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  • Open Access

    ARTICLE

    Analysis of Partially Concrete-Filled Steel Tubular Columns subjected to Cyclic Loadings

    T. Ishizawa1, M. Iura1

    CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.3, pp. 121-130, 2006, DOI:10.3970/cmes.2006.011.121

    Abstract A one-dimensional model is proposed for numerical analysis of partially concrete-filled steel tubular (PCFST) columns subjected to cyclic loadings. The present formulation does not require experimental results nor shell analysis to obtain the constitutive equation of the model. The material properties and dimensions of PCFST columns are required for numerical analysis of the present model. The PCFST columns are assumed to consist of elastic beam and base plastic-hinge region in which steel local buckling is observed. Two parameters are introduced in order to express hardening phenomena of PCFST columns subjected to cyclic loading. Resisting forces due to concrete filled in… More >

  • Open Access

    ARTICLE

    A transport model based on kinetic theory for water vapor separation in hollow fiber membranes

    D. Bergmair1,2, S. J. Metz1, H. C. de Lange2, A. A. van Steenhoven2

    CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.1, pp. 1-15, 2013, DOI:10.3970/cmes.2013.091.001

    Abstract A method to predict the permeation of water vapor, present in a laminar flowing humid carrier gas, through a hollow fiber membrane is presented. The method uses simulation particles that move like molecules, according to the kinetic gas theory, but carry the physical properties of an ensemble of molecules which they statistically represent. With this approach an ideal operational window for membrane modules can be found and parameters tested for, can be varied over orders of magnitude. The results show that the right dimensioning is essential for the efficient use of the membrane area. More >

  • Open Access

    ARTICLE

    A Generalized FEM Model for Fiber Structural and Mechanical Performance in Fabrication of Slender Yarn Structures

    Sheng Yan Li1, Bin Gang Xu1,2, Xiao Ming Tao1, Hong Hu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.77, No.1, pp. 33-56, 2011, DOI:10.3970/cmes.2011.077.033

    Abstract Slender yarn structure made from natural fibers, nano-fibers, carbon nanotubes or other types of fibrous materials is all formed by twisting an assembly of short or long fibers and its performance is significantly influenced by the physical behavior of these fibers in the slender yarn forming region - a small triangle area called spinning triangle. In this paper, a new generalized FEM model of spinning triangle has been developed to theoretically analyze the fiber structural and mechanical performance in fabrication of these slender yarn structures. In this proposed model, a geometrical model of spinning triangle is developed and the initial… More >

  • Open Access

    ARTICLE

    Modeling and Simulation of Fiber Reinforced Polymer Mold Filling Process by Level Set Method

    Binxin Yang1, Jie Ouyang1, Tao Jiang1, Chuntai Liu2

    CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.3, pp. 191-222, 2010, DOI:10.3970/cmes.2010.063.191

    Abstract A gas-solid-liquid three-phase model is proposed for fiber reinforced composites mold filling process. The fluid flow is described in Eulerian coordinate while the dynamics of fibers is described in Langrangian coordinate. The interaction of fluid flow and fibers are enclosed in the model. The influence of fluid flow on fibers is described by the resultant forces imposed on fibers and the influence of fibers on fluid flow is described by the momentum exchange source term in the model. A finite volume method coupled with a level set method for viscoelastic-Newtonian fluid flow is used to solve the model. The direct… More >

  • Open Access

    ARTICLE

    A 3D Numerical Model for a Flexible Fiber Motion in Compressible Swirling Airflow

    Hui-Fen Guo1,2, Bin-Gang Xu1,3

    CMES-Computer Modeling in Engineering & Sciences, Vol.61, No.3, pp. 201-222, 2010, DOI:10.3970/cmes.2010.061.201

    Abstract A numerical method is developed for modeling the dynamics of a flexible fiber immersed in a compressible swirling flow. The modeling approach is based on combining an Eulerian finite volume formulation for the fluid flow and a Lagrangian small-deformation formulation for the dynamics of the fiber. The fiber is modeled as a chain of beads connected through mass-less rods. The bending and twisting deformation of the fiber are represented by the displacements of the successive beads. A computational strategy is proposed for the computation of the fluid parameters at the center of discrete fiber sections. To deal with the fiber-wall… More >

