Search for: representative-volume-element--rve
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    Elastic solids with high concentration of arbitrarily oriented multiphase particles

    , Article Acta Mechanica ; Volume 189, Issue 3-4 , 2007 , Pages 125-139 ; 00015970 (ISSN) Roumi, F ; Shodja, H. M ; Sharif University of Technology
    Springer-Verlag Wien  2007
    The effective properties of elastic solids are strongly linked to their interacting micro-constituent phases. For materials containing dilute distributions of single-phase inhomogeneities, the overall behavior can be estimated in a straightforward manner. But in the non-dilute case, due to the complex inter-particle and particle-matrix interactions the treatment is rather involved. When the particles are heterogeneous, not only become the mentioned interactions more complex, but must properly account for the intra-particle interactions as well. The present work addresses an analytical approach to determine the overall moduli of elastic solids containing random distributions of arbitrarily... 

    Investigation the stability of SWCNT-polymer composites in the presence of CNT geometrical defects using multiscale modeling

    , Article 4th International Conference on Multiscale Materials Modeling, MMM 2008, 27 October 2008 through 31 October 2008 ; 2008 , Pages 163-166 ; 9780615247816 (ISBN) Montazeri, A ; Naghdabadi, R ; Sharif University of Technology
    Department of Scientific Computing, Florida State University  2008
    CNT-reinforced polymer composites have attracted attention due to their exceptional high strength. The high strength can be affected by the presence of defects in the nanotubes used as reinforcements in the practical nanocomposites. In this paper, a Molecular Structural Mechanics / Finite Element (MSM/FE) multiscale modeling is used to study the effect of carbon nanotube geometrical defects on the stability of SWCNT-polymer composites. Here, two types of representative volume elements (RVEs) for these nanocomposites are considered with perfect and defected CNT. These RVEs have the same dimensions. The nanotube is modeled at the atomistic scale using molecular structural mechanics whereas the... 

    Progressive damage analysis of an adhesively bonded composite T-joint under bending, considering micro-scale effects of fiber volume fraction of adherends

    , Article Composite Structures ; Volume 258 , 2021 ; 02638223 (ISSN) Barzegar, M ; Davoodi Moallem, M ; Mokhtari, M ; Sharif University of Technology
    Elsevier Ltd  2021
    In this study, a numerical study on failure assessment and stress distribution on the adhesive region in a composite T-joint under bending load case is investigated using cohesive zone method (CZM). The Finite Element Model (FEM) has been verified with experimental results. To study the load transfer capability of the T-joint, five different adhesives are considered in the adhesive region and the effect of geometrical parameters such as stringer thickness, corner radius, and adherend thickness as well as micromechanical properties of reinforced fiber composite adherends are investigated. Effective properties of two composite adherends including Carbon-Epoxy (IM7/8552) and Glass-Epoxy... 

    Effect of axonal fiber architecture on mechanical heterogeneity of the white matter—a statistical micromechanical model

    , Article Computer Methods in Biomechanics and Biomedical Engineering ; 2021 ; 10255842 (ISSN) Hoursan, H ; Farahmand, F ; Ahmadian, M. T ; Sharif University of Technology
    Taylor and Francis Ltd  2021
    A diffusion tensor imaging (DTI) -based statistical micromechanical model was developed to study the effect of axonal fiber architecture on the inter- and intra-regional mechanical heterogeneity of the white matter. Three characteristic regions within the white matter, i.e., corpus callosum, brain stem, and corona radiata, were studied considering the previous observations of locations of diffuse axonal injury. The embedded element technique was used to create a fiber-reinforced model, where the fiber was characterized by a Holzapfel hyperelastic material model with variable dispersion of axonal orientations. A relationship between the fractional anisotropy and the dispersion parameter of... 

