack segments which can be arbitrarily oriented. Propagation of the crack is achieved by activation of crack surfaces at individual nodes, so no representation of the crack surface is needed. The crack is modeled by a local enrichment of the test and trial functions with sign function, so that discontinuities are along the direction of the crack. A set of cracking rules is developed to avoid spurious cracking. More >

  • Open Access


    The Artificial Boundary Method for a Nonlinear Interface Problem on Unbounded Domain

    De-hao Yu1 ,Hong-ying Huang2

    CMES-Computer Modeling in Engineering & Sciences, Vol.35, No.3, pp. 227-252, 2008, DOI:10.3970/cmes.2008.035.227

    Abstract In this paper, we apply the artificial boundary method to solve a three-dimensional nonlinear interface problem on an unbounded domain. A spherical or ellipsoidal surface as the artificial boundary is introduced. The exact artificial boundary conditions are derived explicitly in terms of an infinite series and then the well-posedness of the coupled weak formulation in a bounded domain, which is equivalent to the original problem in the unbounded domain, is obtained. The error estimate depends on the mesh size, the term after truncating the infinite series and the location of the artificial boundary. Some numerical More >

  • Open Access


    Strength Asymmetry of Twinned Copper Nanowires under Tension and Compression

    Yongfeng Zhang1, Hanchen Huang1,2, Satya N. Atluri3

    CMES-Computer Modeling in Engineering & Sciences, Vol.35, No.3, pp. 215-226, 2008, DOI:10.3970/cmes.2008.035.215

    Abstract Molecular dynamics simulations reveal the asymmetrical yield strength of twinned copper nanowires under tension and compression. The simulation results show that the strength of nanowires depends on loading conditions, morphologies, and twin spacing. Under tensile loading condition the Schmidt factor of the leading partial is larger than that under compression. Effectively, the yield strength under tension is smaller than that under compression. When the cross-section is circular in morphology, dislocation nucleation requires larger stress, and the asymmetry of yield strength depends on the nucleation stress. When the cross section is square in morphology, dislocation nucleation More >

  • Open Access


    A Mesh-Free DRK-Based Collocation Method for the Coupled Analysis of Functionally Graded Magneto-Electro-Elastic Shells and Plates

    Chih-Ping Wu1,2, Kuan-Hao Chiu2, Yung-Ming Wang2

    CMES-Computer Modeling in Engineering & Sciences, Vol.35, No.3, pp. 181-214, 2008, DOI:10.3970/cmes.2008.035.181

    Abstract A mesh-free collocation method based on differential reproducing kernel (DRK) approximations is developed for the three-dimensional (3D) analysis of simply-supported, doubly curved functionally graded (FG) magneto-electro-elastic shells under the mechanical load, electric displacement and magnetic flux. The material properties of FG shells are firstly regarded as heterogeneous through the thickness coordinate and then specified to obey an identical power-law distribution of the volume fractions of the constituents. The novelty of the present DRK-based collocation method is that the shape functions of derivatives of reproducing kernel (RK) approximants are determined using a set of differential reproducing… More >

  • Open Access


    A Lie-Group Shooting Method Estimating Nonlinear Restoring Forces in Mechanical Systems

    Chein-Shan Liu 1

    CMES-Computer Modeling in Engineering & Sciences, Vol.35, No.2, pp. 157-180, 2008, DOI:10.3970/cmes.2008.035.157

    Abstract For an inverse vibration problem of nonlinear mechanical system to estimate displacement- and velocity-dependent restoring force, we transform the equation of motion into a parabolic type partial differential equation (PDE). Then by a semi-discretization of the PDE, the inverse vibration problem is formulated as a multi-dimensional two-point boundary value problem with unknown sources, allowing a closed-form estimation through a Lie-group shooting method to construct the restoring force surface over phase plane. Only one set of displacements measured at sampling time points is used in the estimation. The new method does not require to assume a More >

  • Open Access


    Application of Meshless Local Petrov-Galerkin (MLPG) Method in Cloth Simulation

    Weiran Yuan1,2, Yujun Chen2,3, André Gagalowicz2, Kaixin Liu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.35, No.2, pp. 133-156, 2008, DOI:10.3970/cmes.2008.035.133

    Abstract In this paper we present an approach to cloth simulation which models the deformation based on continuum mechanics and discretized with Meshless Local Petrov-Galerkin (MLPG) Method. MLPG method, which involves not only a meshless interpolation for trial functions, but also a meshless integration of the local weak form, has been considered as a general basis for the other meshless methods. By this way, the mechanical behavior of cloth is consistent and united, which is independent of the resolutions. At the same time, point sampled models, which neither have to store nor to maintain globally consistent… More >

  • Open Access


    Solutions for Incompressible Viscous Flow in a Triangular Cavity using Cartesian Grid Method

    B. M. Pasquim1, V. C. Mariani2

    CMES-Computer Modeling in Engineering & Sciences, Vol.35, No.2, pp. 113-132, 2008, DOI:10.3970/cmes.2008.035.113

    Abstract This study presents a Cartesian grid method and its application to solve a steady flow in a lid-driven triangular two-dimensional cavity. The evolution of stream function and vorticity inside a triangular lid-driven cavity, when the Reynolds number changes from 1 to 6000, is presented. For space discretization on the interior of triangular cavity orthogonal Cartesian grid is used. Then, using this grid, trapezoidal volumes appear in the interface between solid and fluid. For a suitable treatment of these volumes the Eulerian-Lagrangian methodology is used. The Navier-Stokes equations are solved numerically using finite-volume method. On the More >

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