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  • Open Access


    Effective Elastic Properties of 3-Phase Particle Reinforced Composites with Randomly Dispersed Elastic Spherical Particles of Different Sizes

    Yu-Fu Ko1,* , Jiann-Wen Woody Ju2

    CMES-Computer Modeling in Engineering & Sciences, Vol.129, No.3, pp. 1305-1328, 2021, DOI:10.32604/cmes.2021.017589

    Abstract Higher-order multiscale structures are proposed to predict the effective elastic properties of 3-phase particle reinforced composites by considering the probabilistic spherical particles spatial distribution, the particle interactions, and utilizing homogenization with ensemble volume average approach. The matrix material, spherical particles with radius a1, and spherical particles with radius a2, are denoted as the 0th phase, the 1st phase, and the 2nd phase, respectively. Particularly, the two inhomogeneity phases are different particle sizes and the same elastic material properties. Improved higher-order (in ratio of spherical particle sizes to the distance between the centers of spherical particles) bounds on effective elastic properties… More >

  • Open Access


    Coupling VEM and BEM for computational homogenization of composite materials

    Marco Lo Cascio1, Marco Grifò1, Alberto Milazzo1, Ivano Benedetti1,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.23, No.1, pp. 13-13, 2021, DOI:10.32604/icces.2021.08335

    Abstract The Virtual Element Method (VEM) [1] is a recent numerical technique that is capable of dealing with very general polygonal and polyhedral mesh elements, including irregular or non-convex ones. Because of this feature, the VEM ensures noticeable simplification in the data preparation stage of the analysis, especially for problems whose analysis domain features complex geometries, as in the case of computational micromechanics problems [2]. The Boundary Element Method (BEM) [3] is a well-known, extensively used and efficient numerical technique that has been successfully employed for the computational homogenization of materials with complex morphologies [4]. Due to its underlying formulation, the… More >

  • Open Access


    Cohesive Strength and Separation Energy as Characteristic Parameters of Fracture Toughness and Their Relation to Micromechanics

    W. Brocks1

    Structural Durability & Health Monitoring, Vol.1, No.4, pp. 233-244, 2005, DOI:10.3970/sdhm.2005.001.233

    Abstract A review on phenomenological fracture criteria is given, based on the energy balance for cracked bodies, and the respective toughness parameters are related to micromechanical processes. Griffith's idea of introducing a "surface energy" and Barenblatt's concept of a "process zone" ahead of the crack tip build the foundation of modern cohesive models, which have become versatile tools for numerical simulations of crack extension. The cohesive strength and the separation energy used as phenomenological material parameters in these models appear to represent a physically significant characterisation of "fracture toughness". Micromechanical interpretations of these parameters can be derived, depending on the specific… More >

  • Open Access


    Discrete Modelling of Capillary Mechanisms in Multi-Phase Granular Media

    L. Scholtès1, B. Chareyre2, F.Nicot3, F. Darve4

    CMES-Computer Modeling in Engineering & Sciences, Vol.52, No.3, pp. 297-318, 2009, DOI:10.3970/cmes.2009.052.297

    Abstract A numerical study of multi-phase granular materials based upon micro-mechanical modelling is proposed. Discrete element simulations are used to investigate capillary induced effects on the friction properties of a granular assembly in the pendular regime. Capillary forces are described at the local scale through the Young-Laplace equation and are superimposed to the standard dry particle interaction usually well simulated through an elastic-plastic relationship. Both effects of the pressure difference between liquid and gas phases and of the surface tension at the interface are integrated into the interaction model. Hydraulic hysteresis is accounted for based on the possible mechanism of formation… More >

  • Open Access


    Multi-Inclusion Unit Cell Studies of Reinforcement Stresses and Particle Failure in Discontinuously Reinforced Ductile Matrix Composites

    H.J. Bohm¨ 1, W. Han1,2, A. Eckschlager1,3

    CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 5-20, 2004, DOI:10.3970/cmes.2004.005.005

