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  • Open Access

    ARTICLE

    Microstructural Modeling and Second-Order Two-Scale Computation for Mechanical Properties of 3D 4-Directional Braided Composites

    Zihao Yang1, Junzhi Cui2, Yufeng Nie1, Yatao Wu1, Bin Yang3, Bo Wu4

    CMC-Computers, Materials & Continua, Vol.38, No.3, pp. 175-194, 2013, DOI:10.3970/cmc.2013.038.175

    Abstract This study is concerned with the microstructural modeling and mechanical properties computation of three-dimensional (3D) 4-directional braided composites. Microstructure of the braided composite determines its mechanical properties and a precise geometry modeling of the composite is essential to predict the material properties. On the basis of microscopic observation, a new parameterized microstructural unit cell model is established in this paper. And this model truly simulates the microstructure of the braided composites. Furthermore, the mathematical relationships among the structural parameters, including the braiding angle, fiber volume fraction and braiding bitch, are derived. By using the unit More >

  • Open Access

    ARTICLE

    Simulations of Three-dimensional Thermal Residual Stress and Warpage in Injection Molding

    Xuejuan Li1,2, Jie Ouyang2,3, Wen Zhou2

    CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.6, pp. 379-407, 2013, DOI:10.3970/cmes.2013.096.379

    Abstract The three-dimensional (3D) mathematical models for thermal residual stress and warpage are proposed in injection molding, in which the temperature model is rebuilt by considering the phase-change effect to improve the computational accuracy. The 3D thermal residual stress model is transformed into the incremental displacement model so that the boundary conditions can be imposed easily. A modified finite element neural network (FENN) method is used for solving 3D warpage model based on the advantages of finite element method and neural network. The influence of phase-change on temperature is discussed. The numerical simulations of thermal residual More >

  • Open Access

    ARTICLE

    Solution of the Inverse Radiative Transfer Problem of Simultaneous Identification of the Optical Thickness and Space-Dependent Albedo Using Bayesian Inference

    D. C. Knupp1,2, A. J. Silva Neto3

    CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.5, pp. 339-360, 2013, DOI:10.3970/cmes.2013.096.339

    Abstract Inverse radiative transfer problems in heterogeneous participating media applications include determining gas properties in combustion chambers, estimating environmental and atmospheric conditions, and remote sensing, among others. In recent papers the spatially variable single scattering albedo has been estimated by expanding this unknown function as a series of known functions, and then estimating the expansion coefficients with parameter estimation techniques. In the present work we assume that there is no prior information on the functional form of the unknown spatially variable albedo and, making use of the Bayesian approach, we propose the development of a posterior… More >

  • Open Access

    ARTICLE

    Analysis of Multiple Inclusion Potential Problems by the Adaptive Cross Approximation Method

    R. Q. Rodríguez1, A.F. Galvis1, P. Sollero1, E. L. Albuquerque2

    CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.4, pp. 259-274, 2013, DOI:10.3970/cmes.2013.096.259

    Abstract Over recent years the rapid evolution of the computational power has motivated the development of new numerical techniques to account for engineering solutions. The Boundary Element Method (BEM) has shown to be a powerful numeric tool for the analysis and solution of many physical and engineering problems. However, BEM fully populated and non-symmetric system matrices implies in higher memory requirements and solution times. This work analyze the application of hierarchical matrices and low rank approximations, applying the Adaptive Cross Approximation - ACA, to multiple inclusion potential problems. The use of hierarchical format is aimed at More >

  • Open Access

    ARTICLE

    Efficient BEM Stress Analysis of 3D Generally Anisotropic Elastic Solids With Stress Concentrations and Cracks

    Y.C. Shiah1, C.L. Tan2, Y.H. Chen3

    CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.4, pp. 243-257, 2013, DOI:10.3970/cmes.2013.096.243

    Abstract The present authors have recently proposed an efficient, alternative approach to numerically evaluate the fundamental solution and its derivatives for 3D general anisotropic elasticity. It is based on a double Fourier series representation of the exact, explicit form of the Green’s function derived by Ting and Lee (1997). This paper reports on the successful implementation of the fundamental solution and its derivatives based on this Fourier series scheme in the boundary element method (BEM) for 3D general anisotropic elastostatics. Some numerical examples of stress concentration problems and a crack problem are presented to demonstrate the More >

