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  • Open Access

    ARTICLE

    Methodology for Numerical Simulation of Trabecular Bone Structures Mechanical Behavior

    M.A. Argenta1, A.P. Gebert2, E.S. Filho3, B.A. Felizari4, M.B. Hecke5

    CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.3&4, pp. 159-182, 2011, DOI:10.3970/cmes.2011.079.159

    Abstract Various methods in the literature proposesequations to calculate the stiffness as a function of density of bone tissue such as apparent density and ash density among others[Helgason, Perilli, Schileo, Taddei, Brynjolfsson and Viceconti, 2008]. Other ones present a value of an equivalent elasticity modulus, obtained by statistical adjustments of curves generated through mechanical compression tests over various specimens[Chevalier, Pahr, Allmer, Charlebois and Zysset, 2007; Cuppone, Seedhom, Berry and Ostell, 2004]. Bone tissue is a material withdifferent behaviors according to the scale of observation. It has a complex composite hierarchical structure, which is responsible for assign optimal mechanical properties. Its characteristics,… More >

  • Open Access

    ARTICLE

    The Configuration Evolution and Macroscopic Elasticity of Fluid-filled Closed Cell Composites: Micromechanics and Multiscale Homogenization Modelling

    Lianhua Ma1, Bernard F. Rolfe2, Qingsheng Yang1,3, Chunhui Yang2,3

    CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.2, pp. 131-158, 2011, DOI:10.3970/cmes.2011.079.131

    Abstract For fluid-filled closed cell composites widely distributed in nature, the configuration evolution and effective elastic properties are investigated using a micromechanical model and a multiscale homogenization theory, in which the effect of initial fluid pressure is considered. Based on the configuration evolution of the composite, we present a novel micromechanics model to examine the interactions between the initial fluid pressure and the macroscopic elasticity of the material. In this model, the initial fluid pressure of the closed cells and the corresponding configuration can be produced by applying an eigenstrain at the introduced fictitious stress-free configuration, and the pressure-induced initial microscopic… More >

  • Open Access

    ARTICLE

    Control Volume-Radial Basis Function Solution of 2D Driven Cavity Flow in Terms of the Velocity Vorticity Formulation

    C. A. Bustamante1, W. F. Florez1, H. Power2, M. Giraldo1, A. F. Hill1

    CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.2, pp. 103-130, 2011, DOI:10.3970/cmes.2011.079.103

    Abstract The two-dimensional Navier Stokes system of equations for incompressible flows is solved in the velocity vorticity formulation by means of the Control Volume-Radial Basis Function (CV-RBF) method. This method is an improvement to the Control Volume Method (CVM) based on the use of Radial Basis Function (RBF) Hermite interpolation instead of the classical polynomial functions. The main advantages of the CV-RBF method are the approximation order, the meshless nature of the interpolation scheme and the presence of the PDE operator in the interpolation. Besides, the vorticity boundary values are computed in terms of the values of the velocity field at… More >

  • Open Access

    ARTICLE

    Meshless Unsteady Thermo-Elastoplastic Analysis by Triple-Reciprocity Boundary Element Method

    Yoshihiro OCHIAI1

    CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.2, pp. 83-102, 2011, DOI:10.3970/cmes.2011.079.083

    Abstract In general, internal cells are required to solve unsteady thermo-elasto -plastic problems using a conventional boundary element method (BEM). However, in this case, the merit of BEM, which is the easy preparation of data, is lost. The conventional multiple-reciprocity boundary element method (MRBEM) cannot be used to solve thermo-elastoplastic problems, because the distribution of initial stress cannot be determined analytically. In this paper, it is shown that two-dimensional unsteady thermo-elastoplastic problems can be solved without the use of internal cells by using the triple-reciprocity BEM and a thin plate spline. The initial stress formulation is adopted and the initial stress… More >

  • Open Access

    ARTICLE

    Predictions of Lid-Driven Flow in a Two-Dimensional Irregular Cavity: a Numerical Study

    Bruno Manoel Pasquim1, Viviana Cocco Mariani1

    CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.1, pp. 63-82, 2011, DOI:10.3970/cmes.2011.079.063

    Abstract The main aim of this study was to evaluate the capacity of a Eulerian-Lagrangian methodology (ELAFINT) to accurately deal with incompressible viscous steady flow in a domain with corners and curved boundaries. Thus, a two-dimensional lid-driven cavity with an irregular bottom was selected. The equations that govern the flow are discretized using the finite-volume method with a Cartesian grid. The evolution of the velocity fields, stream function and vorticity in the irregular cavity when the Reynolds number increases from 500 to 6000 is captured by the method under investigation. The results show that with an increase in the Reynolds number… More >