    Abstract Three-dimensional periodic micromechanical models are used for studying the mechanical behavior of discontinuously reinforced ductile matrix composites. The models are based on unit cells that contain a number of randomly positioned and, where applicable, randomly oriented spherical, spheroidal or cylindrical reinforcements. The Finite Element method is used to resolve the microscale stress and strain fields and to predict the homogenized responses under overall uniaxial tensile loading in the elastic and elastoplastic regimes. Periodicity boundary conditions are employed in the analyses.\\ The main emphasis of the contribution is put on studying the microscale stresses in the reinforcements, which are evaluated in… More >

  • Open Access


    Computational Modeling of Dual-Phase Ceramics with Finsler-Geometric Phase Field Mechanics

    John D. Clayton1,*

    CMES-Computer Modeling in Engineering & Sciences, Vol.120, No.2, pp. 333-350, 2019, DOI:10.32604/cmes.2019.06342

    Abstract A theory invoking concepts from differential geometry of generalized Finsler space in conjunction with diffuse interface modeling is described and implemented in finite element (FE) simulations of dual-phase polycrystalline ceramic microstructures. Order parameters accounting for fracture and other structural transformations, notably partial dislocation slip, twinning, or phase changes, are dimensionless entries of an internal state vector of generalized pseudo-Finsler space. Ceramics investigated in computations are a boron carbide-titanium diboride (B4C-TiB2) composite and a diamond-silicon carbide (C-SiC) composite. Deformation mechanisms-in addition to elasticity and cleavage fracture in grains of any phase-include restricted dislocation glide (TiB2 phase), deformation twinning (B4C and β-SiC… More >

  • Open Access


    Micromechanics-Based Elastic Fields of Closed-Cell Porous Media

    Lianhua Ma1, Qingsheng Yang2, *

    CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.2, pp. 239-259, 2018, DOI:10.3970/cmes.2018.114.239

    Abstract Fluid-filled closed-cell porous media could exhibit distinctive features which are influenced by initial fluid pressures inside the cavities. Based on the equivalent far-field method, micromechanics-based solutions for the local elastic fields of porous media saturated with pressurized fluid are formulated in this paper. In the present micromechanics model, three configurations are introduced to characterize the different state the closed-cell porous media. The fluid-filled cavity is assumed to be a compressible elastic solid with a zero shear modulus, and the pressures in closed pores are represented by eigenstrains introduced in fluid domains. With the assumption of spheroidal fluid-filled pores, the local… More >

  • Open Access


    Elasto-Plastic MLPG Method for Micromechanical Modeling of Heterogeneous Materials

    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 the unidirectional composite material. A… More >

  • Open Access


    A Micromechanical Model for Estimating the Effective Stiffness of a Pair of Micro-cracked Interfaces in an Orthotropic Trimaterial under Inplane Deformations

    X. Wang1, W.T. Ang1,2, H. Fan1

    CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.2, pp. 81-101, 2015, DOI:10.3970/cmes.2015.107.081

    Abstract A micromechanical model is proposed here for estimating the effective stiffness of a pair of parallel microscopically damaged interfaces in a trimaterial under inplane elastostatic deformations. The trimaterial is made of an orthotropic thin layer sandwiched between two orthotropic half-spaces. The microscopically damaged interfaces are modeled using periodically distributed interfacial micro-cracks. The micromechanical model is formulated and numerically solved in terms of hypersingular boundary integro-differential equations. The effects of the width of the thin layer, the micro-crack densities of the two interfaces and the material constants of the thin layer and the two half-spaces on the effective stiffness coefficients are… More >

  • Open Access


    Effect of CNT Agglomeration on the Electrical Conductivity and Percolation Threshold of Nanocomposites: A Micromechanics-based Approach

    B.J. Yang1, K.J. Cho1, G.M. Kim1, H.K. Lee1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.103, No.5, pp. 343-365, 2014, DOI:10.3970/cmes.2014.103.343

    Abstract The addition of carbon nanotubes (CNTs) to a matrix material is expected to lead to an increase in the effective electrical properties of nanocomposites. However, a CNT entanglement caused by the matrix viscosity and the high aspect ratio of the nanotubes often inhibits the formation of a conductive network. In the present study, the micromechanics-based model is utilized to investigate the effect of CNT agglomeration on the electrical conductivity and percolation threshold of nanocomposites. A series of parametric studies considering various shapes and curviness distributions of CNTs are carried out to examine the effects of entanglement on the electrical performance… More >

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