  • Open Access

    ARTICLE

    The Far-field Green’s Integral in Stokes Flow from the Boundary Integral Formulation

    E.A. Chadwick1

    CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.3, pp. 177-184, 2013, DOI:10.3970/cmes.2013.096.177

    Abstract In boundary integral methods for Stokes flow, the far-field Green’s integral is usually taken to be zero without proof. However, this is not obviously the case, the reason being that Stokes flow is a near-field approximation and breaks down in the far-field. Here, we show that it is zero as expected by matching it to a far-field Green’s integral in Oseen flow. Hence, there are similarities to the matched asymptotic procedure matching a near-field Stokes flow to a far-field Oseen flow, except in this case a different and new procedure is required to deal with More >

  • Open Access

    ARTICLE

    Numerical Study of Polymer Composites in Contact

    L. Rodríguez-Tembleque1, A. Sáez1, F.C. Buroni1

    CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.2, pp. 131-158, 2013, DOI:10.3970/cmes.2013.096.131

    Abstract A boundary element based formulation is applied to study numerically the tribological behavior of fiber-reinforced plastics (FRP) under different frictional contact conditions, taking into account the micromechanics of FRP. Micromechanical models presented consider continuous and short fiber reinforced plastics configurations. The Boundary Element Method (BEM) with an explicit approach for fundamental solutions evaluation is considered for computing the elastic influence coefficients. Signorini’s contact conditions and an orthotropic law of friction on the potential contact zone are enforced by contact operators over the augmented Lagrangian. The proposed methodology is applied to study carbon FRP under frictional More >

  • Open Access

    ARTICLE

    Vortex Patches

    G.R. Baker1

    CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.2, pp. 91-101, 2013, DOI:10.3970/cmes.2013.096.091

    Abstract A vortex patch is a bounded region of uniform vorticity in twodimensional, incompressible, inviscid fluid flow. The streamfunction satisfies the Poisson equation with the vorticity acting as a source term. The standard formulation is to write the streamfunction as a convolution of the vorticity with the twodimensional free-space Greens function. A simple application of Greens theorem converts the area integral to a boundary integral. Numerical methods must then account for the singular nature of the boundary integral, and high accuracy is difficult when filamentation takes place, that is, when long, very thin filaments of vorticity… More >

  • Open Access

    ARTICLE

    Detailed CVFEM Algorithm for Three Dimensional Advection-diffusion Problems

    E. Tombarević1, V. R. Voller2, I. Vušanović1

    CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.1, pp. 1-29, 2013, DOI:10.3970/cmes.2013.096.001

    Abstract The Control Volume Finite Element Method (CVFEM) combines the geometric flexibility of the Finite Element Method (FEM) with the physical intuition of the Control Volume Method (CVM). These two features of the CVFEM make it a very powerful tool for solving heat and fluid flow problems within complex domain geometries. In solving problems in the two-dimensional domains the development of the CVFEM has been well documented. For the three-dimensional problems, while there is extensive reporting on the details of the numerical approximation, there is relatively sparse information on important issues related to data structure and More >

  • Open Access

    ARTICLE

    Dam-breaking Flow Simulations by Particle-based Scheme Using Logarithmic Weighting Function

    K. Kakuda1, K. Tochikubo1, J. Toyotani1

    CMES-Computer Modeling in Engineering & Sciences, Vol.95, No.5, pp. 351-367, 2013, DOI:10.3970/cmes.2013.095.351

    Abstract The application of a CPU/GPU-based particle method to dam-breaking incompressible viscous fluid flow problems is presented. The particle approach is based on the MPS (Moving Particle Semi-implicit) scheme using logarithmic weighting function to stabilize the spurious oscillatory solutions for solving the Poisson equation with respect to the pressure fields by using GPU-based SCG (Scaled Conjugate Gradient) method. The physics-based computer graphics for the results of three-dimensional simulation consist of the POV-Ray (Persistence of Vision Raytracer) rendering using marching cubes algorithm as polygonization. Numerical results demonstrate the workability and the validity of the present approach through More >

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