Isa Ahmadi¹, M.M. Aghdam²

CMES-Computer Modeling in Engineering & Sciences, Vol.108, No.1, pp. 21-48, 2015, DOI:10.3970/cmes.2015.108.021

Abstract In this study, a truly meshless method based on the meshless local Petrov-Galerkin method is formulated for analysis of the elastic-plastic behavior of heterogeneous solid materials. The incremental theory of plasticity is employed for modeling the nonlinearity of the material behavior due to plastic strains. The well-known Prandtl-Reuss flow rule of plasticity is used as the constitutive equation of the material. In the presented method, the computational cost is reduced due to elimination of the domain integration from the formulation. As a practical example, the presented elastic-plastic meshless formulation is employed for micromechanical analysis of More >

Y. T. Wu¹, Y. F. Nie², Z. H. Yang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.99, No.4, pp. 297-325, 2014, DOI:10.3970/cmes.2014.099.297

Abstract Four representative multiscale methods, namely asymptotic homogenization method (AHM), heterogeneous multiscale method (HMM), variational multiscale (VMS) method and multiscale finite element method (MsFEM), for elliptic problems with multiscale coefficients are surveyed. According to the features they possess, these methods are divided into two categories. AHM and HMM belong to the up–down framework. The feature of the framework is that the macroscopic solution is solved first with the help of effective information computed in local domains, and then the multiscale solution is resolved in local domains using the macroscopic solution when necessary. VMS method andMsFEM fall More >

Leiting Dong^1,2, Satya N. Atluri^1,3

CMC-Computers, Materials & Continua, Vol.33, No.2, pp. 111-154, 2013, DOI:10.3970/cmc.2013.033.111

Abstract In this study, SGBEM Voronoi Cells (SVCs), with each cell representing a grain of the material at the micro-level, are developed for direct micromechanical numerical modeling of heterogeneous composites. Each SVC can consist of either a (each with a different) homogenous isotropic matrix, and can include micro-inhomogeneities such as inclusions, voids of a different material, and cracks. These inclusions and voids in each SVC can be arbitrarily-shaped, such as circular, elliptical, polygonal, etc., for 2D problems. Further, the cracks in each SVC can be fully-embedded, edge, branching, or intersecting types, with arbitrary curved shapes. By… More >

D.S. Liu^1,2, Z.H. Fong¹, I.H. Lin¹, Z.W. Zhuang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.6, pp. 441-468, 2013, DOI:10.3970/cmes.2013.093.441

Abstract In this study, we proposed a novel numerical technique to simulate the transient moisture diffusion process and to apply it to heterogeneous composite resins. The method is based on a heterogeneous hybrid moisture element (HHME), with properties determined through an equivalent hybrid moisture capacitance/ conductance matrix that was calculated using the conventional finite element formulation in space discretization and the q-method in time discretization, with similar mass/stiffness properties and matrix condensing operations. A coupled HHME with finite element scheme was developed and implemented in the computer code by using the commercial software MATLAB to analyze… More >

Leiting Dong^1,2, Salah H. Gamal³, Satya N. Atluri^2,4

CMC-Computers, Materials & Continua, Vol.37, No.1, pp. 1-21, 2013, DOI:10.3970/cmc.2013.037.001

Abstract In this paper, a simple and reliable procedure of stochastic computation is combined with the highly accurate and efficient Trefftz Computational Grains (TCG), for a direct numerical simulation (DNS) of heterogeneous materials with microscopic randomness. Material properties of each material phase, and geometrical properties such as particles sizes and distribution, are considered to be stochastic with either a uniform or normal probabilistic distributions. The objective here is to determine how this microscopic randomness propagates to the macroscopic scale, and affects the stochastic characteristics of macroscopic material properties. Four steps are included in this procedure: (1)… More >

Leiting Dong¹, Satya N. Atluri1¹

CMC-Computers, Materials & Continua, Vol.30, No.1, pp. 39-82, 2012, DOI:10.3970/cmc.2012.030.039

Abstract In this paper, as an extension to the authors's work in [Dong and Atluri (2011a,b, 2012a,b,c)], three-dimensional Trefftz Voronoi Cells (TVCs) with ellipsoidal voids/inclusions are developed for micromechanical modeling of heterogeneous materials. Several types of TVCs are developed, depending on the types of heterogeneity in each Voronoi Cell(VC). Each TVC can include alternatively an ellipsoidal void, an ellipsoidal elastic inclusion, or an ellipsoidal rigid inclusion. In all of these cases, an inter-VC compatible displacement field is assumed at each surface of the polyhedral VC, with Barycentric coordinates as nodal shape functions. The Trefftz trial displacement… More >

L. Dong¹, S. N. Atluri¹

CMC-Computers, Materials & Continua, Vol.29, No.2, pp. 169-212, 2012, DOI:10.3970/cmc.2012.029.169

Abstract In this paper, three-dimensionalT-Trefftz Voronoi Cell Finite Elements (VCFEM-TTs) are developed for micromechanical modeling of heterogeneous materials. Several types of VCFEMs are developed, depending on the types of heterogeneity in each element. Each VCFEM can include alternatively a spherical void, a spherical elastic inclusion, a spherical rigid inclusion, or no voids/inclusions at all.In all of these cases, an inter-element compatible displacement field is assumed at each surface of the polyhedral element, with Barycentric coordinates as nodal shape functions.The T-Trefftz trial displacement fields in each element are expressed in terms of the Papkovich-Neuber solution. Spherical harmonics… More >

K. Choukairy¹, R. Bennacer²

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.2, pp. 155-172, 2012, DOI:10.3970/fdmp.2012.008.155

Abstract This study carries the natural thermosolutal convection induced in heterogeneous porous media. The configuration considered is cartesian. The horizontal and vertical walls are submitted to different mass and heat transfer. The equations which govern this type of flow are solved numerically by using the finite volume method. The flow is considered two-dimensional and laminar. The model of Darcy and the approximation of the Boussinesq are taken into account. The parameters which control the problem are the thermal Darcy-Rayleigh number, Rt, the buoyancy ratio, N, the Lewis number, Le, the aspect ratio of the enclosure, A… More >

De-Shin Liu, Zhen-Wei Zhuang, Cho-Liang Chung

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.2, pp. 39-40, 2011, DOI:10.3970/icces.2011.019.039

Abstract A two-dimensional heterogeneous hybrid moisture element method (HHMEM) for modeling transient moisture diffusion in permeable fiber-reinforced polymer composites is proposed in this paper.
The HHMEM scheme is based on a heterogeneous hybrid moisture element (HHME), whose properties are determined by equivalent moisture capacitance and conductance matrixes calculated using the conventional finite element formulation with the similarity mass/stiffness property and matrix condensing operations. A coupled HHME-FE scheme is developed and implemented in computer codes MATLAB to analyze the transient moisture diffusion characteristics of polymeric composite materials containing multiple permeable fibers. The analysis commences by comparing the… More >

A.P. Selvadurai

The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.3, pp. 67-68, 2011, DOI:10.3970/icces.2011.016.067

Abstract Theme Lecture More >