    Compressive modulus and deformation mechanisms of 3DG foams: Experimental investigation and multiscale modeling

    , Article Nanotechnology ; Volume 32, Issue 48 , 2021 ; 09574484 (ISSN) Mahdavi, S. M ; Adibnazari, S ; Del Monte, F ; Gutiérrez, M. C ; Sharif University of Technology
    IOP Publishing Ltd  2021
    Due to the wide applications of three-dimensional graphene (3DG) foam in bio-sensors, stretchable electronics, and conductive polymer composites, predicting its mechanical behavior is of paramount importance. In this paper, a novel multiscale finite element model is proposed to predict the compressive modulus of 3DG foams with various densities. It considers the effects of pore size and structure and the thickness of graphene walls on 3DG foams' overall behavior. According to the scanning electron microscope images, a unit cell is selected in the microscale step to represent the incidental arrangement of graphene sheets in 3DG foams. After derivation of equivalent elastic constants of the... 

    Effects of microstructural morphology on formability, strain localization, and damage of ferrite-pearlite steels: experimental and micromechanical approaches

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 52, Issue 2 , January , 2021 , Pages 711-725 ; 10735623 (ISSN) Isavand, S ; Assempour, A ; Sharif University of Technology
    Springer  2021
    This paper attempts to predict how the microstructural features and mechanical properties of the individual constituents affect the deformation behavior and formability of ferrite-pearlite steels under quasi-static loading at room temperature. For this purpose, finite element simulations using representative volume elements (RVEs) based on the real microstructures were implemented to model the flow behavior of the ferrite-pearlite steels with various microstructural morphologies (non-banded and banded). The homogenized flow curves obtained from the RVEs subjected to periodic boundary conditions together with displacement boundary conditions were validated with the experimental results of the... 

    Fully coupled hydromechanical multiscale model with microdynamic effects

    , Article International Journal for Numerical Methods in Engineering ; Volume 115, Issue 3 , 2018 , Pages 293-327 ; 00295981 (ISSN) Khoei, A. R ; Hajiabadi, M. R ; Sharif University of Technology
    John Wiley and Sons Ltd  2018
    In this paper, a multiscale finite element framework is developed based on the first-order homogenization method for fully coupled saturated porous media using an extension of the Hill-Mandel theory in the presence of microdynamic effects. The multiscale method is employed for the consolidation problem of a 2-dimensional saturated soil medium generated from the periodic arrangement of circular particles embedded in a square matrix, which is compared with the direct numerical simulation method. The effects of various issues, including the boundary conditions, size effects, particle arrangements, and the integral domain constraints for the microscale boundary value problem, are numerically... 

    Micromechanics of brain white matter tissue: a fiber-reinforced hyperelastic model using embedded element technique

    , Article Journal of the Mechanical Behavior of Biomedical Materials ; Volume 80 , April , 2018 , Pages 194-202 ; 17516161 (ISSN) Yousefsani, S. A ; Shamloo, A ; Farahmand, F ; Sharif University of Technology
    Elsevier Ltd  2018
    A transverse-plane hyperelastic micromechanical model of brain white matter tissue was developed using the embedded element technique (EET). The model consisted of a histology-informed probabilistic distribution of axonal fibers embedded within an extracellular matrix, both described using the generalized Ogden hyperelastic material model. A correcting method, based on the strain energy density function, was formulated to resolve the stiffness redundancy problem of the EET in large deformation regime. The model was then used to predict the homogenized tissue behavior and the associated localized responses of the axonal fibers under quasi-static, transverse, large deformations. Results... 

    A hierarchical thermo-mechanical multi-scale technique for modeling of edge dislocations in nano-crystalline structures

    , Article Computational Materials Science ; Volume 141 , 2018 , Pages 360-374 ; 09270256 (ISSN) Jahanshahi, M ; Khoei, A. R ; Heidarzadeh, N ; Jafarian, N ; Sharif University of Technology
    Elsevier B.V  2018
    In this paper, a hierarchical multi-scale technique is developed to investigate the thermo-mechanical behavior of nano-crystalline structures in the presence of edge dislocations. The primary edge dislocations are generated by proper adjustment of atomic positions to resemble discrete dislocations. The interatomic potential used to perform atomistic simulation is based on the Finnis-Sinclair embedded-atom method as many-body potential and, the Nose-Hoover thermostat is employed to control the effect of temperature. The strain energy density function is obtained for various representative volume elements under biaxial and shear loadings by fitting a fourth order polynomial in the atomistic... 

