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  • Open Access


    A Modified Multiscale Model for Microcantilever Sensor

    Yan Zhang1, Shengping Shen1

    CMC-Computers, Materials & Continua, Vol.8, No.1, pp. 17-22, 2008, DOI:10.3970/cmc.2008.008.017

    Abstract In this paper, an existed model for adsorption-induced surface stress is modified with physical clarity, based on the equilibrium of force. In the proposed multiscale model, a four-atom system is used, instead of the existed three-atom system which did not consider the force equilibrium. By analyzing the force state of an atom, the thickness of the first layer atoms can be determined. Thus, the proposed model does not need to determine the layer-thickness by experiments or artificially. The results obtained from the proposed model agree very well with the experimental data. This paper is helpful More >

  • Open Access


    Microstructure Optimization in Fuel Cell Electrodes using Materials Design

    Dongsheng Li1,2, Ghazal Saheli1, Moe Khaleel2, Hamid Garmestani1

    CMC-Computers, Materials & Continua, Vol.4, No.1, pp. 31-42, 2006, DOI:10.3970/cmc.2006.004.031

    Abstract A multiscale model based on statistical continuum mechanics is proposed to predict the mechanical and electrical properties of heterogeneous porous media. This model is applied within the framework of microstructure sensitive design (MSD) to guide the design of the microstructure in porous lanthanum strontium manganite (LSM) fuel cell electrode. To satisfy the property requirement and compatibility, porosity and its distribution can be adjusted under the guidance of MSD to achieve optimized microstructure. More >

  • Open Access


    Multiscale Nonlinear Thermo-Mechanical Coupling Analysis of Composite Structures with Quasi-Periodic Properties

    Zihao Yang1, Liang Ma2, Qiang Ma3, Junzhi Cui1,4, Yufeng Nie1, Hao Dong1, Xiaohong An5

    CMC-Computers, Materials & Continua, Vol.53, No.3, pp. 219-248, 2017, DOI:10.32604/cmc.2017.053.235

    Abstract This paper reports a multiscale analysis method to predict the thermo-mechanical coupling performance of composite structures with quasi-periodic properties. In these material structures, the configurations are periodic and the material coefficients are quasi-periodic, i.e., they depend not only on the microscale information but also on the macro location. Also, a mutual interaction between displacement and temperature fields is considered in the problem, which is our particular interest in this study. The multiscale asymptotic expansions of the temperature and displacement fields are constructed and associated error estimation in nearly pointwise sense is presented. Then, a finite More >

  • Open Access


    A Multiscale Progressive Failure Modeling Methodology for Composites That Includes Fiber Strength Stochastics

    Trenton M. Ricks1, Thomas E. Lacy, Jr.1,2, Brett A. Bednarcyk3, Steven M.Arnold3, John W. Hutchins1

    CMC-Computers, Materials & Continua, Vol.40, No.2, pp. 99-130, 2014, DOI:10.3970/cmc.2014.040.099

    Abstract A multiscale modeling methodology was developed for continuous fiber composites that incorporates a statistical distribution of fiber strengths into coupled multiscale micromechanics/ finite element (FE) analyses. A modified twoparameter Weibull cumulative distribution function, which accounts for the effect of fiber length on the probability of failure, was used to characterize the statistical distribution of fiber strengths. A parametric study using the NASA Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) was performed to assess the effect of variable fiber strengths on local composite failure within a repeating unit cell (RUC) and subsequent global… More >

  • Open Access


    Multiscale Fatigue Life Prediction for Composite Panels

    Brett A. Bednarcyk1, Phillip W. Yarrington2, Steven M. Arnold3

    CMC-Computers, Materials & Continua, Vol.35, No.3, pp. 229-254, 2013, DOI:10.3970/cmc.2013.035.229

    Abstract Fatigue life prediction capabilities have been incorporated into the HyperSizer Composite Analysis and Structural Sizing Software. The fatigue damage model is introduced at the fiber/matrix constituent scale through HyperSizer’s coupling with NASA’s MAC/GMC micromechanics software. This enables prediction of the micro scale damage progression throughout stiffened and sandwich panels as a function of cycles leading ultimately to simulated panel failure. The fatigue model implementation uses a cycle jumping technique such that, rather than applying a specified number of additional cycles, a specified local damage increment is specified and the number of additional cycles to reach More >

  • Open Access


    On Multiscale Modeling Using the Generalized Method of Cells: Preserving Energy Dissipation across Disparate Length Scales

    E. J. Pineda1, B. A. Bednarcyk1, A. M. Waas2, S. M. Arnold1

    CMC-Computers, Materials & Continua, Vol.35, No.2, pp. 119-154, 2013, DOI:10.3970/cmc.2013.035.119

    Abstract A mesh objective crack band model was implemented within the generalized method of cells micromechanics theory. This model was linked to a macroscale finite element model to predict post-peak strain softening in composite materials. Although a mesh objective theory was implemented at the microscale, it does not preclude pathological mesh dependence at the macroscale. To ensure mesh objectivity at both scales, the energy density and the energy release rate must be preserved identically across the two scales. This requires a consistent characteristic length or localization limiter. The effects of scaling (or not scaling) the dimensions More >

  • Open Access


    Influence of Scale Specific Features on the Progressive Damage of Woven Ceramic Matrix Composites (CMCs)

    K. C. Liu1, S. M. Arnold2

    CMC-Computers, Materials & Continua, Vol.35, No.1, pp. 35-65, 2013, DOI:10.3970/cmc.2013.035.035

    Abstract It is well known that failure of a material is a locally driven event. In the case of ceramic matrix composites (CMCs), significant variations in the microstructure of the composite exist and their significance on both deformation and life response need to be assessed. Examples of these variations include changes in the fiber tow shape, tow shifting/nesting and voids within and between tows. In the present work, the influence of many of these scale specific architectural features of woven ceramic composite are examined stochastically at both the macroscale (woven repeating unit cell (RUC)) and structural More >

  • Open Access


    Multiscale Modeling of Crystalline Energetic Materials.

    O. U. Ojeda1 and T. Çagınˇ 1

    CMC-Computers, Materials & Continua, Vol.16, No.2, pp. 127-174, 2010, DOI:10.3970/cmc.2010.016.127

    Abstract The large discrepancy in length and time scales at which characteristic processes of energetic materials are of relevance pose a major challenge for current simulation techniques. We present a systematic study of crystalline energetic materials of different sensitivity and analyze their properties at different theoretical levels. Information like equilibrium structures, vibrational frequencies, conformational rearrangement and mechanical properties like stiffness and elastic properties can be calculated within the density functional theory (DFT) using different levels of approximations. Dynamical properties are obtained by computations using molecular dynamics at finite temperatures through the use of classical force fields. More >

  • Open Access


    Multiscale Nonlinear Constitutive Modeling of Carbon Nanostructures Based on Interatomic Potentials

    J. Ghanbari1, R. Naghdabadi1,2

    CMC-Computers, Materials & Continua, Vol.10, No.1, pp. 41-64, 2009, DOI:10.3970/cmc.2009.010.041

    Abstract Continuum-based modeling of nanostructures is an efficient and suitable method to study the behavior of these structures when the deformation can be considered homogeneous. This paper is concerned about multiscale nonlinear tensorial constitutive modeling of carbon nanostructures based on the interatomic potentials. The proposed constitutive model is a tensorial equation relating the second Piola-Kirchhoff stress tensor to Green-Lagrange strain tensor. For carbon nanotubes, some modifications are made on the planar representative volume element (RVE) to account for the curved atomic structure resulting a non-planar RVE. Using the proposed constitutive model, the elastic behavior of the More >

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