  • Open Access

    ARTICLE

    A Multi-scale Geometrical Model for Finite Element Analyses of Three-dimensional Angle-Interlock Woven Composite under Ballistic Penetration

    Kun Luan1, Baozhong Sun1, Bohong Gu1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.1, pp. 31-62, 2011, DOI:10.3970/cmes.2011.079.031

    Abstract This paper reports finite element multi-scale simulations of ballistic impact damage of three-dimensional angle-interlock woven composite (3DAWC) penetrated under a hemispherical rigid projectile. A multi-scale geometrical model of the 3DAWC was established for the numerical simulation. The multi-scale geometrical model of the 3DAWC consists two parts: one is the microstructure model and another is the continuum model. The microstructure model has the same microstructure with that of the 3DAWC composite panel, including the fiber tows' diameter, fiber tow configuration and fiber volume fraction. The continuum model has the same mechanical properties with the 3DAWC. The commercial-available finite element software package… More >

  • Open Access

    ARTICLE

    Three Dimensional Acoustic Shape Sensitivity Analysis by Means of Adjoint Variable Method and Fast Multipole Boundary Element Approach

    C.J. Zheng1, H.B. Chen1, T. Matsumoto2, T. Takahashi2

    CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.1, pp. 1-30, 2011, DOI:10.3970/cmes.2011.079.001

    Abstract A fast multipole boundary element approach to the shape sensitivity analysis of three dimensional acoustic wave problems is developed in this study based on the adjoint variable method. The concept of material derivative is employed in the derivation. The Burton-Miller formula which is a linear combination of the conventional and normal derivative boundary integral equations is adopted to cope with the non-uniqueness problem when solving exterior acoustic wave problems. Constant elements are used to discretize the boundary surface so that the strongly- and hyper-singular boundary integrals contained in the formulations can be evaluated explicitly and the numerical process can be… More >

  • Open Access

    ARTICLE

    A Constitutive Model for Porous Shape Memory Alloys Considering the Effect of Hydrostatic Stress

    Bingfei Liu1, Guansuo Dui1,2, Yuping Zhu3

    CMES-Computer Modeling in Engineering & Sciences, Vol.78, No.3&4, pp. 247-276, 2011, DOI:10.3970/cmes.2011.078.247

    Abstract A constitutive model considering the effect hydrostatic stresses induced by porosity on the macroscopic behavior of porous Shape Memory Alloys (SMAs) is developed in this paper. First, a unit-cell model is adopted to establish the constitutive relations for the porous SMAs with SMA matrix and the porosity taken to be voids. Dilatational plasticity theory is then generalized for the SMA matrix. Based on an approximation of the velocity field and the upper bound theory, an explicit yield function for the porous SMA is derived from micromechanical considerations. Finally, an example for the uniaxial response under compression of a porous Ni-Ti… More >

  • Open Access

    ARTICLE

    Numerical Design of Random Micro-Heterogeneous Materials with Functionally-Graded Effective Thermal Conductivities Using Genetic Algorithms and the Fast Boundary Element Method

    Marco Dondero1, Adrián P. Cisilino1,2, J. Pablo Tomba1

    CMES-Computer Modeling in Engineering & Sciences, Vol.78, No.3&4, pp. 225-246, 2011, DOI:10.3970/cmes.2011.078.225

    Abstract This paper introduces a numerical methodology for the design of random micro-heterogeneous materials with functionally graded effective thermal conductivities (ETC). The optimization is carried out using representative volume elements (RVEs), a parallel Genetic Algorithm (GA) as optimization method, and a Fast Multipole Boundary Element Method (FMBEM) for the evaluation of the cost function. The methodology is applied for the design of foam-like microstructures consisting of random distributions of circular insulated holes. The temperature field along a material sample is used as objective function, while the spatial distribution of the holes is the design variable. There are presented details of the… More >

  • Open Access

    ARTICLE

    Application of the OMLS Interpolation to Evaluate Volume Integrals Arising in Static Elastoplastic Analysis via BEM

    K.I. Silva1, J.C.F. Telles2, F.C. Araújo3

    CMES-Computer Modeling in Engineering & Sciences, Vol.78, No.3&4, pp. 209-224, 2011, DOI:10.3970/cmes.2011.078.209

    Abstract In this work the boundary element method is applied to solve 2D elastoplastic problems. In elastoplastic boundary element analysis, domain integrals have to be calculated to introduce the contribution of yielded zones. Traditionally, the use of internal integration cells have been adopted to evaluate such domain integrals. The present work, however, proposes an alternative cell free strategy based on the OMLS (Orthogonal Moving Least Squares) interpolation, typically adopted in meshless methods. In this approach the definition of points to compute the interpolated value of a function at a given location only depends on their relative distance, without need to define… More >

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