    Effect of interphase zone on the overall elastic properties of nanoparticle-reinforced polymer nanocomposites

    , Article Journal of Composite Materials ; Volume 53, Issue 9 , 2019 , Pages 1261-1274 ; 00219983 (ISSN) Amraei, J ; Jam, J. E ; Arab, B ; Firouz Abadi, R. D ; Sharif University of Technology
    SAGE Publications Ltd  2019
    In the current work, the effect of interphase region on the mechanical properties of polymer nanocomposites reinforced with nanoparticles is studied. For this purpose, a closed-form interphase model as a function of radial distance based on finite-size representative volume element is suggested to estimate the mechanical properties of particle-reinforced nanocomposites. The effective Young’s and shear moduli of thermoplastic polycarbonate-based nanocomposites for a wide range of sizes and volume fractions of silicon carbide nanoparticles are investigated using the proposed interphase model and molecular dynamics simulations. In order to investigate the effect of particle size, several unit... 

    FE 2 investigation of aggregate characteristics effect on fracture properties of concrete

    , Article International Journal of Fracture ; Volume 226, Issue 2 , 2020 , Pages 243-261 Daneshyar, A ; Ghaemian, M ; Sharif University of Technology
    Springer Science and Business Media B.V  2020
    The relation between aggregate characteristics and fracture properties of concrete mixtures is investigated numerically. A homogenization-based multiscale approach is introduced based on objective failure zone averaging for heterogeneous meso-structure, and traction–separation law of fracture process zone (FPZ) instead of phenomenological constitutive model for macro-structure. A rate-dependent anisotropic damage-plastic formulation is employed to reproduce degradation process in the fine-scale from diffuse damage to localized bands, and extended finite element method (X-FEM) is utilized to resemble the localized region as a macro-crack within the coarse-scale. Different aggregate types are... 

    A hierarchical hyperelastic-based approach for multi-scale analysis of defective nano-materials

    , Article Mechanics of Materials ; Volume 140 , January , 2020 Jahanshahi, M ; Ahmadi, H ; Khoei, A. R ; Sharif University of Technology
    Elsevier B.V  2020
    In this paper, a continuum–atomistic multi-scale method is presented in modeling the nonlinear behavior of nano-materials under large deformation. In order to identify an appropriate strain energy function for crystalline nano-structures with different percentages of spherical voids, the hyperelastic method is employed for specimen whose behavior is determined based on the molecular dynamics analyses. In the atomistic level, the EAM many-body potential is employed to model the interactions between the atoms of Al RVEs. The atomistic strain energy density curves and surfaces are generated by applying the uniaxial, biaxial and simple shear deformations to the boundaries of RVEs. The material... 

    A novel procedure for micromechanical characterization of white matter constituents at various strain rates

    , Article Scientia Iranica ; Volume 27, Issue 2 , 2021 , Pages 784-794 ; 10263098 (ISSN) Hoursan, H ; Farahmand, F ; Ahmadian, M. T ; Sharif University of Technology
    Sharif University of Technology  2021
    Optimal hyperplastic coeficients of the micromechanical constituents of the human brain stem were investigated. An evolutionary optimization algorithm was combined with a Finite Element (FE) model of a Representative Volume Element (RVE) to nd the optimal material properties of axon and Extra Cellular Matrix (ECM). The tension and compression test results of a previously published experiment were used for optimizing the material coeficients, and the shear experiment was used for the validation of the resulting constitutive model. The optimization algorithm was used to search for optimal shear moduli and ber sti ness of axon and ECM by tting the average stress in the axonal direction with the... 

    A three-dimensional statistical volume element for histology informed micromechanical modeling of brain white matter

    , Article Annals of Biomedical Engineering ; Volume 48, Issue 4 , 2020 , Pages 1337-1353 Hoursan, H ; Farahmand, F ; Ahmadian, M. T ; Sharif University of Technology
    Springer  2020
    This study presents a novel statistical volume element (SVE) for micromechanical modeling of the white matter structures, with histology-informed randomized distribution of axonal tracts within the extracellular matrix. The model was constructed based on the probability distribution functions obtained from the results of diffusion tensor imaging as well as the histological observations of scanning electron micrograph, at two structures of white matter susceptible to traumatic brain injury, i.e. corpus callosum and corona radiata. A simplistic representative volume element (RVE) with symmetrical arrangement of fully alligned axonal fibers was also created as a reference for comparison. A...