  • Open Access

    ARTICLE

    Micromechanics-Based Fiber-Bridging Analysis of Strain-Hardening Cementitious Composite Accounting for Fiber Distribution

    B.Y. Lee1, Y. Lee2, J.K.Kim3, Y.Y.Kim4

    CMES-Computer Modeling in Engineering & Sciences, Vol.61, No.2, pp. 111-132, 2010, DOI:10.3970/cmes.2010.061.111

    Abstract In the present work, a micromechanics-based fiber-bridging constitutive model that quantitatively takes into consideration the distribution of fiber orientation and the number of fibers, is derived and a fiber-bridging analysis program is developed. An image processing technique is applied to evaluate the fiber distribution characteristics of four different types of strain-hardening cementitious composites. Then, the fiber-bridging curves obtained from image analysis are compared with those obtained from the assumption of two- and three-dimensional fiber distributions. The calculated ultimate tensile strains are also compared with experimental results. Test results showed that the tensile behavior of strain-hardening cementitious composites can be more… More >

  • Open Access

    ARTICLE

    Stability Loss in Nanotube Reinforced Composites

    A.N. Guz, V.A. Dekret1

    CMES-Computer Modeling in Engineering & Sciences, Vol.49, No.1, pp. 69-80, 2009, DOI:10.3970/cmes.2009.049.069

    Abstract The two models in the three-dimensional theory of stability of the nanotube reinforced composite materials are discussed. The model of "infinite fibers" and the model of "short fibers" are considered. The primary objective is attended to "short fibers" model. All results are obtained in the framework of the three-dimensional linearized theory of stability of deformable bodies. More >

  • Open Access

    ARTICLE

    Development of a Numerical Toolbox for the Computer Aided Design of Composite Over-Wrapped Pressure Vessels

    Eugenio Brusa1, Matteo Nobile2

    CMES-Computer Modeling in Engineering & Sciences, Vol.48, No.2, pp. 155-190, 2009, DOI:10.3970/cmes.2009.048.155

    Abstract Lightness of high pressure vessels is currently assured by composite materials. Construction of over-wrapped composite pressure vessels with inner metallic liner is for instance compatible with standards requirements of the hydrogen technology of energy storage. Therefore a typical layout manufactured by some industries consists of a cylindrical vessel with covering of carbon-epoxy laminates and metallic impermeable liner. To allow the filament winding of the composite fibres are used hoop and helical layers, respectively. A single nozzle is usually built. It requires that the vessel material is reinforced. This need imposes to have a variable thickness in the composite layer. In… More >

  • Open Access

    ARTICLE

    Optimization of a Sandwich Structure Using a Genetic Algorithm

    M.R. Khoshravan1, M. Hosseinzadeh1

    CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.2, pp. 179-206, 2009, DOI:10.3970/cmes.2009.045.179

    Abstract A sandwich panel's optimum core height and composite face thickness, under defined loading, have been computed in order to reach the structure's lowest weight and highest stiffness. The Tsai-Hill criterion was used in order to control the support of transverse loading by the panel. Regarding the relationships in the sandwich materials, the studied material was modeled with the MATLAB package. The Genetic Algorithm (GA) that is based on statistics was used. Our goal was to obtain the best methods of the GA in order to present an optimization method for the sandwich structure. Hence, a sensibility analysis was performed. In… More >

  • Open Access

    ARTICLE

    On the solution method for problems related to the micro-mechanics of a periodically curved fiber near a convex cylindrical surface

    Surkay D. Akbarov1,2,3, A. R. Mamedov3

    CMES-Computer Modeling in Engineering & Sciences, Vol.42, No.3, pp. 257-296, 2009, DOI:10.3970/cmes.2009.042.257

    Abstract Within the scope of the piecewise homogeneous body model through the use of the three-dimensional geometrically non-linear exact equations of the theory of elasticity, an approach for the investigation of problems with the micromechanics of a periodically curved fiber near the free convex cylindrical surface is proposed and employed. The main difficulties in finding the solution to these problems are caused by the impossibility of employing the summation theorem for cylindrical functions to satisfy the boundary conditions on the cylindrical surface. For this purpose the cosine and sine Fourier series presentation of the sought values is proposed to satisfy the… More >

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